How to wire up a 240VAC receptacle

[Spork Schivago]

Hello,

I have a device that has an IEC 60309 3-prong 32 amp plug.   It expects a 3-prong receptacle that has neutral, ground, and line.   Because I live in the US, how could I safely wire up the correct receptacle that has neutral, ground, and line, while still providing 240VAC and not violating the NEC?

I have single phase 120-0-120 coming into the house to the panel.

Thanks.

[GerryBags]

You need a transformer. We use 120V on work sites in the UK, so there are plenty of 240V-120V "site" transformers knocking around. You could use one of those backwards, but not to the rated current draw as the secondary's likely to be lighter guage.

You really want something more like this: https://www.mtixtl.com/actoactransformer800wmaxdualchange220240v-110120vtf-220110-800-2.aspx

[Spork Schivago]

You need a transformer. We use 120V on work sites in the UK, so there are plenty of 240V-120V "site" transformers knocking around. You could use one of those backwards, but not to the rated current draw as the secondary's likely to be lighter guage.

You really want something more like this: https://www.mtixtl.com/actoactransformer800wmaxdualchange220240v-110120vtf-220110-800-2.aspx

Yes, I'd need some sort of step-up transformer.   That's where I'm getting stuck.   I need to go from 120VAC to 240VAC, but with the proper plug.   My device draws up to 7.3KVA but has a maximum rating of 10KVA in the tech documents.   I'm having trouble with figuring out what exact step-up transformer I'd need, what size breaker in the panel, etc.

I can send a pic of the actual plug, if it'd help.   It's blue and has three plugs.   I'd rather be able to plug this directly into the step-up transformer, rather than use some sort of adapter.

I am wondering if there's any way to tear the rack mount PDU apart and rewire it to accept the 120VAC L1, 120VAC L2, and neutral / ground?   Probably not, right?   Essentially, it's not as simple as just switching out the power cord, is it?   The only way is with a step-up transformer?

[Spork Schivago]

I'm looking at similar plugs on internationalconfig.com and see stuff that says 2P+E.   I read that means 2 pole plus earth, but does that mean 2 hots and one Earth?   If so, I wonder if my three prong plug expects two 120VACs and one Earth, instead of one 240VAC, earth, and ground?  The document on the PDU doesn't say much.   The model of the PDU is HPE P9S16A.

It was listed as Single-Phase international.   It was the only one that fit the requirements we had.   We couldn't get three phase ran here because of the price.  My plug has the 2P + Earth symbol written on it.

[Spork Schivago]

No, you don't need a transformer.  You just wire the device hot and neutral to the incoming split phase lines.
This is how every 240V device works in the US.

But what if the device isn't a US device?   Do you see what I'm saying?   I see the IEC 90603 IP44 32-Amps are a European connector.   In the US, we have 15 amp, 20-amp, 30-amp, etc breakers.   We generally don't have 16-amp or 32-amp breakers.   In Europe, they don't have two 120VAC lines like we do, I don't think, and this is the problem.   I believe the plug expects a ground, a neutral, and a 240VAC hot, not two 120VAC hots

[IanB]

I have a device that has an IEC 60309 3-prong 32 amp plug.   It expects a 3-prong receptacle that has neutral, ground, and line.   Because I live in the US, how could I safely wire up the correct receptacle that has neutral, ground, and line, while still providing 240VAC and not violating the NEC?

Either you can find the appropriate 240 V NEC socket that is rated for the current your device consumes and wire that up to your panel using the appropriate conductor thickness and current rating for the circuit breaker. Then you can construct a fly-lead with an NEC plug on one end and the correct IEC 60309 receptacle on the other. Or you can install the appropriate IEC 60309 receptacle directly in the wall at the end of your 240 V circuit.

Note that "normal" outlets are typically rated for 15-20 A maximum, so if your device consumes more than 18 A or so you will need a special dedicated circuit with the right current rating. Consult an electrician if you have any doubts.

[IanB]

But what if the device isn't a US device?   Do you see what I'm saying?   I see the IEC 90603 IP44 32-Amps are a European connector.   In the US, we have 15 amp, 20-amp, 30-amp, etc breakers.   We generally don't have 16-amp or 32-amp breakers.   In Europe, they don't have two 120VAC lines like we do, I don't think, and this is the problem.   I believe the plug expects a ground, a neutral, and a 240VAC hot, not two 120VAC hots

Although some parts of Europe have a line-neutral-ground arrangement, other parts of Europe may have a line-line-ground arrangement. So it's highly unlikely to make a difference to your device if you feed it the North American version of 240 V with two lines and no neutral.

[helius]

I believe the plug expects a ground, a neutral, and a 240VAC hot, not two 120VAC hots

As long as the device is properly designed and constructed, it makes no difference.

[Gregg]

A lot depends on how the device that you are powering is configured.  If you can find the manufacturer’s installation documents, it is a possibility that you can wire it to your 240V household panel with its own 30 amp two pole breaker.  If it is something like an inverter welder, this is a pretty good possibility. 
The IEC 60309 plugs are labeled L, N, and G for reference as they are used in many other countries where the neutral is closely referenced to ground and the labels are to keep connections standard.  Just make sure you get the ground correct if your equipment can use 120/240 volt power directly.  There is nothing wrong with IEC 60309 plugs and receptacles; but they are not cheap.  A set of L6-30 twist locks may be cheaper than buying the IEC 60309 receptacle.

[Spork Schivago]

So, just to be clear, so long as I purchase a 2P+E 32-amp receptacle, I can just wire the hots from a double pole 20-amp breaker, and run one of the hots to the neutral?    Or do I run one of the hots to the ground?    The receptacles I've been looking at for this have ground, neutral, line, where line is 240VAC.

Instead of hooking neutral to neutral, I'd hook neutral to 120VAC, then line to 120VAC, and ground to ground?   Using 12/2?

The device draws a good bit of current, but nothing insane.   7300KVA, or around 30 amp when running optimally (80% load).

[Spork Schivago]

A lot depends on how the device that you are powering is configured.  If you can find the manufacturer’s installation documents, it is a possibility that you can wire it to your 240V household panel with its own 30 amp two pole breaker.  If it is something like an inverter welder, this is a pretty good possibility. 
The IEC 60309 plugs are labeled L, N, and G for reference as they are used in many other countries where the neutral is closely referenced to ground and the labels are to keep connections standard.  Just make sure you get the ground correct if your equipment can use 120/240 volt power directly.  There is nothing wrong with IEC 60309 plugs and receptacles; but they are not cheap.  A set of L6-30 twist locks may be cheaper than buying the IEC 60309 receptacle.

I'd void warranty if I replaced the plug.   I'm going to purchase the receptacle from Europe.   Buddy of mine over there has them dirt cheap.

The pics I uploaded have the L1 and Earth symbol (G), but doesn't list N.   This equipment cannot run off 120VAC by itself.   It's not one of those 120V or 240V.   It requires 200VAC - 240VAC to operate.   It's just a Power Distribution Unit for a server rack.   A horizontal, metered one, made by Hewlett Packard Enterprise (or at least they outsourced someone to make it for them).

For my cheap BGA rework station, I used the NEMA L6-30 twist locks.   They're okay, feel kinda cheap, but eh.   It works and passed inspection.   I want to make sure this passes inspection before I fill out the paperwork for the permit and purchase the receptacle over in Europe, purchase the wire, run it, and also make sure it's definitely not gonna fry the PDU.

[IanB]

So, just to be clear, so long as I purchase a 2P+E 32-amp receptacle, I can just wire the hots from a double pole 20-amp breaker, and run one of the hots to the neutral?    Or do I run one of the hots to the ground?    The receptacles I've been looking at for this have ground, neutral, line, where line is 240VAC.

It will make a nice bang if you connect a hot wire to ground 

Instead of hooking neutral to neutral, I'd hook neutral to 120VAC, then line to 120VAC, and ground to ground?   Using 12/2?

The device draws a good bit of current, but nothing insane.   7300KVA, or around 30 amp when running optimally (80% load).

The best way to think about things is to forget that "neutral" wires exist. Just consider all power conductors to be hot, and keep them well away from ground.

Note that a 20 amp circuit is no good for a device that will draw 30 amps or more. You will probably want a 35 or 40 amp circuit for that (with appropriate wire thickness and breaker).

[Spork Schivago]

So, just to be clear, so long as I purchase a 2P+E 32-amp receptacle, I can just wire the hots from a double pole 20-amp breaker, and run one of the hots to the neutral?    Or do I run one of the hots to the ground?    The receptacles I've been looking at for this have ground, neutral, line, where line is 240VAC.

It will make a nice bang if you connect a hot wire to ground 

Instead of hooking neutral to neutral, I'd hook neutral to 120VAC, then line to 120VAC, and ground to ground?   Using 12/2?

The device draws a good bit of current, but nothing insane.   7300KVA, or around 30 amp when running optimally (80% load).

The best way to think about things is to forget that "neutral" wires exist. Just consider all power conductors to be hot, and keep them well away from ground.

Note that a 20 amp circuit is no good for a device that will draw 30 amps or more. You will probably want a 35 or 40 amp circuit for that (with appropriate wire thickness and breaker).

What I did, before I read your post, was take my DMM and read the continuity between the pin with the Earth symbol and the external earth symbol green screw and seen 0 ohm resistance and came to the same conclusion you did about the crispiness.

I measured between L/+ and the unlabeled one and got 0.391Mohm (mega ohm).   Then I measured between the unlabeled pin and Earth and got infinite.

I believe I will be good with a double pole 20-amp breaker, where each breaker is providing 120VAC at 20-amp.   Correct me if I'm wrong here, but two 20-amp breakers each providing 120VAC would be equal to one 240VAC breaker allowing up to 40-amp current draw, correct?   If I were using one breaker, then yes, I'd need a 35 or 40 amp breaker, but because I'm going to use a double-pole 20-amp breaker and run one of the hots to the L/+, and the other hot to the unlabeled pin, the neutral to the Earth symbol, I should be good to go, right?

What type of wire would I buy that wouldn't have the bare copper ground but three coated individual wires inside?   Would it be 12/2 without ground?   NM-B should be fine for basement installation, right?

[IanB]

I believe I will be good with a double pole 20-amp breaker, where each breaker is providing 120VAC at 20-amp.   Correct me if I'm wrong here, but two 20-amp breakers each providing 120VAC would be equal to one 240VAC breaker allowing up to 40-amp current draw, correct?

Not correct. 20 amps is 20 amps. If your load is 40 amps you need a breaker and circuit rated at more than 40 amps (using the appropriate safety margin according to the relevant section of code).

What type of wire would I buy that wouldn't have the bare copper ground but three coated individual wires inside?   Would it be 12/2 without ground?   NM-B should be fine for basement installation, right?

It's probably best you employ a commercial electrician. Once you start asking these sorts of questions it suggests you are out of your depth.

[radar_macgyver]

What type of wire would I buy that wouldn't have the bare copper ground but three coated individual wires inside?   Would it be 12/2 without ground?   NM-B should be fine for basement installation, right?

If it's to go from the wall plug to device, you shouldn't use NM, that's for in-wall use only. You can get either SOOW cable or type-W cable for this purpose. For in-wall use, if you want a cable type that has an insulated ground, consider type MC cable. Both SOOW and MC are available at home improvement stores. Type-W is usually only sold at electrical supply stores, or  you can buy online. My preferred vendor is https://www.wireandcableyourway.com/

Buy a pocket NEC guide for information on selecting wire gauge etc. Or, as IanB says, get a pro to install an outlet.

[Richard Crowley]

If your mystery device draws 30A, and given your apparent lack of expertise with mains wiring, then you should NOT be trying to rig up something DIY.  You need a proper, high-current branch circuit with the proper gauge wiring from the distribution point ("breaker panel") and a suitably-rated circuit breaker.  No amount of fooling around with typical 15 or 20 amp branch circuits is going to deliver what you need. The connector is the least of your issues.

[Spork Schivago]

Guys, listen, I tried the professional electricians.   They're all good until they see the pic of the plug, and then they say they can't do it.

That's why I'm here, to make sure I don't hurt myself.   If I could pay someone, I would.   But now I think is a good time for me to learn some stuff.    I thought each line would be able to provide up to a 20-amp draw, as in 20-amp draw from one hot, 20-amp draw from another, with the double-pole breakers.   You guys are saying that's not the case though?   Because the pins are separated from each other by the 0.391 mega ohm resistance or whatever it was, I am looking at those two lines not really as one.   I gave the model of the device in the first post.   It's an HPE P9S16A PDU.

I'm looking at how the receptacle is supposed to be wired up, and we're going against that, obviously.   The receptacle is supposed to have one neutral, one ground, one 240VAC hot.    The professional electrician who came in and installed the 200-amp panel had his work inspected, and it passed, and he used NM-B.   I thought that was wrong, after reading what NM-B was for, that's the reason I asked.   If I don't know something or if I doubt something, I'll ask, instead of just doing it.

I have no problems using a 40 amp double pole breaker, but I think the most important part is for me to understand why I need a 40-amp double pole breaker, so I learn.   Isn't it that each breaker can provide up to whatever they're rated?   So a 40-amp double pole breaker, each breaker can handle up to 40-amps of current?   I understand they're not meant to draw 40-amp continuously.

I wanted to go with what I've always called MX wire, but I think it's really called MC.   It's shielded with the metal around it.   But then I figured I'd run the NM-B and run it through conduit, like the electrician did.   I am glad to know that is not allowed.   Don't know how or why the inspector passed him on that.

[IanB]

You haven't been told you can't use NM-B to wire a fixed circuit from the breaker panel to a wall outlet. You can. That's why an electrician is able to do so and have the work pass inspection.

You keep getting hung up on "hot" and "neutral". But a circuit has two wires. You can think of them as "out" and "back". Whatever current flows "out" has to flow "back". 20 amps out, 20 amps back. The current in the two conductors is always equal and balanced. That's why you can't add up 20 and 20 to get 40.

You can work out for yourself why two 120 V, 20 A circuits do not add up to a 240 V, 40 A circuit. Think about it. 120 V x 20 A = 2400 W. Therefore 2 x 120 V x 20 A = 4800 W. But 240 V x 40 A = 9600 W. And 4800 W does not equal 9600 W. It doesn't add up.

If your load draws 30 amps then the "out" wire has to carry 30 amps and the "back" wire has to carry 30 amps, and each pole of the breaker has to carry 30 amps.

[Paul Moir]

The reason why the professional electricians can't accommodate the plug is that they're not allowed to wire in the European socket.  They must use sockets that are allowed for permanent installations in North America, which are pretty much NEMA sockets.  So have them wire in a dryer socket (30A) or a range socket (40A), then construct an adapter made with a dryer or range plug to your European socket. 
If you go out early on garbage day with a set of wire cutters, you can get the plug extra cheap. 

[Zero999]

Ian is right. It will make no difference. Here in the UK it's done the other way round: 110V equipment is routinely powered off 55V-0-55V split phase (55V with respect to neutral) or two phases of a 110V three phase supply (63.5V with respect to neutral). It's perfectly safe: it works without killing or shocking anyone!

[Spork Schivago]

You haven't been told you can't use NM-B to wire a fixed circuit from the breaker panel to a wall outlet. You can. That's why an electrician is able to do so and have the work pass inspection.

You keep getting hung up on "hot" and "neutral". But a circuit has two wires. You can think of them as "out" and "back". Whatever current flows "out" has to flow "back". 20 amps out, 20 amps back. The current in the two conductors is always equal and balanced. That's why you can't add up 20 and 20 to get 40.

You can work out for yourself why two 120 V, 20 A circuits do not add up to a 240 V, 40 A circuit. Think about it. 120 V x 20 A = 2400 W. Therefore 2 x 120 V x 20 A = 4800 W. But 240 V x 40 A = 9600 W. And 4800 W does not equal 9600 W. It doesn't add up.

If your load draws 30 amps then the "out" wire has to carry 30 amps and the "back" wire has to carry 30 amps, and each pole of the breaker has to carry 30 amps.

Thank you for explaining that.   I want to apologize for my response last night.   There's something really wrong with me and on Friday, the doctor said it was time to go to the ER.   But I was waiting until Mothers Day was over with.   I haven't gotten much sleep.   I'm real worried now.   I weighed around 207 lbs maybe 6 months ago and now I'm down in the 150 lbs, but nothing has changed.   I just keep dropping it.   At first, I was happy, but now, it's got us all concerned.   I'm going to be going to the ER later today and might not be back for a bit.

I purchased a 40-amp double pole breaker.

So, is there any danger with going for a larger breaker than what is actually needed?   I know I can run 14 gauge wire on a 20-amp breaker.   I know I can't run 12 gauge wire on a 15-amp breaker.   With this PDU and it's dedicated circuit, hypothetically, if I went for a 100-amp breaker, would that be dangerous?   Essentially, would it only trip after it draws more than 100-amp or would it trip as soon as it noticed some sort of short or something?    I'm not talking about GFCI breakers or arc-fault breakers.   Just the normal D-Square Home-Line ones.

For the NM-B, I thought radar_macgyver said it's for in-wall use only.   My receptacle is rated for the 32-amp, the proper mate to this plug.   When it says 32-amp, being a European plug, I believe that's 40-amp derated to 80%.   I believe that's how they categorize their breakers, at the derated current.

I'll be using 8-gauge wire, but I need clarification on the NM-B.   I see NM-B (non-metallic sheathed cable) may be used for both exposed and concealed work in normally dry locations at temperatures not to exceed 90°C (with ampacity limited to that for 60°C conductors) as specified in the National Electrical Code.  NM-B cable is primarily used in residential wiring as branch circuits for outlets, switches, and other loads.  NM-B cable may be run in air voids of masonry block or tile walls where such walls are not subject to excessive moisture or dampness.  Voltage rating for NM-B cable is 600 volts.

For the receptacle, they show no bare copper wires being hooked up, so I was thinking of going for something like 8/3 without ground, but then using the neutral for ground.   Would that be best or would it be better to go for 8/2 with ground, and just hook the copper ground to the ground pin?   I'm bonding the PDU to the rack, and the rack to the bonding cable that bonds the ethernet, coax, gas-lines, waterlines, etc together.   I know I have to mark any non-black wires with red tape or something to show the next person it's hot.

The reason I feel I need to understand this is because some kid (from the previous owners) did some electrical work and didn't do it right at all.   I feel the need to be able to identify what's wrong in this house, electrical wise, and fix it.   We have a daughter and I don't want the house burning down.   A good example is the ground wire running to the gang boxes but not actually being hooked to the receptacles, not even the GFCI receptacles.   That's just not safe at all.   I went through and wired a pig tail to the switches and receptacles to fix that.

[Richard Crowley]

I'm going to be going to the ER later today and might not be back for a bit.

Our best wishes that they can diagnose the problem and solve it.

So, is there any danger with going for a larger breaker than what is actually needed? 

The answer that made sense to me was:  You must NOT over-rate the breaker for the wire gauge of the circuit. (Or conversely, you must not UNDER-rate the cable for the breaker current.  The reason given was that you want the BREAKER to "blow" under a fault condition, and NOT the wiring.  Because the breaker (or fuses)  are designed to safely trip/blow in a controlled environment.  But the wiring is running through your walls (or attic or basement, etc.)  And especially in domestic installations, it is not running through metal conduit tubing.  So overheating of the branch circuit wiring could actually set you house on fire if the breaker doesn't trip properly.

[Yansi]

So, just to be clear, so long as I purchase a 2P+E 32-amp receptacle, I can just wire the hots from a double pole 20-amp breaker, and run one of the hots to the neutral?    Or do I run one of the hots to the ground?    The receptacles I've been looking at for this have ground, neutral, line, where line is 240VAC.

It will make a nice bang if you connect a hot wire to ground 

Instead of hooking neutral to neutral, I'd hook neutral to 120VAC, then line to 120VAC, and ground to ground?   Using 12/2?

The device draws a good bit of current, but nothing insane.   7300KVA, or around 30 amp when running optimally (80% load).

The best way to think about things is to forget that "neutral" wires exist. Just consider all power conductors to be hot, and keep them well away from ground.

Note that a 20 amp circuit is no good for a device that will draw 30 amps or more. You will probably want a 35 or 40 amp circuit for that (with appropriate wire thickness and breaker).

In fact, neutral wire should always be treated as hot and never touched.

[IanB]

Sorry to hear about your health problems. I hope you get good answers from the doctors.

I know I can run 14 gauge wire on a 20-amp breaker.

I'm not so sure about that.

I know I can't run 12 gauge wire on a 15-amp breaker.

Why ever not?

The breaker is there to protect the wiring. If the wire carries too much current it can overheat and potentially cause a fire. The job of the breaker is to trip before that happens.

It really seems you should hire an electrician to do the work for you. As someone suggested above, have the electrician install a suitable NEMA socket in the wall (like a range outlet), and then have the electrician wire up an adapter cable with NEMA plug and IEC socket to go to your device.

[Spork Schivago]

The reason why the professional electricians can't accommodate the plug is that they're not allowed to wire in the European socket.  They must use sockets that are allowed for permanent installations in North America, which are pretty much NEMA sockets.  So have them wire in a dryer socket (30A) or a range socket (40A), then construct an adapter made with a dryer or range plug to your European socket. 
If you go out early on garbage day with a set of wire cutters, you can get the plug extra cheap. 

They can't do it because it's against the NEC?   As in I cannot legally do it either because it's against code?

This might explain the drastic price difference between the sockets over in Europe and the same sockets that say they're rated for North America.   The European ones are around 4 to 7 of their funky dollars (the L / F pound thing).   But the North American ones that I've seen are usually 100$ USD +.

[dmills]

One other gotcha....

Look at that PDU, does it fuse or breaker both legs of the outgoing circuit? My bet is that it does not (Being as EU generally has the "neutral" bonded to ground).

Now think about what happens if you run it off a split phase supply and some outgoing cable has a neutral/earth fault!

Regards, Dan.

[IanB]

This might explain the drastic price difference between the sockets over in Europe and the same sockets that say they're rated for North America.   The European ones are around 4 to 7 of their funky dollars (the L / F pound thing).   But the North American ones that I've seen are usually 100$ USD +.

I suspect the reason for the price difference in the USA is that they are a low volume, special import item, primarily with industrial applications. For these reasons I suspect they can charge a price premium. I doubt the actual quality is any different compared to a branded item in Europe.

[james_s]

IMHO you would be well served by a good book on electrical wiring, I have a copy of this https://www.amazon.com/Wiring-House-5th-Pros/dp/162710674X and have found it to be well written and has a lot of helpful tips and tricks.

The breaker is there to protect the wire, so it's perfectly ok to use wire larger than required, for example 12AWG on a 15A breaker but you CANNOT go the other way, eg 14AWG on a 20A breaker. It's also perfectly ok to use a larger capacity circuit than required by the load, so a 40A circuit is just fine for a load only requiring 20A so long as the wire is adequately sized for the breaker, 8AWG for 40A.

[tpowell1830]

The reason why the professional electricians can't accommodate the plug is that they're not allowed to wire in the European socket.  They must use sockets that are allowed for permanent installations in North America, which are pretty much NEMA sockets.  So have them wire in a dryer socket (30A) or a range socket (40A), then construct an adapter made with a dryer or range plug to your European socket. 
If you go out early on garbage day with a set of wire cutters, you can get the plug extra cheap. 

They can't do it because it's against the NEC?   As in I cannot legally do it either because it's against code?

This might explain the drastic price difference between the sockets over in Europe and the same sockets that say they're rated for North America.   The European ones are around 4 to 7 of their funky dollars (the L / F pound thing).   But the North American ones that I've seen are usually 100$ USD +.

Depends on your local laws, rules and regulations about legality... In my area, I am allowed to make changes in my house to electrical circuits, but, if a fire developed from a mistake in my wiring, AND the insurance company found out, the house is not covered under the rules of insurance, so therefore, I just ate it...

Since you are not knowledgeable about wiring, pay the $100 for the outlet, wire it up to local codes/standards/components, pay the electrician and save yourself all that headache.

Just my 2 cents...

[Richard Crowley]

pay the electrician and save yourself all that headache.

And then you have the option:
1) Get a matching "dryer cord" to plug into the electrician-installed outlet, and make an "adapter cable" to the special euro-connector.
2) Exchange the US receptacle for the euro-connector.

[IanB]

I think the IEC connector will be available in two variants. One variant to be attached to the end of a flexible cable like an extension cord. The other variant to be wall mounted as a fixed installation. If it were me I would go with the extension cord/adapter approach, as it is overall more flexible (no pun intended).

[Spork Schivago]

IMHO you would be well served by a good book on electrical wiring, I have a copy of this https://www.amazon.com/Wiring-House-5th-Pros/dp/162710674X and have found it to be well written and has a lot of helpful tips and tricks.

The breaker is there to protect the wire, so it's perfectly ok to use wire larger than required, for example 12AWG on a 15A breaker but you CANNOT go the other way, eg 14AWG on a 20A breaker. It's also perfectly ok to use a larger capacity circuit than required by the load, so a 40A circuit is just fine for a load only requiring 20A so long as the wire is adequately sized for the breaker, 8AWG for 40A.

Yes, a good book on electrical wiring is much needed.   I have the DC down pretty well, but the AC I still struggle with.   Not so much the 120VAC or the 240VAC, but the 3 phase, stuff like that.

I wasn't getting hung up on the neutral / hot thing like IanB suspected.   It was the fact that the unit has two 16-amp breakers.    So I was looking at it like two totally different circuits inside the PDU, sharing a common ground.    When I say 16-amp, I believe, again, these are de-rated, so they'd be equivalent to our (USA) 20-amp.    I kept on thinking the neutral would power the bottom outlets, the L/+ would power the upper ones.   Or the L/+ would power the first breaker, the neutral the second.   That's what was messing with me.

I purchased a small book called Ugly's Electrical References, 2017 Edition, but that's a reference book.    Thanks for the link!    Once I get this ER thing taken care of and find out what's wrong with me, I'll sit down and learn more about the different types of wires.   I understand the gauges and what gauge to use for what size breaker, but there's information that I still lack.   For example, what's a grounding loop?   How to prevent a grounding loop?   And then this issue.   Running 120VAC down the neutral threw me for a loop at first, until I started thinking about it.   In reference to ground, we'll have 240VAC.   We'll have a complete path back to the panel, so the circuit will be complete.   I'll still be grounding the PDU with the external ground.   I just have to pick the wire now.

8/2 with ground or 8/3 without...in the technical drawing for the receptacle I'm purchasing (a wall-mount one), it show all three wires being stripped....so I'm leaning towards 8/3 without ground.   But I don't think it'll make a difference operational wise.

I'm not sure about the conduit though.   I want to mount the receptacle on the cement wall, like the other ones are, and run conduit up to the floor joists, then just run the wire through the first floor floor joists, like the electrician did.   But I'm not sure if the conduit at Home Depot and Lowes is going to match up to the European style outlet there...I might need some sort of adapter for that.

[Spork Schivago]

The reason why the professional electricians can't accommodate the plug is that they're not allowed to wire in the European socket.  They must use sockets that are allowed for permanent installations in North America, which are pretty much NEMA sockets.  So have them wire in a dryer socket (30A) or a range socket (40A), then construct an adapter made with a dryer or range plug to your European socket. 
If you go out early on garbage day with a set of wire cutters, you can get the plug extra cheap. 

They can't do it because it's against the NEC?   As in I cannot legally do it either because it's against code?

This might explain the drastic price difference between the sockets over in Europe and the same sockets that say they're rated for North America.   The European ones are around 4 to 7 of their funky dollars (the L / F pound thing).   But the North American ones that I've seen are usually 100$ USD +.

Depends on your local laws, rules and regulations about legality... In my area, I am allowed to make changes in my house to electrical circuits, but, if a fire developed from a mistake in my wiring, AND the insurance company found out, the house is not covered under the rules of insurance, so therefore, I just ate it...

Since you are not knowledgeable about wiring, pay the $100 for the outlet, wire it up to local codes/standards/components, pay the electrician and save yourself all that headache.

Just my 2 cents...

I will admit that I lack knowledge in the NEC, but running some 8 gauge wire isn't going to be an issue.   I don't usually play with 240VAC, but when I do, I've always wired it the way everyone else does.    I've just never seen a receptacle that expected one 240VAC line, one neutral, one ground.   I think I'll be alright.

And in my county, we have to get a permit before we begin work like this and have it inspected, so I know it'll be up to code, one way or another.   I'd rather just make sure I purchase the proper stuff and have a full understanding of what I'm doing before I continue.   For example, if I hadn't come here and purchased that double pole 20-amp breaker, that would have never have passed the inspection, I would have wasted money on the 12/2 or 12/3, and the breaker, and would have to start all over again.

Thank you for the concern though.

[tpowell1830]

The reason why the professional electricians can't accommodate the plug is that they're not allowed to wire in the European socket.  They must use sockets that are allowed for permanent installations in North America, which are pretty much NEMA sockets.  So have them wire in a dryer socket (30A) or a range socket (40A), then construct an adapter made with a dryer or range plug to your European socket. 
If you go out early on garbage day with a set of wire cutters, you can get the plug extra cheap. 

They can't do it because it's against the NEC?   As in I cannot legally do it either because it's against code?

This might explain the drastic price difference between the sockets over in Europe and the same sockets that say they're rated for North America.   The European ones are around 4 to 7 of their funky dollars (the L / F pound thing).   But the North American ones that I've seen are usually 100$ USD +.

Depends on your local laws, rules and regulations about legality... In my area, I am allowed to make changes in my house to electrical circuits, but, if a fire developed from a mistake in my wiring, AND the insurance company found out, the house is not covered under the rules of insurance, so therefore, I just ate it...

Since you are not knowledgeable about wiring, pay the $100 for the outlet, wire it up to local codes/standards/components, pay the electrician and save yourself all that headache.

Just my 2 cents...

I will admit that I lack knowledge in the NEC, but running some 8 gauge wire isn't going to be an issue.   I don't usually play with 240VAC, but when I do, I've always wired it the way everyone else does.    I've just never seen a receptacle that expected one 240VAC line, one neutral, one ground.   I think I'll be alright.

And in my county, we have to get a permit before we begin work like this and have it inspected, so I know it'll be up to code, one way or another.   I'd rather just make sure I purchase the proper stuff and have a full understanding of what I'm doing before I continue.   For example, if I hadn't come here and purchased that double pole 20-amp breaker, that would have never have passed the inspection, I would have wasted money on the 12/2 or 12/3, and the breaker, and would have to start all over again.

Thank you for the concern though.

It is probably my fault for not being clear, but what I was getting at is that the electrician will not wire up your Euro plug, however, he will wire up a receptacle, up to code and where you want it, if you use the US 40 amp receptacle, and then you can create the adapter cable as Mr. Crowley says here:

And then you have the option:
1) Get a matching "dryer cord" to plug into the electrician-installed outlet, and make an "adapter cable" to the special euro-connector.
2) Exchange the US receptacle for the euro-connector.

If you feel comfortable installing the standard US receptacle, no worries, you seemed confused about it in your posts. This gives you a standard US 220/240VAC receptacle power source that you might use for something else (if needed) using standard US plugs. You can make the adapter cable yourself to the Euro connector, which is fairly simple. I now understand your confusion about 240 VAC with neutral v. 220/240VAC with 2 wires. You seem to understand that now.

So then you would have a std US 220/240VAC receptacle, a std US plug on your adapter cable, the cable itself (probably SOOW style) to the Euro receptacle that plugs into your device.

Hope this helps...

[Monkeh]

Why piss about with an adapter when you could just put the (in)appropriate plug on the cable?

[IanB]

Why piss about with an adapter when you could just put the (in)appropriate plug the cable?

Also some versions of the PDU come with detachable power cords.

[Monkeh]

Why piss about with an adapter when you could just put the (in)appropriate plug the cable?

Also some versions of the PDU come with detachable power cords.

Uncommon at these current ratings due to connector size.

[james_s]

One good reason to use an adapter is code compliance. As far as I know installing a foreign receptacle doesn't meet code, but it's perfectly legal to use an adapter. Whether or not this makes logical sense isn't really the issue, but if one decides to pay an electrician to install something it normally has to be done per code.

[Monkeh]

One good reason to use an adapter is code compliance. As far as I know installing a foreign receptacle doesn't meet code, but it's perfectly legal to use an adapter. Whether or not this makes logical sense isn't really the issue, but if one decides to pay an electrician to install something it normally has to be done per code.

... no, why not just remove the 'foreign' plug from the cable and just put one of your unfortunate contraptions on and be done with it? Shove the NEMA 6-30 or L6-30 on the cable and forget about playing adapter games.

[vk6zgo]

I'd void warranty if I replaced the plug. 

I very much doubt that this is true.
If the device is not useable without the original plug, it is not "fit for purpose".
Don't just assume things, check with both the manufacturer & your local laws re warranty.

The pics I uploaded have the L1 and Earth symbol (G), but doesn't list N.   This equipment cannot run off 120VAC by itself.   It's not one of those 120V or 240V.   It requires 200VAC - 240VAC to operate.   It's just a Power Distribution Unit for a server rack.   A horizontal, metered one, made by Hewlett Packard Enterprise (or at least they outsourced someone to make it for them).

In the past, many US manufacturers made equipment for 240volt service.
Amateur radio linear amplifiers are, most often designed for 240v supplies, as it is difficult to source enough
power from the 120v Mains.

All the older, (pre-SMPS) US made stuff used in 240v countries used either of two approaches:-
Two transformer primaries which could be used in parallel for 120v, or, in series for 240v.

In both cases, the 240v wiring was built to US standards for their "split phase" 240v system, & normally used a DPST switch &  fuses in both sides (hot & hot for the US system, & hence hot & neutral for, for instance, the Australian one)
Fusing the Neutral is technically against the rules in Oz, but there were plenty of  US sourced units used in this country which did this.

Australian or European equipment will operate quite happily in the USA, in that it is designed so that both sides are regarded as "hot" (that way, if your power socket is wired with A & N reversed, insulation ratings are maintained).

One trap, is that non US standard 240v stuff may not have a DPST switch, & will, almost certainly, only fuse the Active side of the Mains.

If your device is from HP, it probably does conform with US standards.

[Gregg]

I have been following this thread since I posted and there is a lot of confusion that would be a lot clearer if you just posted exactly what it is that you are trying to power. If you don’t have it yet, post some links. 
I believe that all of the IEC 60309 plugs can be easily taken apart and removed from the power cord and reinstalled if necessary without anyone being the wiser.
It is good that you bought the 40 amp two pole breaker and are going to wire it with 8ga wire.  Most 120/240 volt breakers are only rated for continuous loads of 80% of their advertised rating.
If the device has sub breakers that are single pole, perhaps they can be changed to two pole.  Or post some pictures here with details and we may be able to help make it compliant in intent if not with actual approved breakers and wiring techniques. 
Is this going to be in some location that needs to be UL listed?  If so you are in for a rough and expensive time; I’ve been there.

[Bratster]

He has already given the model of the device twice, it's a rack mount power distribution unit.

HPE P9S16A PDU

I think that is the elephant in the room that's not being talked about, will this device still be safe if it is fed two Lines as opposed to a line and a neutral.

With the OP so concerned about changing the plug voiding the warranty, I think he is missing the bigger issue, will feeding this pdu two lines void the warranty?

And besides that will it even be safe?


Sent from my Moto x4 using Tapatalk

[Gregg]

Sorry I missed the actual device.  The problem is the single pole 16 amp breakers
I think I would have gone with two of the P9S13A PDUs and saved a lot of trouble

[vk6zgo]

He has already given the model of the device twice, it's a rack mount power distribution unit.

HPE P9S16A PDU

I think that is the elephant in the room that's not being talked about, will this device still be safe if it is fed two Lines as opposed to a line and a neutral.

With the OP so concerned about changing the plug voiding the warranty, I think he is missing the bigger issue, will feeding this pdu two lines void the warranty?

I see no reason whatsoever for it to void the warranty.
The internal circuitry has no way of knowing whether it is being run off 240v between Active & Neutral, or 240v across the secondary of a pole transformer, & will operate in the same manner in both cases.

And besides that will it even be safe?
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The insulation between "hot" & ground will be under less stress (120v instead of 240v), so that will not cause any safety issues.

The only possible safety problem would be if the device only uses an SPST Mains switch, so that one leg of the supply will still present 120v w.r.t ground inside the device.

[Bratster]

He has already given the model of the device twice, it's a rack mount power distribution unit.

HPE P9S16A PDU

I think that is the elephant in the room that's not being talked about, will this device still be safe if it is fed two Lines as opposed to a line and a neutral.

With the OP so concerned about changing the plug voiding the warranty, I think he is missing the bigger issue, will feeding this pdu two lines void the warranty?

I see no reason whatsoever for it to void the warranty.
The internal circuitry has no way of knowing whether it is being run off 240v between Active & Neutral, or 240v across the secondary of a pole transformer, & will operate in the same manner in both cases.

And besides that will it even be safe?
Sent from my Moto x4 using Tapatalk

The insulation between "hot" & ground will be under less stress (120v instead of 240v), so that will not cause any safety issues.

The only possible safety problem would be if the device only uses an SPST Mains switch, so that one leg of the supply will still present 120v w.r.t ground inside the device.

Except this is not just one device, it is a power distribution unit, so it is supplying power to multiple devices.

If it is expecting only one hot line, and it only provides circuit protection on that one line, then you have 120v on the neutral wire of each outlet with the full 32-40amps available.



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[Towger]

There are a lot of worrying posts on this thread.

It is a PDU https://www.senetic.co.uk/product/P9S16A

He can't connect it to a two 240v phase supply without a neutral with its standard blue 32a plug, if the items plugged into it (if American and using C13/C14/C16 plugs) will expect 120v.

[Richard Crowley]

According to this document: https://h20195.www2.hpe.com/v2/GetDocument.aspx?docname=a00002909enw
That PDU has the option of 14 different input plugs (including flying leads with no plug attached)
HOWEVER, note that the same model with North American NEMA plugs are DE-RATED

NOTE: All Input Circuit Ratings for NA/JP models have been de-rated according to NEC requirements
https://h20195.www2.hpe.com/v2/GetDocument.aspx?docname=a00002909enw  page 8

It is not at all clear why an EU model was specified for use in North America.
It is not at all clear what kind of (presumably 230V) loads will be plugged into this PDU?

I see NO evidence that this product was designed to accomodate "split phase" power input.
I would NOT want to connect this PDU (or the downstream loads) which may very well assume single-phase, ground-potential neutral.
The specifications clearly state "SINGLE PHASE" even for the 200-208V and the 220-240V versions.

This is a much bigger can of worms than the simplistic question about wiring a receptacle.


Ref: https://h20195.www2.hpe.com/v2/GetDocument.aspx?docname=a00002909enw

[Spork Schivago]

Why piss about with an adapter when you could just put the (in)appropriate plug the cable?

Also some versions of the PDU come with detachable power cords.

This has a nut on the end, but I unscrew the nut, and the wire is not detachable.   I checked that first, hoping it was detachable.

[Spork Schivago]

One good reason to use an adapter is code compliance. As far as I know installing a foreign receptacle doesn't meet code, but it's perfectly legal to use an adapter. Whether or not this makes logical sense isn't really the issue, but if one decides to pay an electrician to install something it normally has to be done per code.

... no, why not just remove the 'foreign' plug from the cable and just put one of your unfortunate contraptions on and be done with it? Shove the NEMA 6-30 or L6-30 on the cable and forget about playing adapter games.

What gets me, this PDU isn't listed as a European PDU.   It's listed as International, and according to HPE, it _can_ be used in the USA or Europe...which makes me think perhaps that's why the neutral isn't listed as neutral on the physical plug itself, just Earth and L/+ is listed...it leans more towards a European PDU than a North American one though, if that makes sense.   The plug it's using is common over there, the built-in breakers show the derated values of the breakers, the plug itself shows the derated value of the plug (breakers shouldn't continuously handle a load more than 80% of what they're rated for, that 80% is called the derated value, and everything here shows the derated value (80% of 20 is 16, 80% of 40 is 32.   The two breakers both show 16-Amp, the plug shows 32-Amp)).

[Monkeh]

It can be used in the USA - on a single phase 208V supply. Not a split-phase 240V one, preferably.

The plug it's using is common over there, the built-in breakers show the derated values of the breakers, the plug itself shows the derated value of the plug (breakers shouldn't continuously handle a load more than 80% of what they're rated for, that 80% is called the derated value, and everything here shows the derated value (80% of 20 is 16, 80% of 40 is 32.   The two breakers both show 16-Amp, the plug shows 32-Amp)).

Bollocks. That's the American approach to breakers and that is not how they are rated in the rest of the world. A 16A breaker carries 16A continuous. A 32A plug handles 32A continuous. Those are not deratings, they are ratings.

[Richard Crowley]

Bollocks. That's the American approach to breakers and that is not how they are rated in the rest of the world. A 16A breaker carries 16A continuous. A 32A plug handles 32A continuous. Those are not deratings, they are ratings.

According to the horses' mouth (the HPE document I cited) it is DERATED because of the NEMA connector capacity, not the capacity of the site wiring or circuit breaker rating.

[Monkeh]

Bollocks. That's the American approach to breakers and that is not how they are rated in the rest of the world. A 16A breaker carries 16A continuous. A 32A plug handles 32A continuous. Those are not deratings, they are ratings.

According to the horses' mouth (the HPE document I cited) it is DERATED because of the NEMA connector capacity, not the capacity of the site wiring or circuit breaker rating.

That particular derating I can't speak to. I would rather not need to remove and incinerate my eyes after looking at NEMA connectors further.

[Spork Schivago]

I'd void warranty if I replaced the plug. 

I very much doubt that this is true.
If the device is not useable without the original plug, it is not "fit for purpose".
Don't just assume things, check with both the manufacturer & your local laws re warranty.

See, here, you're assuming that I'm assuming things.   There is a sticker that breaks if the PDU is opened, and the sticker says WARRANTY VOID IF STICKER IS REMOVED.   I believe there's a screw under that sticker, although I haven't checked.   I'm pretty sure that sticker also means if it's been poked through with a screwdriver to tear the unit apart.   Think about it.   We have a lot of current here.   Would you want to warrant a device like that if people tore it open and changed things around?   Probably not.   I know I wouldn't.

The pics I uploaded have the L1 and Earth symbol (G), but doesn't list N.   This equipment cannot run off 120VAC by itself.   It's not one of those 120V or 240V.   It requires 200VAC - 240VAC to operate.   It's just a Power Distribution Unit for a server rack.   A horizontal, metered one, made by Hewlett Packard Enterprise (or at least they outsourced someone to make it for them).

In the past, many US manufacturers made equipment for 240volt service.
Amateur radio linear amplifiers are, most often designed for 240v supplies, as it is difficult to source enough
power from the 120v Mains.

All the older, (pre-SMPS) US made stuff used in 240v countries used either of two approaches:-
Two transformer primaries which could be used in parallel for 120v, or, in series for 240v.

In both cases, the 240v wiring was built to US standards for their "split phase" 240v system, & normally used a DPST switch &  fuses in both sides (hot & hot for the US system, & hence hot & neutral for, for instance, the Australian one)
Fusing the Neutral is technically against the rules in Oz, but there were plenty of  US sourced units used in this country which did this.

Australian or European equipment will operate quite happily in the USA, in that it is designed so that both sides are regarded as "hot" (that way, if your power socket is wired with A & N reversed, insulation ratings are maintained).

One trap, is that non US standard 240v stuff may not have a DPST switch, & will, almost certainly, only fuse the Active side of the Mains.

If your device is from HP, it probably does conform with US standards.
[/quote]

Thank you for that information there.   Like I just recently said in a previous post (that you couldn't have read before writing this), HPE does list this PDU as being International, not European, and claim that it _can_ be used in the US, so I think you're right there and it does conform with US standards.    I think that's why I have the external grounding screw.   The installation documents says it might not be used in some circumstances (they word it a bit differently, like if your situation requires the use of an external ground, run a 10 gauge grounding wire from the screw to your rack, something like that)

[Monkeh]

I'd void warranty if I replaced the plug. 

I very much doubt that this is true.
If the device is not useable without the original plug, it is not "fit for purpose".
Don't just assume things, check with both the manufacturer & your local laws re warranty.

See, here, you're assuming that I'm assuming things.   There is a sticker that breaks if the PDU is opened, and the sticker says WARRANTY VOID IF STICKER IS REMOVED.   I believe there's a screw under that sticker, although I haven't checked.   I'm pretty sure that sticker also means if it's been poked through with a screwdriver to tear the unit apart.   Think about it.   We have a lot of current here.   Would you want to warrant a device like that if people tore it open and changed things around?   Probably not.   I know I wouldn't.

You don't have to take that sticker off or open the unit to change the plug. You just remove the plug from the cable.

But again, this isn't really a suitable device for a split-phase installation.

[Spork Schivago]

I have been following this thread since I posted and there is a lot of confusion that would be a lot clearer if you just posted exactly what it is that you are trying to power. If you don’t have it yet, post some links. 
I believe that all of the IEC 60309 plugs can be easily taken apart and removed from the power cord and reinstalled if necessary without anyone being the wiser.
It is good that you bought the 40 amp two pole breaker and are going to wire it with 8ga wire.  Most 120/240 volt breakers are only rated for continuous loads of 80% of their advertised rating.
If the device has sub breakers that are single pole, perhaps they can be changed to two pole.  Or post some pictures here with details and we may be able to help make it compliant in intent if not with actual approved breakers and wiring techniques. 
Is this going to be in some location that needs to be UL listed?  If so you are in for a rough and expensive time; I’ve been there.

I've posted this multiple times, what unit I'm dealing with.   You might have missed it.   I posted it early on and then again when someone referred to it as a mystery device.   It's the HPE P9S16A, which is a HPE G2 Switched 7.3kVA/60309 3-wire 32A/230V Outlets (12) C13 (4) C19/2U Horizontal INTL PDU.   Here is a link, I hope this helps https://www.hpe.com/au/en/product-catalog/servers/power-distribution-units/pip.specifications.power-distribution-units.1009830086.html

I generally don't like posting links, because that link will probably be dead in a few years, if that.

This PDU is in my rack, currently, just not wired up.   My server rack.   I mentioned that because PDU can refer to multiple things and I didn't want any confusions.   I've always been a system programmer, but I started switching carriers maybe a decade ago.   I got into repair.   Over time, I started learning a lot about hardware and DC.   I did a lot of reading, and now I've made a circuit board.   We have started an official company.   We're still in the process and have to fill out a DBA once our Articles finish running in the news paper.   We've invested a lot of money on hardware, software, upgrading the electrical panel in the house, etc.   We are currently going to run the business out of our house.

I posted pics of the plug, but for some reason, they didn't seem to get uploaded, I can try again.    Replacing the plug itself puts us in the same predicament that we're in now.   That plug only has three pins, therefore, it only has three wires inside running to those three pins.

It's not like I can just through a NEMA twist-and-lock plug on there and wire it up properly.   The wire itself would be what would limit us.   So, the only way to really properly put a NEMA twist-and-lock plug on it or something similar, would be to tear the unit apart and see how they have the actual cable wired up, and see if I can wire it differently, where it accepts two 120VAC's, but from reading everyone's responses, it seems that it might already be wired like that.   240VAC going down the L/+ pin, or 120VAC going down the L/+ pin, 120VAC going down the Neutral pin.

You guys have been extremely helpful and I really appreciate you guys taking the time to help me learn something new and make sure I'm up to code.    I'm back from the ER, and good news is I don't have anything horrible.   They believe my drastic weight loss is simply due to the high level of stress that I'm under.   The business is a new type of stress, but it's a good stress, that I have control over.   I break everything up into smaller tasks.   Each task causes a bit of stress, but when it's finished, that stress is gone.   There is a lot going on in my life or that has recently gone on that I have no control over (my parents are both in the process of dying, my best friend killed himself in my backyard and the local police made me watch on my HD-DVR "because they didn't know how to use the DVR").   There's more than that, but this thread isn't about my stress and my life.   Just wanted to say that I think being worried like I was, was definitely affecting my thinking, and now that I know there's nothing really wrong with me, I'm back to being able to concentrate and think a lot more clear like.

[Spork Schivago]

He has already given the model of the device twice, it's a rack mount power distribution unit.

HPE P9S16A PDU

I think that is the elephant in the room that's not being talked about, will this device still be safe if it is fed two Lines as opposed to a line and a neutral.

With the OP so concerned about changing the plug voiding the warranty, I think he is missing the bigger issue, will feeding this pdu two lines void the warranty?

And besides that will it even be safe?


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Changing the plug, again, doesn't fix the problem.   The cord still only has three wires, just like the plug.    However, you bring up a valid point, and I will call HPE to double check that this unit is truly meant to be used in the USA.   I have noticed, depending on who you talk to at some of these larger companies, you're given conflicting information.   In the beginning, a Microsoft Sales rep said we could just use Windows Home editions to run the business!   That's a no.   Now, Microsoft and a Microsoft reseller are fighting over whether we can legally have Windows 10 Enterprise E3 with the Cloud Service Provider agreement installed on the local workstations / servers or if they need to be hosted somewheres not on-premise.   We're currently going with what the reseller said, and hopefully he's right.   But multiple times, Microsoft, as one, has provided us with conflicting information, depending on who we've talked to.   Calling HPE is just a phone call.   Doesn't hurt to double check.

To properly replace the plug, I'd have to open the unit, which will void warranty, and replace the actual cord as well as the plug.   If that's the only way to keep it up to code, to keep it safe, I would rather void the warranty and do that than risk burning the house down.   Our options for HPE PDUs are limited to literally only this one, with the features that feel we _need_.   There was one we wanted, that had extra features, but they only made it in three-phase.   After talking to the professional electrician, it would cost over 50,000$ to run 3-phase to our house (which I think is kinda B.S., personally, but eh).   He says there's no 3-phase on our street.   I'm not an expert on power lines, but to me, the pole out back really looks like three-phase.   I can upload pics of that.

3-phase would cost money, but would open the doors a bit for us.   But then we'd have to send back all the PSUs and order 3-phase ones, and that opens a whole nother can of worms.

[Monkeh]

Replacing the plug itself puts us in the same predicament that we're in now.   That plug only has three pins, therefore, it only has three wires inside running to those three pins.

Which is fine, if it were suited to split-phase supply, because you could just put a NEMA plug on and use a normal NEMA socket, and off you go.

It's not like I can just through a NEMA twist-and-lock plug on there and wire it up properly.   The wire itself would be what would limit us.   So, the only way to really properly put a NEMA twist-and-lock plug on it or something similar, would be to tear the unit apart and see how they have the actual cable wired up, and see if I can wire it differently, where it accepts two 120VAC's, but from reading everyone's responses, it seems that it might already be wired like that.   240VAC going down the L/+ pin, or 120VAC going down the L/+ pin, 120VAC going down the Neutral pin.

It is not wired like that. It almost certainly only has single pole breakers - this is not suitable for a split-phase system.

You cannot use this PDU safely with a split-phase supply. If 240V operation is desired you will need to use smaller PDUs which do not require additional protection, obtain a single-phase 208V or 240V supply, or use a transformer to provide such (this is a not inexpensive lump of iron..).

[Spork Schivago]

It can be used in the USA - on a single phase 208V supply. Not a split-phase 240V one, preferably.

The plug it's using is common over there, the built-in breakers show the derated values of the breakers, the plug itself shows the derated value of the plug (breakers shouldn't continuously handle a load more than 80% of what they're rated for, that 80% is called the derated value, and everything here shows the derated value (80% of 20 is 16, 80% of 40 is 32.   The two breakers both show 16-Amp, the plug shows 32-Amp)).

Bollocks. That's the American approach to breakers and that is not how they are rated in the rest of the world. A 16A breaker carries 16A continuous. A 32A plug handles 32A continuous. Those are not deratings, they are ratings.

Let me reword it a bit.   Over in Europe, a 32A breaker is equivalent to our North American 40-Amp breakers.   Does that sense?

Here's an article I just googled that explains it better than I can.   Give it a read and let me know what you think.

http://www.raritan.com/blog/detail/rack-pdu-power-rating-vs.-load-capacity

[Monkeh]

It can be used in the USA - on a single phase 208V supply. Not a split-phase 240V one, preferably.

The plug it's using is common over there, the built-in breakers show the derated values of the breakers, the plug itself shows the derated value of the plug (breakers shouldn't continuously handle a load more than 80% of what they're rated for, that 80% is called the derated value, and everything here shows the derated value (80% of 20 is 16, 80% of 40 is 32.   The two breakers both show 16-Amp, the plug shows 32-Amp)).

Bollocks. That's the American approach to breakers and that is not how they are rated in the rest of the world. A 16A breaker carries 16A continuous. A 32A plug handles 32A continuous. Those are not deratings, they are ratings.

Let me reword it a bit.   Over in Europe, a 32A breaker is equivalent to our North American 40-Amp breakers.   Does that sense?

Not really, no, because trip characteristics don't necessarily work like that. But it doesn't matter anyway.

[Richard Crowley]

You could have your electrician wire one of these into the circuit that you install for PDU.
This will provide a true single-phase (neutral at ground-potential) 240V power circuit.

• Input Voltage: 240/480VAC
• Output Voltage: 120/240VAC
• VA Rating: 7.5KVA
• $605.49 /EA
• Item ships from Zoro in 1 business day.
  This item ships FREE

https://www.zoro.com/acme-electric-transformer-75kva-120240v-wall-t2535153s/i/G2253343/#specifications

[dmills]

The P9S13A and 14A have double pole breakers for 240V split phase service (Or I assume 208V two legs plus neutral from a 120V three phase supply), see the quickspecs sheet.

The P9S16A has only single pole breakers for 230V service with an earthed neutral, it is NOT suitable for 240V split phase service or 208V two phase plus neutral.

You have the wrong PDUs for your supply, send em back and get the right ones. 

You could use an isolating transformer to produce a (UK parlance warning) "Separately derived supply", which would give you 230V with an earthed neutral but the NEC may have things to say about this.

Regards, Dan.

[Spork Schivago]

The P9S13A and 14A have double pole breakers for 240V split phase service (Or I assume 208V two legs plus neutral from a 120V three phase supply), see the quickspecs sheet.

The P9S16A has only single pole breakers for 230V service with an earthed neutral, it is NOT suitable for 240V split phase service or 208V two phase plus neutral.

You have the wrong PDUs for your supply, send em back and get the right ones. 

You could use an isolating transformer to produce a (UK parlance warning) "Separately derived supply", which would give you 230V with an earthed neutral but the NEC may have things to say about this.

Regards, Dan.

If I had the wrong one, which would be the correct one to purchase with the same features (same load capacitance, switched, etc.?)   I talked to my European friend and he said it's just a language barrier and I'm supposed to run 120VAC down the L/+ and Neutral.   I've contacted my VAR and I'm supposed to send him a short email with my question so he can pass it along to the HPE techs, and then we decide if we need a conference call to answer my question(s), if the PDU won't work for my situation, or figure out how it's supposed to wired.

I didn't see any split-phased PDUs listed.   Only single-phase, and 3-phase....at least from my crappy recollection.

Thanks!

[Monkeh]

I talked to my European friend and he said it's just a language barrier and I'm supposed to run 120VAC down the L/+ and Neutral.

And if you do that you'll have a 30A or thereabouts breaker protecting wiring not rated for it.

[Spork Schivago]

I talked to my European friend and he said it's just a language barrier and I'm supposed to run 120VAC down the L/+ and Neutral.

And if you do that you'll have a 30A or thereabouts breaker protecting wiring not rated for it.

That's the question though, would I?   This is what HPE needs to answer and why we're getting them involved now.   To see if I'm supposed to wire it with 120VAC going down the L/+ pin and down the neutral pin or if I'm just supposed to have 240VAC going down the L/+ pin.   If HPE says L/+ pin, then I can try to find an equivalent, which I don't think I can, I might be able to purchase a smaller unit that produces 240VAC output and daisy chain a few together, or purchase what the one user linked me to to provide the 240VAC for L/+.   So we have a few options it looks like, depending on how HPE responds.   I've sent the email, tomorrow my VAR will forward it along, and he'll call me later in the day to see where we stand.

[Monkeh]

I talked to my European friend and he said it's just a language barrier and I'm supposed to run 120VAC down the L/+ and Neutral.

And if you do that you'll have a 30A or thereabouts breaker protecting wiring not rated for it.

That's the question though, would I?

Yes. Because it has single pole breakers.

Get the P9S13A instead. Have an L6-30 outlet installed.

[Spork Schivago]

I talked to my European friend and he said it's just a language barrier and I'm supposed to run 120VAC down the L/+ and Neutral.

And if you do that you'll have a 30A or thereabouts breaker protecting wiring not rated for it.

That's the question though, would I?

Yes. Because it has single pole breakers.

Get the P9S13A instead. Have an L6-30 outlet installed.

How do you know that those two breakers inside the unit are single-pole?   I know the plug itself is using three 8-gauge wires.   Have you seen a tear down or something or is there some way you can tell by the info that was provided?   I wonder why HPE lists this unit as International.   I can buy the whole sales talked to tech and tech was just wrong thing.   That has happened before, not with HPE, but with Microsoft, for instance.   I'm not asking this trying to be a smart ass or anything, I'm just trying to learn a little and get a better understanding.

Thanks.

[Monkeh]

I talked to my European friend and he said it's just a language barrier and I'm supposed to run 120VAC down the L/+ and Neutral.

And if you do that you'll have a 30A or thereabouts breaker protecting wiring not rated for it.

That's the question though, would I?

Yes. Because it has single pole breakers.

Get the P9S13A instead. Have an L6-30 outlet installed.

How do you know that those two breakers inside the unit are single-pole?   I know the plug itself is using three 8-gauge wires.   Have you seen a tear down or something or is there some way you can tell by the info that was provided?   I wonder why HPE lists this unit as International.   I can buy the whole sales talked to tech and tech was just wrong thing.   That has happened before, not with HPE, but with Microsoft, for instance.   I'm not asking this trying to be a smart ass or anything, I'm just trying to learn a little and get a better understanding.

Thanks.

Look at the documents Richard linked.

[Spork Schivago]

I cannot use the P9S13A's.   That's 208VAC outlets.   I need 220VAC+.

[Spork Schivago]

I've looked at that document many times, I have a copy saved.   I think my limited understanding of the AC threw me off.   You're talking about on page 8, so was Richard, right?

So, in layman's terms, could one of you guys explain to me why those 1-pole 16A breakers are an issue, versus me having two 2-pole 20A breakers?

That device Richard Crowley linked too, I call that a step-up transformer, I'm not sure what they call it, but that would safely complete the requirements to provide the necessary 240VAC single-phase that I need, correct?

Where I wouldn't be violating any codes, etc?   I want to find something with at least IP44 rating, but maybe IP67.   I dunno yet.

[Monkeh]

So, in layman's terms, could one of you guys explain to me why those 1-pole 16A breakers are an issue, versus me having two 2-pole 20A breakers?

With only a single pole breaker, one hot leg will still be protected by the upstream breaker. None of the outlets, nor the cables plugged into them, are rated for this.

Where I wouldn't be violating any codes, etc?   I want to find something with at least IP44 rating, but maybe IP67.   I dunno yet.

I can't speak to your codes. As for IP ratings, don't put it outside and you won't need IP67...

[Spork Schivago]

So, in layman's terms, could one of you guys explain to me why those 1-pole 16A breakers are an issue, versus me having two 2-pole 20A breakers?

With only a single pole breaker, one hot leg will still be protected by the upstream breaker. None of the outlets, nor the cables plugged into them, are rated for this.

Where I wouldn't be violating any codes, etc?   I want to find something with at least IP44 rating, but maybe IP67.   I dunno yet.

I can't speak to your codes. As for IP ratings, don't put it outside and you won't need IP67...

I don't plan on putting it outside, but our basement is made out of cement, and that's where it's gonna be mounted.   I'd feel a lot safer with IP67 if that wall ever started seeping through.

Do you mean one of the hot legs won't be protected by the upstream breaker?

[Monkeh]

Do you mean one of the hot legs won't be protected by the upstream breaker?

It will be protected only by the upstream breaker.

[Richard Crowley]

So, in layman's terms, could one of you guys explain to me why those 1-pole 16A breakers are an issue, versus me having two 2-pole 20A breakers?

Because the PDU is designed to have only the "L" at an elevated voltage.  The "N" is assumed to be essentially zero-potential (relative to ground).
If you wire that to a "split phase" where "L" is at 120V, AND "N" is at 120V (both relative to ground) then you are putting everything plugged into it at risk because turning off a single-phase breaker leaves the "N" side at 120V and that is VERY unsafe.

That device Richard Crowley linked too, I call that a step-up transformer, I'm not sure what they call it,

No. You can wire it "straight-across" (240V in and 240V out) in which case you could call it an "isolation transformer".
But it has many more taps on the primary (input) side, up to 400-500V so that you can tap into higher voltage sources (as in a large industrial situation). In that case you could call it a "step-DOWN" transformer.

but that would safely complete the requirements to provide the necessary 240VAC single-phase that I need, correct?

Yes. Because you can have the electrician wire the secondary (output) of the transformer for 240V, and connect one side to ground.  That makes it a single-phase, ground-referenced source which is exactly what the PDU wants.

Where I wouldn't be violating any codes, etc?

   
That is ultimately up to your electrical inspector (from the local governmental jurisdiction.)
In a public/industrial/commercial setting you may need to have a licensed professional engineer "design" the circuit and approve it to satisfy the inspector.

I want to find something with at least IP44 rating, but maybe IP67.   I dunno yet.

Many/most large transformers like that come in a version designed for outdoor installation.  Designed for operation in the rain, etc.  Is that what you mean?  The example I cited claims: "Enclosure Type Indoor/Outdoor", so designed to operate out in the weather.  Unless you seek something that will operate immersed?  Planning on operating during a flood?

[Spork Schivago]

So, in layman's terms, could one of you guys explain to me why those 1-pole 16A breakers are an issue, versus me having two 2-pole 20A breakers?

Because the PDU is designed to have only the "L" at an elevated voltage.  The "N" is assumed to be essentially zero-potential (relative to ground).
If you wire that to a "split phase" where "L" is at 120V, AND "N" is at 120V (both relative to ground) then you are putting everything plugged into it at risk because turning off a single-phase breaker leaves the "N" side at 120V and that is VERY unsafe.

So when HP speaks of 1-phase and lists NA/JP for the models, they're really meaning split-phase, for the higher than 120VAC PDUs, correct?   And split-phase is what we have coming into our house, not 1-phase, right?   120VAC - 0 - 120VAC.   That clears a lot of stuff up for me.

That device Richard Crowley linked too, I call that a step-up transformer, I'm not sure what they call it,

No. You can wire it "straight-across" (240V in and 240V out) in which case you could call it an "isolation transformer".
But it has many more taps on the primary (input) side, up to 400-500V so that you can tap into higher voltage sources (as in a large industrial situation). In that case you could call it a "step-DOWN" transformer.

Thank you for the clarification there!   I didn't thoroughly enough.   I understand.

but that would safely complete the requirements to provide the necessary 240VAC single-phase that I need, correct?

Yes. Because you can have the electrician wire the secondary (output) of the transformer for 240V, and connect one side to ground.  That makes it a single-phase, ground-referenced source which is exactly what the PDU wants.

I would rather try wiring it up myself, properly.   Are you familiar with the brand name at all?   Are they any good?

Where I wouldn't be violating any codes, etc?

   
That is ultimately up to your electrical inspector (from the local governmental jurisdiction.)
In a public/industrial/commercial setting you may need to have a licensed professional engineer "design" the circuit and approve it to satisfy the inspector.

When I said Where I wouldn't be violating any codes, I was speaking strictly about the NEC, not the modifications (more like additions, from how I read the rules) that my local jurisdiction (Steuben County) can make to the NEC.   Would this violate any of the NEC that all states must follow?   If I cannot get passed that, there's no point going to my local governmental jurisdiction.   As I understand it, they can add to the NEC, but they cannot remove stuff from the NEC.   So if it fails the NEC right  now, no matter where I live in the USA, no local governmental jurisdiction can modify the NEC in such a way where it'd pass.

I want to find something with at least IP44 rating, but maybe IP67.   I dunno yet.

Many/most large transformers like that come in a version designed for outdoor installation.  Designed for operation in the rain, etc.  Is that what you mean?  The example I cited claims: "Enclosure Type Indoor/Outdoor", so designed to operate out in the weather.  Unless you seek something that will operate immersed?  Planning on operating during a flood?

We do not plan on operating it immersed!   If it's ever immersed, we have bigger issues to deal with!

I read IP14 as:
1:  Any large surface of the body, such as the back of the hand, but no protection against deliberate contact with a body part.
4:  Water splashing against the enclosure from any direction shall have no harmful effect.

I read IP6<whatever> as:  No ingress of dust; complete protection against contact.

In the basement, there is dust, that's for sure.   We have a dehumidifier running 24/7 that has actually helped filter a lot of it (although, that was not the intention for which we installed it).   With a little one in the house, we keep a tight eye on her, but she is growing fast, and eventually, she'll be at that age where she'll go down into the basement.   And when I was a child, at that age (going down into the basement age, not her age), I found a green fuse and put it in a light socket, thinking it'd glow green when I pulled the string to turn on the light.    I also took a screwdriver and put it in an electrical outlet, thinking the end would light up like a lightbulb.    Neither experience was very memorable.

Here, we're dealing with a lot more current than what the light socket or receptacle could provide.   I would love to say no matter what, she'd never be in the basement unsupervised, but sooner or later, she'll have her own room.   We'll do our best to raise her, but she might sneak out at night, or go down into the basement to play, I dunno.   If you feel that IP14 rating is good enough for the basement, and she'd have to do some work to get hurt on that, then I'll go for that one.

Finally, is 7.5KVA the correct rating for this unit?   Assuming that I'm drawing the entire 7.3KVA from my PDU, and I was drawing that constantly, would that 7.5KVA transformer hold up, or should I maybe consider purchasing a larger one?   Right now, we went for 7.3KVA, but made sure we could daisy chain another PDU, if needed.   We're a start-up company, just my wife and me.   We're going to be close to the 7.3KVA already.   It gives us a little wiggle room for a few upgrades / extra equipment, but eventually, we'll need to purchase another PDU, if I've done my math correctly.   We're still a ways away from that.   The idea now is to try and make some revenue and stop spending cash in the near future.   I think we have just about everything we need, minus a few little extras (the transformer, a proper gateway, some shielded ethernet ends, etc).

Your post makes a lot more sense to me now.

[Spork Schivago]

Also, that transformer lists the input as 240,480VAC.   It also lists it as single phase.   240x480 on the primary, 120x240 on the secondary.   With it being one phase, wouldn't that put us in the same predicament that we're in now?   Or am I misunderstanding something here?

Here's a link to the datasheet:

https://www.alliedelec.com/m/d/a43930206090ced4ef847635416f7c30.pdf

So I'd connect the primary lines to H1-H3 and H2-H4, then I'd connect the secondary lines to X1 - X4?   Here's the wiring diagrams:    https://www.galco.com/techdoc/acme/t-2-53515-3s_wd.pdf

I see the interconnect for secondary volts as X2 to X3.   So I tie X2 and X3 together.....My one hot from the breaker would run from H1-H3, and then another hot would run to H2-H4?   I'd ground the transformer to one of the buss-bars.    Then just connect X1-X4 directly to the L/+ on the receptacle, using the proper sized wire, of course, right?

It seems to me, I'd run H2-H4 together and H1-H3 together, but then one set would be tied to the neutral, one to the hot....but that can't be right because it expects 240 minimum on the primary.

[Richard Crowley]

So when HP speaks of 1-phase and lists NA/JP for the models, they're really meaning split-phase, for the higher than 120VAC PDUs, correct?   

NO!!!!  Single-phase (or "1-phase")  NEVER means the same thing as "split phase"  Single-phase (at least here in North America) implies that one side ("Line") is "HOT" and the other side ("Neutral") is essentially at zero-potential (i.e. GROUND).  In North America, the convention is that Neutral (white wire) is connected to Ground (green wire) at the breaker panel.  And the equipment is designed on the assumption that Neutral will be effectively at zero volts.  If you connect it to 120V you are just asking for trouble.

And split-phase is what we have coming into our house, not 1-phase, right?   120VAC - 0 - 120VAC. 

Each side (120VAC to neutral/ground) is a "1-phase" circuit.  What you have coming into your house (and virtually everyone's house in North America) are two "single-phase" circuits.  You can get 240V from one "phase" to the other because of the North American convention established long before we were born.  But those two sides are not REALLY "phases".  Electricians call them "phases", but electronic engineers do NOT call them "phases" because they are not.

Appliances that are designed to operate on 240V in North America are designed to have the two 120V sides at 120V above ground.  They are typically resistive heaters (water heaters, forced air furnaces, cook-stoves, ovens, etc.)  And BOTH sides are well insulated and assumed to be always HOT. 

But what you have is a piece of industrial equipment that was designed with the assumption that it would be connected to a source of GROUND_REFERENCED 240V. That is what THEY mean by "single-phase".  Your PDU was designed on the assumption that the Neutral line will be essentially zero volts.  Connecting it to 120V is a monumentally terrible idea.  Before you identified what your mystery load was, we were assuming that it was some kind of gadget that might operate on "split-phase power.  Perhaps a domestic welder or air-compressor, etc.

But you have a sophisticated piece of industrial equipment which has a bunch of sensitive and expensive loads (computers) connected to it. And that is a whole different ball-game.

I would rather try wiring it up myself, properly.

 
By operating a business in your home, you create a hugely gray area.  Technically you should take out a permit and have an inspection.  Else your can cancel your fire insurance because they won't pay off if you have done something like this and your house goes up in flames.  Be sure and have a good off-site daily backup/archive scheme in operation.

Are you familiar with the brand name at all?   Are they any good?

I would feel perfectly comfortable using that transformer if I were in the position of needing something like that.  If you have any qualms, be sure and buy a transformer with proper approval stamps (UL, etc.)  See Dave's recent video on this topic.

When I said Where I wouldn't be violating any codes, I was speaking strictly about the NEC, not the modifications (more like additions, from how I read the rules) that my local jurisdiction (Steuben County) can make to the NEC.   Would this violate any of the NEC that all states must follow?   If I cannot get passed that, there's no point going to my local governmental jurisdiction.   As I understand it, they can add to the NEC, but they cannot remove stuff from the NEC.   So if it fails the NEC right  now, no matter where I live in the USA, no local governmental jurisdiction can modify the NEC in such a way where it'd pass.

That is why getting a plan from a licenced professional engineer will help you do something that is legal.

You won't find big industral transformers like that with "IP" ratings.  They are designed for harsh, outdoor conditions.  They are not designed to be impervious to water, they are designed to operate with rain-water washing through them.  I can't imagine that there is any condition in your basement that would exceed what they would face every day outdoors. Of course, this assumes proper installation where the outer case is very well bonded go a good earth ground.  Because the transformer is completely enclosed in a ground steel case, it should be safe from animals and children.

Finally, is 7.5KVA the correct rating for this unit? 

Dunno?  What is the power rating of the (unidentified) loads NOW?  What are your expansion plans?  If you are already starting out with 5KW load, then perhaps it might be wiser to get a 10KVA (or 15KVA) transformer.

 Of course, this also begs the question how much power do you have coming into your house from the electric utility?  Typical domestic service that I have seen is 240V @ 200A which is 48KVA (minus what the rest of your house uses).  Do you have/need air-conditioning for all this?  Remember that when it comes down to it, a computer is just a really expensive heater.  If your computer uses 1000W, then you need enough air conditioning for a 1000W heat source.  So a rule of thumb is to plan on enough power to keep everything cool as well as powering it.

[Richard Crowley]

Also, that transformer lists the input as 240,480VAC.   It also lists it as single phase.   240x480 on the primary, 120x240 on the secondary.   With it being one phase, wouldn't that put us in the same predicament that we're in now?   Or am I misunderstanding something here?

That is a single-phase transformer.  There is only one core.  Than makes it single phase.  All the input (primary) and output ( secondary) wires are isolated from ground so that you can connect it whichever way you need.  You can connect the primary to anything from 216 to 504 volts.  And you can wire the secondary for either 120V or 240V.

So I'd connect the primary lines to H1-H3 and H2-H4, then I'd connect the secondary lines to X1 - X4?

No, you will blow up the transformer and burn down your house if you do that.

You need a straight-across, 1:1 transformer from your 240V "split-phase" source to a 240V, ground-referenced single-phase output.

The table shows that for 240V input, one side goes to H1 and H7 connected together, and the other side goes to H10 and H4 connected together
And the table shows the for 240V output it comes from X1 and X4, with X2 and X3 connected together.

If you connect X1 to ground, then X1 becomes "Neutral" and X4 is the source of your ground-referenced 240V SINGLE PHASE.

Please note that I am NOT a professional electrician, and I am not a licensed practicing engineer.  You should seek competent advice from a professional licensed in your jurisdiction.  High-power engineering advice, like legal advice is never completely reliable from a stranger on the internet.  Just common sense.

[Gregg]

I cannot use the P9S13A's.   That's 208VAC outlets.   I need 220VAC+.

The HPE P9S13A shows on page 8 of the HPE G2 Switched Power Distribution Units.PDF as having input of 1-ph 200-240V 24 amps with L6-30P plug on the cord.  It has the same footprint, the same outputs as the P9S16A.  The two are probably exactly the same except for input cable, plug and internal breakers. 
There is zero chance that the P9S13A can magically reduce the input voltage of 240 down to 208 volts.
The HPE website is anything but user friendly and seems like it is a product of marketing with almost total disregard for engineering; in other words, business as usual.  The places that state it is 200-208V are most likely cut and paste errors by the person that made the document.

[Richard Crowley]

The places that state it is 200-208V are most likely cut and paste errors by the person that made the document.

208V is a very common mains voltage in 3-phase power distribution.  As is 277V. 
They seem odd to us who mainly see single-phase utility power.

[C]

With
P9S16A
HPE G2 Swtd 7.3kVA/60309 2U INTL PDU

In the USA in a house, I see one of three things happing.

1. You burn your house down and insurance will not cover loss.
2. You get someone hurt, probably criminal charges.
3. You destroy some equipment.

HP lists four major categories of models

220-240V Input, Single Phase, International
Not a standard in USA.

200-208V Input, Single Phase, North America/Japan
Is using one phase of a three phase power source. Only industrial not in a house.

100-240V Input, Single Phase, Worldwide

This only matches the 110-120 used in USA.
And
HP makes a model for this
100-120V Input, Single Phase, North America/Japan

USA's 220-240Volt house standard does not match any of above.
As has been stated many times it is split phase with two hots and a common or center tap.

So the outlets of P9S16A with a transformer will still be non-standard in the USA and that will probably get someone/thing hurt!

C

[Bratster]

Also one thing to keep in mind regarding the term International, it doesn't always mean the world.

If it's a US company using the term International it's can mean the rest of the world, not the US.

HPE may be using the term in that sense,
So that power distribution unit is intended for everywhere but the US.

And I would think it's just a typo on their part that the 208 volt USA model wouldn't also be able to do 240 volt USA.
But again that's up to them to answer.

Sent from my Moto x4 using Tapatalk

[dmills]

Almost certainly the "208V" model is the one you want for a 240V split phase service, but you will need to check that with HP (It also has the US plug that your sparks should be happy to install a socket for).

It will output 240V split phase (No neutral) just the same as it is input, these are not any kind of voltage converter, just breakers relays and load measurement hardware. 

Regards, Dan.

[Spork Schivago]

So when HP speaks of 1-phase and lists NA/JP for the models, they're really meaning split-phase, for the higher than 120VAC PDUs, correct?   

NO!!!!  Single-phase (or "1-phase")  NEVER means the same thing as "split phase"  Single-phase (at least here in North America) implies that one side ("Line") is "HOT" and the other side ("Neutral") is essentially at zero-potential (i.e. GROUND).  In North America, the convention is that Neutral (white wire) is connected to Ground (green wire) at the breaker panel.  And the equipment is designed on the assumption that Neutral will be effectively at zero volts.  If you connect it to 120V you are just asking for trouble.

And split-phase is what we have coming into our house, not 1-phase, right?   120VAC - 0 - 120VAC. 

Each side (120VAC to neutral/ground) is a "1-phase" circuit.  What you have coming into your house (and virtually everyone's house in North America) are two "single-phase" circuits.  You can get 240V from one "phase" to the other because of the North American convention established long before we were born.  But those two sides are not REALLY "phases".  Electricians call them "phases", but electronic engineers do NOT call them "phases" because they are not.

Appliances that are designed to operate on 240V in North America are designed to have the two 120V sides at 120V above ground.  They are typically resistive heaters (water heaters, forced air furnaces, cook-stoves, ovens, etc.)  And BOTH sides are well insulated and assumed to be always HOT. 

But what you have is a piece of industrial equipment that was designed with the assumption that it would be connected to a source of GROUND_REFERENCED 240V. That is what THEY mean by "single-phase".  Your PDU was designed on the assumption that the Neutral line will be essentially zero volts.  Connecting it to 120V is a monumentally terrible idea.  Before you identified what your mystery load was, we were assuming that it was some kind of gadget that might operate on "split-phase power.  Perhaps a domestic welder or air-compressor, etc.

But you have a sophisticated piece of industrial equipment which has a bunch of sensitive and expensive loads (computers) connected to it. And that is a whole different ball-game.

I would rather try wiring it up myself, properly.

 
By operating a business in your home, you create a hugely gray area.  Technically you should take out a permit and have an inspection.  Else your can cancel your fire insurance because they won't pay off if you have done something like this and your house goes up in flames.  Be sure and have a good off-site daily backup/archive scheme in operation.

Are you familiar with the brand name at all?   Are they any good?

I would feel perfectly comfortable using that transformer if I were in the position of needing something like that.  If you have any qualms, be sure and buy a transformer with proper approval stamps (UL, etc.)  See Dave's recent video on this topic.

When I said Where I wouldn't be violating any codes, I was speaking strictly about the NEC, not the modifications (more like additions, from how I read the rules) that my local jurisdiction (Steuben County) can make to the NEC.   Would this violate any of the NEC that all states must follow?   If I cannot get passed that, there's no point going to my local governmental jurisdiction.   As I understand it, they can add to the NEC, but they cannot remove stuff from the NEC.   So if it fails the NEC right  now, no matter where I live in the USA, no local governmental jurisdiction can modify the NEC in such a way where it'd pass.

That is why getting a plan from a licenced professional engineer will help you do something that is legal.

You won't find big industral transformers like that with "IP" ratings.  They are designed for harsh, outdoor conditions.  They are not designed to be impervious to water, they are designed to operate with rain-water washing through them.  I can't imagine that there is any condition in your basement that would exceed what they would face every day outdoors. Of course, this assumes proper installation where the outer case is very well bonded go a good earth ground.  Because the transformer is completely enclosed in a ground steel case, it should be safe from animals and children.

Finally, is 7.5KVA the correct rating for this unit? 

Dunno?  What is the power rating of the (unidentified) loads NOW?  What are your expansion plans?  If you are already starting out with 5KW load, then perhaps it might be wiser to get a 10KVA (or 15KVA) transformer.

 Of course, this also begs the question how much power do you have coming into your house from the electric utility?  Typical domestic service that I have seen is 240V @ 200A which is 48KVA (minus what the rest of your house uses).  Do you have/need air-conditioning for all this?  Remember that when it comes down to it, a computer is just a really expensive heater.  If your computer uses 1000W, then you need enough air conditioning for a 1000W heat source.  So a rule of thumb is to plan on enough power to keep everything cool as well as powering it.

Because of the money we have invested in equipment at this point in time, I do not feel comfortable discussing publically what the loads are, however, if you would like to know, I would more than happy to PM you.   I would love it if one of our servers drew 1,000 watt!   That'd be nice.   As for the cooling, eventually we will get central air, but right now, being in the basement, we've kinda got lucky.   Throughout the year, it seems to maintain an almost stable temperature and is cool.   We have sensors for the rack, that monitor humidity, temperature, water / moisture, etc.

I am glad that you explained the IP rating a bit more in detail.   Going off that paper, it's easy for me to not fully understand how safe it is.   By reading the rating of IP14, I thought, oh no!   This isn't what I want at all!   But after what you said, it seems IP14 is perfect.

I'm still a bit confused about the phases here.   I understand how the 240VAC works in the US.   120VAC to neutral, 120VAC to neutral, 240VAC going from hot to hot.    I understand the breaker panel, I've studied it and the various names.   I know the ground buss-bar and neutral buss-bar's are connected with a jumper wire usually.   I know there's a hot buss bar where every other connector runs off the other incoming main line.

For example, the first single pole breaker, #1, runs off the first of the two incoming main 120VAC hot lines.   #3 (directly below it), runs off the second of the two incoming main 120VAC lines.   #5 runs off the first, etc.   This is why when we install double-pole breakers, we can get 240VAC from hot to hot, instead of just 120VAC.

If I were to somehow attempt to create my own 240VAC source by using single pole breakers #1 and #2, it shouldn't provide 240VAC, from my understanding (I've never attempted), but should provide 120VAC, because they're on the same "phase".

So, if what we have is called 1-phase, but not by electrical engineers, what is it called by electrical engineers, and what is split-phase?    I thought split phase was the whole 120VAC - Neutral (or ground) - 120VAC, giving us 240VAC....

I thought split-phase was where the hot was split between two wires, each 180 degrees out of phase.   When one was at 120VAC, the other was at -120VAC, giving us 240VAC.

Also, in the first post, I believe, I did mention that it was a PDU for my server rack, because I realize even the name PDU could mean multiple things, and it's important that you guys knew I was referring to a power distribution unit for a rack, holding expensive computer equipment.

Finally, because we are running a business, have a daughter, living in the city, etc, we will always follow the law, and get the proper permit, after drawing up our design, and have it inspected.   In the country, where we used to live, when I ran the 240VAC to my BGA rework station, we had tried, but the city inspector didn't really care about the country, which we thought was odd.   Technically, we were living in the Town of Country, not the City, but they said generally, in the country, you just wire it up or hire someone to wire it up.   They wouldn't actually come up to inspect my work.   I thought that was horrible and should have been reported.

I still want to wire the transformer myself.   I want to learn this stuff and I feel that I can do it, although I might need a little guidance.   I don't expect anyone to do my homework for me, just maybe double check my design before I take it to the city, that's what I'm hoping for.

[Spork Schivago]

Also, that transformer lists the input as 240,480VAC.   It also lists it as single phase.   240x480 on the primary, 120x240 on the secondary.   With it being one phase, wouldn't that put us in the same predicament that we're in now?   Or am I misunderstanding something here?

That is a single-phase transformer.  There is only one core.  Than makes it single phase.  All the input (primary) and output ( secondary) wires are isolated from ground so that you can connect it whichever way you need.  You can connect the primary to anything from 216 to 504 volts.  And you can wire the secondary for either 120V or 240V.

So I'd connect the primary lines to H1-H3 and H2-H4, then I'd connect the secondary lines to X1 - X4?

No, you will blow up the transformer and burn down your house if you do that.

You need a straight-across, 1:1 transformer from your 240V "split-phase" source to a 240V, ground-referenced single-phase output.

The table shows that for 240V input, one side goes to H1 and H7 connected together, and the other side goes to H10 and H4 connected together
And the table shows the for 240V output it comes from X1 and X4, with X2 and X3 connected together.

If you connect X1 to ground, then X1 becomes "Neutral" and X4 is the source of your ground-referenced 240V SINGLE PHASE.

Please note that I am NOT a professional electrician, and I am not a licensed practicing engineer.  You should seek competent advice from a professional licensed in your jurisdiction.  High-power engineering advice, like legal advice is never completely reliable from a stranger on the internet.  Just common sense.

Huh, the way you've been talking, I thought you were a professional electrician.   Regardless of whether you are or not, isn't this the whole reason I'm required to have a permit?   They have a professional electrician go over my diagram to make sure it's sound and not going to blow up the transformer or kill someone?   I am going to study the wiring diagram again and re-read what you wrote, to see if I can understand it more clearly.   I'd connect H1 and H7 together, and then run 120VAC to H1 and H7.   I'd connect H10 and H4 together, than run the other hot from the double pole to H10 and H4.   We have 200-amp coming in.   I told my wife, we might need to upgrade that to 400-amp.   She wasn't happy about that at all, seeing how we just paid to go from 100-amp service to 200-amp service.

[Monkeh]

Forget about the transformer.

Get some P9S12As instead.

[Spork Schivago]

I cannot use the P9S13A's.   That's 208VAC outlets.   I need 220VAC+.

The HPE P9S13A shows on page 8 of the HPE G2 Switched Power Distribution Units.PDF as having input of 1-ph 200-240V 24 amps with L6-30P plug on the cord.  It has the same footprint, the same outputs as the P9S16A.  The two are probably exactly the same except for input cable, plug and internal breakers. 
There is zero chance that the P9S13A can magically reduce the input voltage of 240 down to 208 volts.
The HPE website is anything but user friendly and seems like it is a product of marketing with almost total disregard for engineering; in other words, business as usual.  The places that state it is 200-208V are most likely cut and paste errors by the person that made the document.

I gotcha.   That was the only reason we originally ruled out two P9S13A's.   The document, as you referred to, on page 8, shows that it'd work, but one their sales page, it shows it wouldn't.   When talking to their sales, it seems they tend to reference that sales page, rather than the technical document.

I think the transformer is cheaper than two P9S13A's though, and I'd like to learn how these transformers work, how to wire them properly, etc.   It's a new experience for me, so I think we're going to go that route.

[Richard Crowley]

Are all your loads (computers) set for 230V? 
Those PDU gadgets don't change the voltage.
If you put 230V in, the provide 230V out.

[Spork Schivago]

With
P9S16A
HPE G2 Swtd 7.3kVA/60309 2U INTL PDU

In the USA in a house, I see one of three things happing.

1. You burn your house down and insurance will not cover loss.
2. You get someone hurt, probably criminal charges.
3. You destroy some equipment.

HP lists four major categories of models

220-240V Input, Single Phase, International
Not a standard in USA.

200-208V Input, Single Phase, North America/Japan
Is using one phase of a three phase power source. Only industrial not in a house.

100-240V Input, Single Phase, Worldwide

This only matches the 110-120 used in USA.
And
HP makes a model for this
100-120V Input, Single Phase, North America/Japan

USA's 220-240Volt house standard does not match any of above.
As has been stated many times it is split phase with two hots and a common or center tap.

So the outlets of P9S16A with a transformer will still be non-standard in the USA and that will probably get someone/thing hurt!

C

Why would that transformer Mr. Crowley linked to get someone hurt?   When you say non-standard, do you mean not-common, or it violates some standard somewheres?   When we were looking into three-phase, an alternative the electrician gave us was a transformer, although there where some down-sides, if I remember correctly (which I might not remember correctly) about using it, compared to direct three-phase.   I think he said something about it wouldn't be "true" 3-phase.   It would look like it, but wouldn't be as clean or something.    I took it (just as a comparison) as comparing a digital oscilloscope to an analog.   The analog will provide a true sine wave, but a digital will try to emulate it, buy drawing lots of little tiny squares (or whatever) to make it appear as a sine wave.

[Bratster]

The correct thing to do in the situation is to get the correct power distribution unit. It is unfortunate that you already have one that will not work easily.

If you absolutely have to use the one that you already have, and don't mind the possibility that it may never be fully compliant since it is not intended for the u.s...

Then you have to use the Transformer that is already been picked out by other people or something along those lines.

And you would wire it for 240 volts input, split-phase, from your circuit breaker panel. And then the output would get wire for 240v with the secondary side wired as a separately derived power source. One side of the Transformer secondary would be grounded and become your neutral the other side would be 240 volts.


Also the loads you're plugging into this, they do accept 240 volts right? Stupid question but just making sure.

Edit: other people already posted some of what I said while I was typing, sorry about that.

Sent from my Moto x4 using Tapatalk

[Richard Crowley]

Because of the money we have invested in equipment at this point in time, I do not feel comfortable discussing publically what the loads are, however, if you would like to know, I would more than happy to PM you. 

We don't care what they are. I was just asking what is the nameplate rating of the power consumption.  You can't identify what kind of car I drive if I tell you that the engine has 230 horsepower.

I'm still a bit confused about the phases here.   I understand how the 240VAC works in the US.   120VAC to neutral, 120VAC to neutral, 240VAC going from hot to hot.    I understand the breaker panel, I've studied it and the various names.   I know the ground buss-bar and neutral buss-bar's are connected with a jumper wire usually.   I know there's a hot buss bar where every other connector runs off the other incoming main line.


For example, the first single pole breaker, #1, runs off the first of the two incoming main 120VAC hot lines.   #3 (directly below it), runs off the second of the two incoming main 120VAC lines.   #5 runs off the first, etc.   This is why when we install double-pole breakers, we can get 240VAC from hot to hot, instead of just 120VAC.

If I were to somehow attempt to create my own 240VAC source by using single pole breakers #1 and #2, it shouldn't provide 240VAC, from my understanding (I've never attempted), but should provide 120VAC, because they're on the same "phase".

So, if what we have is called 1-phase, but not by electrical engineers, what is it called by electrical engineers, and what is split-phase?    I thought split phase was the whole 120VAC - Neutral (or ground) - 120VAC, giving us 240VAC....

I thought split-phase was where the hot was split between two wires, each 180 degrees out of phase.   When one was at 120VAC, the other was at -120VAC, giving us 240VAC.

The standard her in North America (or at least the USA) is that the power utility delivers 240V to your house (and my house)  But it is center-tapped, and the center-tap is grounded.  So if you take either side to ground/neutral, it will be 115V.  And the only way to get 240V is to connect from one side over to the other side, but then BOTH sides will be 120V above ground because the center-tap (aka. "ground", or "protective earth" or "neutral") is grounded.

As I said before consumer, domestic appliances that run on 240V are designed with the assumption that both sides of the power line are at 120V above ground. They typically have double-pole switches, breakers, etc.  Just as a 240V branch circuit uses a DOUBLE pole breaker. 

But those HPE PDU things were designed to operate on single-phase sources.  That means that the "Neutral" side is essentially zero volts.  You don't have 240V GROUND REFERENCED coming into your house.  You have only two out-of phase 120V ground-referenced circuits.  So the only way you can get 240V is to connect from one "hot" side over to the other "hot" side.  Electricians call these "phases" but they are not.

Also, in the first post, I believe, I did mention that it was a PDU for my server rack, because I realize even the name PDU could mean multiple things, and it's important that you guys knew I was referring to a power distribution unit for a rack, holding expensive computer equipment.

You can go back and read it for yourself.  You did not identify that it was a PDU, and you did not identify that it was going into a rack, and you did not mention that it will be powering computers.  You only revealed that it was "a device".

Finally, because we are running a business, have a daughter, living in the city, etc, we will always follow the law, and get the proper permit, after drawing up our design, and have it inspected.   In the country, where we used to live, when I ran the 240VAC to my BGA rework station, we had tried, but the city inspector didn't really care about the country, which we thought was odd.   Technically, we were living in the Town of Country, not the City, but they said generally, in the country, you just wire it up or hire someone to wire it up.   They wouldn't actually come up to inspect my work.   I thought that was horrible and should have been reported.

That is good.  You can try drawing up the diagram yourself and submitting it to your jurisdiction (city or county, etc.)  But some jurisdictions won't accept submissions unless they come from a licenced architect (or whatever).  If you can befriend someone in the planning/permits office, they could help you create something they will accept.

I still want to wire the transformer myself.   I want to learn this stuff and I feel that I can do it, although I might need a little guidance.   I don't expect anyone to do my homework for me, just maybe double check my design before I take it to the city, that's what I'm hoping for.

Read the transformer specs very carefully and double-check how you are connecting.  Something that high-power really can burn down your house if you don't get it right.  You are operating in dangerous territory for an amateur.

Huh, the way you've been talking, I thought you were a professional electrician.   Regardless of whether you are or not, isn't this the whole reason I'm required to have a permit?   They have a professional electrician go over my diagram to make sure it's sound and not going to blow up the transformer or kill someone?

Yes, if it is officially approved by the jurisdiction, you have reasonable assurance that it is legal.  But there are many details where you could go wrong that are not on the plans or reviewed by the authorities.

I am going to study the wiring diagram again and re-read what you wrote, to see if I can understand it more clearly.   I'd connect H1 and H7 together, and then run 120VAC to H1 and H7.   I'd connect H10 and H4 together, than run the other hot from the double pole to H10 and H4.   We have 200-amp coming in.   I told my wife, we might need to upgrade that to 400-amp.   She wasn't happy about that at all, seeing how we just paid to go from 100-amp service to 200-amp service.

NO!  Nobody mentioned 120VAC anywhere.  The transformer will take the split-phase 240V from your domestic service and turn it into 240V "single-phase", ground-referenced which is what the HPE PDU is designed for.  If you try to connect that transformer to a 120V circuit, you will be lucky if only the breaker blows.

[IanB]

They have a professional electrician go over my diagram to make sure it's sound and not going to blow up the transformer or kill someone?

Just for clarity, there's a difference between an electrician and an engineer (a P.E.).

An electrician will provide and/or inspect an installation to make sure it complies with the applicable code. You may get some variation between electricians about how to interpret the code in some areas of detail, but primarily electricians follow their training and make sure what is done matches what the code says should be done.

On the other hand, the code itself is written by P.E.'s with relevant professional experience in wiring and power distribution systems. If you hire a professional engineer they can potentially design a system that has variances from the code, and can justify by calculation why those variances are safe, and can put their professional stamp on that design to certify it. Needless to say, it will cost a lot more to hire a P.E. than to hire an electrician. But in special circumstances it may be worth it.

(This is just in general--I'm not saying you need to hire a P.E.)

[bob225]

I would check your lease or land title and the zoning laws in you area, the last thing you need is $K in fines, or swat busting your door down because they think you have a grow (high power usage)


2018 Honey I blew up the house

[Richard Crowley]

Why would that transformer Mr. Crowley linked to get someone hurt? 

Easy.  By improper installation, incorrect connection, etc.  It is unfortunate when somebody powers a little 5V board from 12V and turns it into toast.  But is is a whole different ballgame when you are talking about thousands of watts of power that could kill your whole family AND burn down your house.

When you say non-standard, do you mean not-common, or it violates some standard somewheres?

Didn't you answer that yourself when you said that the electrician would not connect to the IEC Euro-connector?  Of course, maybe that was just someone who does domestic wiring in private homes.  Not surprising that they would shy away from an unfamiliar connector.  But if you were talking to an electrical contractor that does big commercial and industrial projects, they may have had a very different response.

When we were looking into three-phase, an alternative the electrician gave us was a transformer, although there where some down-sides, if I remember correctly (which I might not remember correctly) about using it, compared to direct three-phase.   I think he said something about it wouldn't be "true" 3-phase.   It would look like it, but wouldn't be as clean or something.    I took it (just as a comparison) as comparing a digital oscilloscope to an analog.   The analog will provide a true sine wave, but a digital will try to emulate it, buy drawing lots of little tiny squares (or whatever) to make it appear as a sine wave.

Yes, people who buy big industrial machines (lathes, milling machines, etc.) to put in their garage are faced with the problem that big motors operate on 3-phase power which is very rare here in North America in private homes.  So there are all sorts of gadgets from rotary converters (a single-phase motor driving a 3-phase alternator), or electronic circuits that create 3-phase, to dodgy resonant contraptions that put out pseudo-3-phase.

But you do not need 3-phase.  You are having enough problems just getting 240V single-phase.  And the PDU you selected isn't suitable for a 3-phase source any more than it is suitable for 240V split-phase.

[Spork Schivago]

Are all your loads (computers) set for 230V? 
Those PDU gadgets don't change the voltage.
If you put 230V in, the provide 230V out.

Yes.   For the servers, the PSUs we needed are only provided in 240V, because of how large they are.   For the other equipment, we have the option of running 120VAC or 240VAC.    For the PSUs, the lowest I think was 220VAC, not 208VAC or anything.

The ones for the servers run optimal when the hardware is drawing 80% of what they're rated for.   Each server has two 1400 watt PSUs in them.   It's probably obvious that we have a switch, so I see no harm in sharing that.   The switch has two 500 watt PSUs, currently running at 120VAC.   The second is for redundancy.    With the various hardware, there's proper ways to make sure they're cooled adequately.   For example, with our servers, we needed to purchase the high performance fan kits and heat sinks, because of how much more powerful the CPUs where compared to the ones that came with them.   The idea is to switch all the equipment that is capable of running off 120VAC or 240VAC over to 240VAC.

I can PM you a list of the other equipment that draws a good bit of current, if you're interested.   I just don't want to share it publicly on the list.   We have a lot of thieves around here.   I had some acquaintances that weren't the best type of crowd.   We are dealing with what we consider confidential / sensitive information, and with some of the contracts we have, we need to take certain security precautions.   We have x amount of time to implement the SOPs and then they come to the house and perform an audit.   It's our responsibility to keep the information secure, the network secure, etc.   We can't even have anyone down in the basement unless they sign an NDA.

For the local electric company, we had to have them install something outside the house, so they didn't have to go down in the basement to read the meter.

[IanB]

As for the cooling, eventually we will get central air, but right now, being in the basement, we've kinda got lucky.   Throughout the year, it seems to maintain an almost stable temperature and is cool.

Hopefully you realize that will only be true as long as the basement is not full of computer equipment?

At work our server rooms always have to have big powerful aircon units in them. If for any reason the aircon unit fails the temperature in the room skyrockets, alarms go off, and then all the equipment shuts down due to overheating.

What you need to do, if you haven't already done it, is to add up the power consumption of all the equipment in the basement (seems like it could be around 7 kW based on the size of the PDU?), and then determine how you are going to remove 7 kW of heating from the room. You can imagine that if you put a 7 kW electric heater in your basement it is not likely to maintain a stable, cool temperature...

[Spork Schivago]

...

I am going to study the wiring diagram again and re-read what you wrote, to see if I can understand it more clearly.   I'd connect H1 and H7 together, and then run 120VAC to H1 and H7.   I'd connect H10 and H4 together, than run the other hot from the double pole to H10 and H4.   We have 200-amp coming in.   I told my wife, we might need to upgrade that to 400-amp.   She wasn't happy about that at all, seeing how we just paid to go from 100-amp service to 200-amp service.

NO!  Nobody mentioned 120VAC anywhere.  The transformer will take the split-phase 240V from your domestic service and turn it into 240V "single-phase", ground-referenced which is what the HPE PDU is designed for.  If you try to connect that transformer to a 120V circuit, you will be lucky if only the breaker blows.

It was the 2nd and 3rd post I made where I said it was a PDU going into a rack and gave the model number, you are correct.   I actually tried uploading pics of the plug and in that post, I believe I actually wrote a statement saying that because PDU can mean multiple things, blah, blah, blah, this was for a rack and would run computer equipment.   But for some reason, that post never made it threw.

So, I run both "phases" or "mains" into H1 and H7, after tying them together?    and then neutral into H10 and H4 together?    My wife just got home and I'm the only one who watches my daughter while she's at work, so I can't do much with the business until she gets home.   I can post a list of exactly what loads we have (or at least, what power supplies we have).

I think C said there's no way to safely do this though.   So if the transformer is wired correctly, I'm a bit confused as to why some say it will work, some say it won't.   We have also sent a message to our licensed electrician, but that's a pain now.   We were offered some contracts, they're a one time thing.   It's not what we want to do with our business, but we took them.   We know someone who knows someone and a company or two outsourced to us.   Having someone down there, even to wire it up means we gotta get it approved by at least one of the companies, if not both, have the electrician sign an NDA, etc.   It becomes a real pain.   In my jurisdiction, I can provide the sketch myself.   We did that when we wired the low-voltage wires for our daughter's room, so we're familiar with the process there.    Here, we can run ethernet, for example, between two floor joists that connect to the cold-air return, but only if we use plenum grade ethernet.  We don't actually run it down the ductwork, we run it outside of the duct-work.   But if it wasn't plenum grade, we wouldn't be able to do that, unless we used conduit or something along those lines.

[Spork Schivago]

Why would that transformer Mr. Crowley linked to get someone hurt? 

Easy.  By improper installation, incorrect connection, etc.  It is unfortunate when somebody powers a little 5V board from 12V and turns it into toast.  But is is a whole different ballgame when you are talking about thousands of watts of power that could kill your whole family AND burn down your house.

Yes, I understand that, but _if_ it's wired correctly, the way C was responding, it sounded like it was just wrong and wouldn't work.   Even DC can be dangerous and kill you.    I try to treat all electricity as the same.   I don't have special rules just for low-voltage sources.   I try to practice safe standards everywhere, even if there isn't necessarily a threat or chance for personal injury.   That way, it becomes a bit of muscle memory.

When you say non-standard, do you mean not-common, or it violates some standard somewheres?

Didn't you answer that yourself when you said that the electrician would not connect to the IEC Euro-connector?  Of course, maybe that was just someone who does domestic wiring in private homes.  Not surprising that they would shy away from an unfamiliar connector.  But if you were talking to an electrical contractor that does big commercial and industrial projects, they may have had a very different response.

When we were looking into three-phase, an alternative the electrician gave us was a transformer, although there where some down-sides, if I remember correctly (which I might not remember correctly) about using it, compared to direct three-phase.   I think he said something about it wouldn't be "true" 3-phase.   It would look like it, but wouldn't be as clean or something.    I took it (just as a comparison) as comparing a digital oscilloscope to an analog.   The analog will provide a true sine wave, but a digital will try to emulate it, buy drawing lots of little tiny squares (or whatever) to make it appear as a sine wave.

Yes, people who buy big industrial machines (lathes, milling machines, etc.) to put in their garage are faced with the problem that big motors operate on 3-phase power which is very rare here in North America in private homes.  So there are all sorts of gadgets from rotary converters (a single-phase motor driving a 3-phase alternator), or electronic circuits that create 3-phase, to dodgy resonant contraptions that put out pseudo-3-phase.

But you do not need 3-phase.  You are having enough problems just getting 240V single-phase.  And the PDU you selected isn't suitable for a 3-phase source any more than it is suitable for 240V split-phase.

Yes, I know I don't need three-phase.   We made the choice for 1-phase because of costs.   I was using that just as an example.  I was thinking maybe what C meant was with the transformer, it wouldn't be considered true 1-phase 240VAC.    It'd be pseudo-1-phase 240VAC and would possibly not be safe, for example, with the devices that are US made with the 120VAC / 240VAC switch on the PSUs, or with the actual PDU itself.   Do you follow what I was saying now?

Thanks.

[Spork Schivago]

As for the cooling, eventually we will get central air, but right now, being in the basement, we've kinda got lucky.   Throughout the year, it seems to maintain an almost stable temperature and is cool.

Hopefully you realize that will only be true as long as the basement is not full of computer equipment?

At work our server rooms always have to have big powerful aircon units in them. If for any reason the aircon unit fails the temperature in the room skyrockets, alarms go off, and then all the equipment shuts down due to overheating.

What you need to do, if you haven't already done it, is to add up the power consumption of all the equipment in the basement (seems like it could be around 7 kW based on the size of the PDU?), and then determine how you are going to remove 7 kW of heating from the room. You can imagine that if you put a 7 kW electric heater in your basement it is not likely to maintain a stable, cool temperature...

Yes, we know that it will heat up quickly when we start powering the equipment up, and have plans for a central air conditioning unit.   Until then, we have A) a portable unit we can use B) a wall unit we can use.   They're not the best options, but they can work until we have the central AC installed.

We did add up all the equipment and currently got around 5kW, but that was excluding the upgrades that we are planning on purchasing.   With the extra's, yes, we'll be around 7 kW, then during phase three, we'll be even higher, and will need another PDU.    At that point, hopefully we have enough income to get a dedicated panel just for the business though.

Removing 7 kW of heating is something I hadn't put too much thought into.   I didn't think of it like that, so I like that idea.   We remove the condensation from the room, which makes it feel cooler and doesn't provide danger to the equipment (condensation tends to rust equipment, might even short parts out, etc).    We do need to have the outside of our house tore up and properly sealed, but that's later on.

We have special sensors to monitor the temperature of the equipment in the rack, and it's designed to send us various messages, set off alarms, if certain conditions are met.    One of them includes heat.   If heat gets too high, we get cell phone messages, and there's a program written that should set off one of the alarm systems down there.

At my old work, in the server room, they had residential ACs running and just dumping the water between the cement walls, which was a horrible idea, but it saved them money.   Eventually, this caused a lot of problems for the company with things like mold.   So in the end, it costed them more money than they saved.

We also plan on purchasing a whole-home generator, that will be installed by a professional, with an automatic transfer switch, and we still need to figure out the UPS setup, where it can power the equipment long enough for the whole-home generator to kick on.   That's one of the biggest reasons we took on the first contract.   It's getting close to being finished and pays us a good amount of money that should allow us to finish purchasing those things I just mentioned.

[Spork Schivago]

Right now, we're currently at 6,360 watts, assuming full load on all devices.   That's what all the name plates, added up, come to.   Keep in mind, most systems shouldn't be running at exactly what the power supply is rated for.   They should be running at around 80% or so of what the power supplies are rated for.

Almost all the devices don't have a switch for 240VAC, but they say 115 to 230VAC for input.   And reading the technical manuals, they auto-detect and expect single-phase.

There are some other devices that we're using, but they're not rack-mountable, so we did not include them, like the BGA rework station that claims it draws 4,800 watts.   It's using Elstien heating elements for the pre-heater part, but it's a cheap Scotle unit.   Just something we bought a few years back to get us up and running.   They're not powered by this PDU, but are connected to the same panel as the PDU's transformer will be connected to.

I think I will go for the 10kVA one.   

[james_s]

Remind me what this is all for?

IMO by the time you get to several kW of computer gear in the basement, it's time to start looking for a proper data center.

[C]

Looks like you like to ignore simple facts.

In the USA the standard electrical outlet is 110-120 volts 60hz.

All 220-240 volt stuff uses different connectors. Because of the difference people take more care.

Think of how many people in the USA have used computer power cords. For the USA the end that connects to a computer is 115volts. For a lot of the world that is 220volts but not in USA.

So now you have people seeing the computer end thinking 115volts and connecting an extension cord to your PDU, but that is not 115 volts. A part of safe is knowing what to expect.
So what is a safe European standard is not as safe in the USA due to common thought.

The added transformer is creating a safe NON-USA standard in addition to wasting power. That transformer will get hot, and that is a waste of power. 

One thing you might like to know is that 220 volt 60hz is more dangerous then 220 volt 50hz. The 60hz has a greater chance of messing up your heart beat then 50hz.

If you want real safe 220 volts using a USA split phase( 220 Volts with a neutral center tap) you use a four wire connection. The forth connection the safety ground.
Unlike the rest of the world USA 220 volt equipment often has some 115 volt loads.

C

[Richard Crowley]

So, I run both "phases" or "mains" into H1 and H7, after tying them together?   

No. If you "tie both phases together" you will put a dead short across your utility mains power and instantly trip the breaker. 
Hopefully the breaker will protect you before starting a fire and burning down your house.

and then neutral into H10 and H4 together?

No. The neutral plays no part here.  You only need the neutral line if you want 120V.

The only way you can get 240 volts to feed into the transformer is between the two "phases".
One "phase" goes to H1-H7, and the other "phase" goes to H4-H10

Neutral goes to X1 and X4 is your single-phase 240V to feed your PDU.

[Richard Crowley]

So now you have people seeing the computer end thinking 115volts and connecting an extension cord to your PDU, but that is not 115 volts. A part of safe is knowing what to expect.

Yes the IEC 60320 power connector (the standard connector on computers, printers, etc.) is ambiguous because it is used for both 120V and for 240V connections.  The only protection here is that the HPE PDU is a specialty product in a special environment where only people who know better will be plugging things into it.

The added transformer is creating a safe NON-USA standard in addition to wasting power. That transformer will get hot, and that is a waste of power. 

Yes. Alas that is true whenever you must convert power from one voltage to another.

One thing you might like to know is that 220 volt 60hz is more dangerous then 220 volt 50hz. The 60hz has a greater chance of messing up your heart beat then 50hz.

I would like to see some reference for that.  It doesn't make sense from other evidence.

If you want real safe 220 volts using a USA split phase( 220 Volts with a neutral center tap) you use a four wire connection. The forth connection the safety ground. Unlike the rest of the world USA 220 volt equipment often has some 115 volt loads.

The modern standard for North America ALWAYS requires a safety ground (BrEnglish: "protective earth") connection.  THe modern convention is a green wire with yellow stripe.

The presence of the safety ground does NOT make a product like that HPE PDU "safe".  Because the PDU was designed with the assumption that Neutral is essentially zero volts.  Connecting it to USA split phase will put Neutral at 120V which is unsafe for this PDU.  The presence of the safety ground does not change this problem.

[tpowell1830]

Patience is often referred to as a virtue... if so then Mr. Crowley is very virtuous.

 

[Spork Schivago]

Remind me what this is all for?

IMO by the time you get to several kW of computer gear in the basement, it's time to start looking for a proper data center.

This is a datacenter.   Our datacenter.   We are just running it out of the house for now, instead of renting a building in a commercial zone.   We've already okay-ed it with the city, before we purchased the house.   We can have a sign in the window, but can't put a big sign outside, other than that, we're good.

We used to rent a few servers over the internet, but that got to the point where it was no longer cost effective.

[james_s]

That's surprising with the trends these days, even medium sized companies are outsourcing their server needs to cloud based suppliers. One of the places I worked years ago we had our own servers but leased a rack at a collocation center a few blocks away. They provided the power, cooling and data, we racked and maintained our hardware. 

[Spork Schivago]

Looks like you like to ignore simple facts.

In the USA the standard electrical outlet is 110-120 volts 60hz.

All 220-240 volt stuff uses different connectors. Because of the difference people take more care.

Think of how many people in the USA have used computer power cords. For the USA the end that connects to a computer is 115volts. For a lot of the world that is 220volts but not in USA.

So now you have people seeing the computer end thinking 115volts and connecting an extension cord to your PDU, but that is not 115 volts. A part of safe is knowing what to expect.
So what is a safe European standard is not as safe in the USA due to common thought.

The added transformer is creating a safe NON-USA standard in addition to wasting power. That transformer will get hot, and that is a waste of power. 

One thing you might like to know is that 220 volt 60hz is more dangerous then 220 volt 50hz. The 60hz has a greater chance of messing up your heart beat then 50hz.

If you want real safe 220 volts using a USA split phase( 220 Volts with a neutral center tap) you use a four wire connection. The forth connection the safety ground.
Unlike the rest of the world USA 220 volt equipment often has some 115 volt loads.

C

We need 240VAC, again, for the server, not 220VAC, although it would run on 220VAC.   Most of our equipment is NOT from the USA.   The cords to power these devices are NOT what you find with a NORMAL USA bought PC, so I highly doubt anyone who is allowed to be around the rack will try plugging anything into the PDU.    I mean, simple fact, strangers aren't going to be down here, and if they are, they're breaking the law.   Eventually, we have to worry about my daughter, but that's a long ways away, and even then, she cannot physically get into the rack to plug anything into the PDU.   Ohm's law shows us if we double the volts, we cut the current draw in half.   200v * 2 amp = 400 watts.   20 amp * 20v = 400 watts.    I think I'd rather get shocked, if I had to get shocked, at the 200v, 2 amp, rather than the 20 amp.

I have no idea how anyone is going to plug any cords into the PDU, I don't know what you think the inputs look like, but you physically cannot take a normal PC cord and plug it into the PDU.   You need special cords....most of our energy hungry equipment is designed to run off 240VAC, but most of it can go down to 100VAC.   I mean, we have some American made workstations, but they're not going into the rack at all, and aren't being powered by this PDU.   A lot of stuff came from Germany.   There's usually no switch on these pieces of equipment to flip.   They say 100VAC - 240VAC.

I mentioned in a previous post that security was our responsibility and we get audited, where some people from some companies come in and check to make sure everything is up to their standard.   We get a report on what needs to change, if anything, and it's our responsibility to change what they list.   Once we wire up the 15kVA transformer (or higher someone to wire it up for us), we'll have to have yet another one of those pesky audits.

There's security in place.  Maybe you can take comfort in knowing that currently, no one who is specifically supposed allowed in the datacenter can get into the datacenter without doing a lot of illegal work?   This isn't a playroom.   The idea is though, we do our own thing once these contracts are up, and hopefully, later on in life, our daughter takes interest.   If not, that's okay, we'll love and accept her no matter what.   That's years down the road before we burn that bridge though.

Heck, do you know how hard it was to say no to the three phase installation?   We were talking over 50,000$ and almost went for it, because then we can purchase stuff that's a bit more suited to our task at hand.   I feel better having a PDU hooked up with a backup sitting on the shelf in case one shits the bed, rather than daisy chaining a whole bunch to try and get my systems running.

[Spork Schivago]

That's surprising with the trends these days, even medium sized companies are outsourcing their server needs to cloud based suppliers. One of the places I worked years ago we had our own servers but leased a rack at a collocation center a few blocks away. They provided the power, cooling and data, we racked and maintained our hardware.

We got something similar going here.   One of the companies we can see from our house, but they're really big.   They try to use resources in the community, and have helped my city a lot.   Here, we outsource to Microsoft for some of our needs.   We use a CSP license and have Enterprise E3 editions running.   Our exchange server is on a Microsoft server, our active directory is on a Microsoft server.   Heck, even our conference calls go through Microsoft!   However, there's stuff we have to make sure doesn't get uploaded to the Microsoft server or any of our VPSes.   Stuff that has to stay local.   We have a fancy switch for that, that has routing capabilities and we segregate / isolate different networks, some with access to the outside world, some without.   That way, we keep the residential stuff on the residential side, the business machines that are supposed to have internet access can reach our gateway, and the machines that are not supposed to, cannot.   It was a real pain to setup originally.   I've always been a Cisco man and configuring a Cisco switch is a lot different than configuring an HPE switch.   Lot of new info to learn and little bits of sleep, but we're slowing down now.   Slowly getting there.   I'd say the main contract, I wouldn't have it if it wasn't for some connections I have to have either worked at the company or currently working at the company.   Kinda got lucky there.

One thing, it seems, people keep forgetting, our servers.   We had two options.   3-phase, or 1-phase 240VAC.   I think it was Mr. Crowley who pointed out that PDUs only push out what they're fed in.   You feed them 240VAC split-phase, they put out 240VAC split-phase.   You feed them 240VAC 1-phase, they put out 240VAC 1-phase.    So I'm wondering how the people who keep recommending the 120VAC - 0 - 120VAC solutions have come up with a way of powering the servers.   I think we'd be back to an unsafe environment to the same unsafe environment we'd be in now if we ran 120VAC and 120VAC to our PDU.

[Spork Schivago]

I stand corrected.   These power supplies are the only option for our servers.   There are no three-phase ones like I was thinking.   They only make the 1400 watt in one style that's compatible with our servers.

[Richard Crowley]

Note that "120VAC - 0 - 120VAC" is the same thing as "split-phase".

None of the HPE PDU are designed to handle split-phase.  They are all designed for schemes where Neutral = Ground.

If you connect any of those HPE PDU things to domestic split-phase where Neutral = 120VAC, you are setting up a situation that is dangerous for both equipment and people.

That is why a transformer is need to convert 120-0-120 ("split-phase")  into 240-0 ("single-phase")

[Bratster]

Looks like you like to ignore simple facts.

In the USA the standard electrical outlet is 110-120 volts 60hz.

All 220-240 volt stuff uses different connectors. Because of the difference people take more care.

Think of how many people in the USA have used computer power cords. For the USA the end that connects to a computer is 115volts. For a lot of the world that is 220volts but not in USA.

So now you have people seeing the computer end thinking 115volts and connecting an extension cord to your PDU, but that is not 115 volts. A part of safe is knowing what to expect.
So what is a safe European standard is not as safe in the USA due to common thought.

The added transformer is creating a safe NON-USA standard in addition to wasting power. That transformer will get hot, and that is a waste of power. 

One thing you might like to know is that 220 volt 60hz is more dangerous then 220 volt 50hz. The 60hz has a greater chance of messing up your heart beat then 50hz.

If you want real safe 220 volts using a USA split phase( 220 Volts with a neutral center tap) you use a four wire connection. The forth connection the safety ground.
Unlike the rest of the world USA 220 volt equipment often has some 115 volt loads.

C

We need 240VAC, again, for the server, not 220VAC, although it would run on 220VAC.   Most of our equipment is NOT from the USA.   The cords to power these devices are NOT what you find with a NORMAL USA bought PC, so I highly doubt anyone who is allowed to be around the rack will try plugging anything into the PDU.    I mean, simple fact, strangers aren't going to be down here, and if they are, they're breaking the law.   Eventually, we have to worry about my daughter, but that's a long ways away, and even then, she cannot physically get into the rack to plug anything into the PDU.   Ohm's law shows us if we double the volts, we cut the current draw in half.   200v * 2 amp = 400 watts.   20 amp * 20v = 400 watts.    I think I'd rather get shocked, if I had to get shocked, at the 200v, 2 amp, rather than the 20 amp.

I have no idea how anyone is going to plug any cords into the PDU, I don't know what you think the inputs look like, but you physically cannot take a normal PC cord and plug it into the PDU.   You need special cords....most of our energy hungry equipment is designed to run off 240VAC, but most of it can go down to 100VAC.   I mean, we have some American made workstations, but they're not going into the rack at all, and aren't being powered by this PDU.   A lot of stuff came from Germany.   There's usually no switch on these pieces of equipment to flip.   They say 100VAC - 240VAC.

I mentioned in a previous post that security was our responsibility and we get audited, where some people from some companies come in and check to make sure everything is up to their standard.   We get a report on what needs to change, if anything, and it's our responsibility to change what they list.   Once we wire up the 15kVA transformer (or higher someone to wire it up for us), we'll have to have yet another one of those pesky audits.

There's security in place.  Maybe you can take comfort in knowing that currently, no one who is specifically supposed allowed in the datacenter can get into the datacenter without doing a lot of illegal work?   This isn't a playroom.   The idea is though, we do our own thing once these contracts are up, and hopefully, later on in life, our daughter takes interest.   If not, that's okay, we'll love and accept her no matter what.   That's years down the road before we burn that bridge though.

Heck, do you know how hard it was to say no to the three phase installation?   We were talking over 50,000$ and almost went for it, because then we can purchase stuff that's a bit more suited to our task at hand.   I feel better having a PDU hooked up with a backup sitting on the shelf in case one shits the bed, rather than daisy chaining a whole bunch to try and get my systems running.

220 230 and 240 volts are all the same.
Voltage wise all of those are acceptable. *

Same thing with 110 115 and 120, all of them acceptable.

In the US the nominal is 120 and 240, but it's quite common for people to say 110 and 220 Etc.

I'm not familiar with the UK at all, but I think their nominal voltage is 230 volts? But the specification allows anywhere from 220 to 240 or something like that.

*Except in some special cases, mainly on large equipment that has its own transformer built-in, then there are multiple Taps to get the voltage just right.



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[Bratster]

IMHO while I think you could install this with minimal problems you really should get an electrical engineer or commercial electrician that is familiar with something along these lines to have a plan drawn up and run it past your electrical inspector for the city and make sure everything will be okay.

You seem very concerned with security and Audits and having it done as right as it can be and all of that stuff;
 so having this planned out by a professional and approved by the inspector before you start doing things would be highly important. IMO

I would bet your insurance is going to absolutely require that.



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[Bratster]

Here is a really crappy back of the napkin bare basic sketch of what you need and has already been suggested by one or two other people in here.

It is missing probably a circuit breaker on the output of the Transformer and is not detailed, but that shows you how the Transformer would get wired up.

Your house power comes in on the left with two 120volt lines that have 240 volts between them, off of a 2 gang breaker, that feeds the Transformer.

The output of the Transformer is now its own isolated power source, so you are now able to call one side of it line at 240 volts and the other side of it neutral at 0 volts and can add a neutral to ground bond in a new breaker panel.


WARNING:
I'm not a professional engineer, I have no certifications, I have warned you to get a professional, this drawing may kill you and burn your house down.



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[Teledog]

At the risk of p*ssing some people off,
Kitchen outlets/receptacles, if done to most American codes, have alternating hot lines, above & below on each outlet (hence the center breakaway tab on the receptacle line connections)
No, this wont run a full 32 amps (do you really require that much current?)
Want easy? One can purchase these units for North American 220 (240?);
https://www.quick220.com
I've made my own ..for an Australian wired vertical donair rotisserie - works very well! 
Do not use/connect the neutral(s), just use the two hots (upper and lower receptacle)- one to each side of the 220/240 box outlet, and the ground(s), of course.
Test your outlets/receptacles with a meter before trying! Not every electrician follows code.
Perhaps do the same technique with higher UL current rated connections?
G'luck!

[Richard Crowley]

Kitchen outlets/receptacles, if done to most American codes, have alternating hot lines, above & below on each outlet (hence the center breakaway tab on the receptacle line connections)

Can you cite an authoritative reference for that?
In 70 years I have never seen (or even heard of) such an extraordinary thing.

Even if it is everything as claimed, while it might be suitable for some random domestic applications, it is certainly not up to the task of operating a rack full of heavy-duty servers.  Not if reliability means anything to you.

[Gregg]

Mr. Crowley certainly has more patience than I. 
When stated that

“None of the HPE PDU are designed to handle split-phase.  They are all designed for schemes where Neutral = Ground.”

I believe He may have overlooked the P9S13A, as I previously posted, states it is for North America and Japan as it is rated for 200 -240V, uses a standard L6-30P plug (208-240V 3 pole twist lock labeled L1, L2 and Ground in the USA) and it has 2ea 2pole 20a breakers, one for each level of the PDU.  It also has the exact same receptacles as the one chosen by Spork. 
I’m not trying to rag on Mr. Crowley here, but I still think two of the P9S13A deserve more consideration especially since Spork has stated that he may expand his power requirements.  It would eliminate the need for a transformer unless his servers specifically need a grounded neutral which is very doubtful for SMPS typical server power supplies. 
Bratster’s drawing is a fine example of how to install a transformer; with the breaker panel on the output and proper breakers installed I believe it would pass any reasonable inspection.  However there are inspectors out there that kind of make up their own rules.

[Richard Crowley]

Certainly Spork would be better off with something he can connect directly to his split-phase domestic service as @Gregg observes.  It seems unfortunate that he selected that particular PDU.  The "documentation" provided by HPE leaves a great deal to the imagination from lack of useful details.

[Gregg]

Kitchen outlets/receptacles, if done to most American codes, have alternating hot lines, above & below on each outlet (hence the center breakaway tab on the receptacle line connections)

Can you cite an authoritative reference for that?
In 70 years I have never seen (or even heard of) such an extraordinary thing.

Even if it is everything as claimed, while it might be suitable for some random domestic applications, it is certainly not up to the task of operating a rack full of heavy-duty servers.  Not if reliability means anything to you.

NEC article 210.4 allows the use of two circuits to the same receptacle and even allows sharing the return.  Enclosed is s can from the 2005 NEC handbook

I suggest that Spork buy an older copy of the NEC handbook on ebay, study it and keep it for future reference.  They don't change much between editions so a 2005 (big yellow book) or a 2008 (big blue book) or a 2011 (big red book) by the NFPA National Fire Protection Association (not by anyone else) will probably suffice

[Gregg]

Here is an example of a proper PDU being installed.  Input is 480V 3ph from one of two redundant 400KVA UPS units backed up by two redundant utility services and two 2MW V16 Caterpillar generators. Output is two panels of 42 breakers and 225a 208/120V input each.  The branch wires go through small current transformers near each breaker.  There are two grounds, the green and yellow is isolated all the way back to the data center’s ground ring; the green are tied to the PDU chassis, transformer neutral and back to the UPS ground, which in turn eventually goes back to the main ground ring. 
Data centers are very complicated in order to attempt zero down time.

[C]

One thing

When you buy computer equipment in the USA and it states that is it 220-240 Volt. There is a good chance that it is built for the USA standards.
With most businesses having 220-240 split phase power, would be a huge loss of sales not to support this.

Very easy for a computer company to make a computer power supply that works with standard 220-240 split phase power source.

C

[Monkeh]

One thing

When you buy computer equipment in the USA and it states that is it 220-240 Volt. There is a good chance that it is built for the USA standards.
With most businesses having 220-240 split phase power, would be a huge loss of sales not to support this.

Very easy for a computer company to make a computer power supply that works with standard 220-240 split phase power source.

C

End devices like that generally do not care anyway.

None of my power supplies would have the slightest problem running on split phase nor be a danger.

[Richard Crowley]

End devices like that generally do not care anyway.
None of my power supplies would have the slightest problem running on split phase nor be a danger.

Yes that is all true.  But the issue here is the power controller/strip "PDU" , not the destination loads (which probably don't care as you say).

If the PDU controls/switches/protects only the "Line" (hot) side and you connect the "Neutral" (low) side to 120V (because of using 120-0-120 "split-phase") then you have live, active 120V on the "Neutral" side of all the outlets even when the PDU is supposed to be switched off (or has tripped the breaker because of a fault).
And if the fault was on the "Neutral" side, it may have no protection at all because it was designed with the assumption the Neutral = Ground.

"Split-phase" 120-0-120 is a bastard scheme if you need 240V for any kind of proper industrial gear (including these HPE PDU things)
Industrial gear is designed for proper single-phase (240-0)

[Monkeh]

End devices like that generally do not care anyway.
None of my power supplies would have the slightest problem running on split phase nor be a danger.

Yes that is all true.  But the issue here is the power controller/strip "PDU" , not the destination loads (which probably don't care as you say).

I'm well aware, and in fact have been in this thread making these points..

[C]

"Split-phase" 120-0-120 is a bastard scheme if you need 240V for any kind of proper industrial gear (including these HPE PDU things)
Industrial gear is designed for proper single-phase (240-0)

Actually Split-phase can be safer.

First you have GFCI or RCD to think about.
To reduce EMI or RFI X-cap's or Y-cap's are used. With two wire power and one side Neutral you are connecting 1/2 AC voltage to somethiing, the Neutral lead or safety ground. To work around this the GFCI or RCD has to be made less sensitive. With the center Neutral you have 0 volt AC EMI/RFI connected to Neutral so a more sensitive GFCI/RCD is possible..

There is no perfect wire so there is always a voltage drop on the Neutral lead making it NOT ground. A short from Neutral to something is connecting the voltage drop to something and not detected with fuse or circuit breaker in the hot lead. With split-phase this is detected. Shorts like this do happen and can have many watts of power turned in to heat.

Then you have 1/2 voltage difference to actual ground, again safer

The big cost is often just the one added wire and dual breakers.

Equipment designed for split-phase can be designed three ways.

1. You have Equipment that needs some 110-120 for internal use in addition to 220-240. Here three wire or safer 4 wire connection.

2. like above but with no 110-120 internal use so that the Neutral lead supplies no power.

3. A variation of #2 is Two hots and where Neutral lead is just used for a safety ground.

Three phase is just a shift to three hots vs two hots.

C

[Richard Crowley]

Actually Split-phase can be safer.

Yes, that all may be true, but none of it is beneficial (or even relevant) to the specific case at hand.
Bottom line: The PDU appears to be designed to have Neutral = ground and connecting split-phase to it is dangerous.

[Gregg]

Actually Split-phase can be safer.

First you have GFCI or RCD to think about.
To reduce EMI or RFI X-cap's or Y-cap's are used. With two wire power and one side Neutral you are connecting 1/2 AC voltage to somethiing, the Neutral lead or safety ground. To work around this the GFCI or RCD has to be made less sensitive. With the center Neutral you have 0 volt AC EMI/RFI connected to Neutral so a more sensitive GFCI/RCD is possible..

There is no perfect wire so there is always a voltage drop on the Neutral lead making it NOT ground. A short from Neutral to something is connecting the voltage drop to something and not detected with fuse or circuit breaker in the hot lead. With split-phase this is detected. Shorts like this do happen and can have many watts of power turned in to heat.

Then you have 1/2 voltage difference to actual ground, again safer

The big cost is often just the one added wire and dual breakers.

Equipment designed for split-phase can be designed three ways.

1. You have Equipment that needs some 110-120 for internal use in addition to 220-240. Here three wire or safer 4 wire connection.

2. like above but with no 110-120 internal use so that the Neutral lead supplies no power.

3. A variation of #2 is Two hots and where Neutral lead is just used for a safety ground.

Three phase is just a shift to three hots vs two hots.

C

Three phase is far from just a shift to three hot leads.  There are several methods of connection used in the US, but all of the large data centers I have worked with use 480 volt 3ph UPSs connected to 208/120V transformers and then breaker panels.  Several customers had large cabinets that had 40 amp 208V 3ph power supplied.  3ph when rectified has far less ripple than single phase and the 3ph SMPS are more efficient.   

Neutral conductors should never be used as ground connectors.  True, there are a few cases where the NEC allows a ground conductor to carry a small neutral current; but I would never wire my house in such a manner, even if it is officially OK. 

Back to the subject at hand; Richard Crowley is absolutely correct and it is sad that Spork purchased the wrong PDU.  It isn’t our fault he didn’t ask first and now there isn’t any way to easily fix the situation short of taking it apart and seeing if it can be modified to install 2 pole breakers and to ensure the switching mechanism switches both hot legs of the 240V. 

If I were in Spork’s shoes, I would try to return the PDU on the grounds that they didn’t properly describe it in their literature and instead purchase two of the P9S13A units if he needs the capability to switch each branch circuit remotely. 

Let’s consider the possible unsafe modes of failure using the P9S16A PDU:

Suppose there is an internal ground fault in one of the server power supplies that is from the hot without the single pole breaker.  The single pole breaker doesn’t respond and the fault remains until the 40 amp two pole breaker trips after things catch fire.  Or the fault gets to the point where it blows up the power supply and possibly ruining the whole server.  If the 40 amp breaker trips, and nothing much else happens your whole system still goes down until you figure out the problem.  Assuming your server racks/cabinets are properly grounded; if they are not, you could be in for the shock of your life.

Suppose you figure out there is something wonky with one of the server power supplies and you turn it off remotely because you are not at home; but the PDU switch only turns off one hot leg.  Failure modes are the same as above.

I’m sure others on the forum could add to this list.

[james_s]

Same thing with 110 115 and 120, all of them acceptable.

In the US the nominal is 120 and 240, but it's quite common for people to say 110 and 220 Etc.

I'm not familiar with the UK at all, but I think their nominal voltage is 230 volts? But the specification allows anywhere from 220 to 240 or something like that.

*Except in some special cases, mainly on large equipment that has its own transformer built-in, then there are multiple Taps to get the voltage just right.

The nominal voltage in the US has gradually crept up over the years, I suspect to squeeze a bit more capacity out of the existing grid but I don't really know. In the early days it was 110/220, then it was 115/230, then it rose to 117/234, and finally to what it has been throughout most/all of my own life, the 120/240 that we have today. Quite a few people still refer to it by the old ratings though.

[Spork Schivago]

Note that "120VAC - 0 - 120VAC" is the same thing as "split-phase".

None of the HPE PDU are designed to handle split-phase.  They are all designed for schemes where Neutral = Ground.

If you connect any of those HPE PDU things to domestic split-phase where Neutral = 120VAC, you are setting up a situation that is dangerous for both equipment and people.

That is why a transformer is need to convert 120-0-120 ("split-phase")  into 240-0 ("single-phase")

I agree the transformer is needed.   That's why I posted that in my second post I think.   I just wasn't sure what transformer.   But then people started suggesting that I should rewire the PDU, etc.

I called HPE again and verified that we do need the 1400 watt PSUs that only come in 240VAC single-phase.   I had asked you if 120-0-120 was split-phase and you said NO!!!!   So that confused me a bit, but I think I worded it weirdly.

Sending back the PDU and replacing it with a PDU that handles split phase isn't an option because the PSUs cannot run off split-phase.   They won't power up, they won't provide power to the servers.   So, we need the transformer, even if people think it's a hack job or dangerous or stupid or whatever.   That appears to be our only option at this point.

[Monkeh]

the PSUs cannot run off split-phase.   They won't power up, they won't provide power to the servers. 

And you know this how?

[Spork Schivago]

Looks like you like to ignore simple facts.

In the USA the standard electrical outlet is 110-120 volts 60hz.

All 220-240 volt stuff uses different connectors. Because of the difference people take more care.

Think of how many people in the USA have used computer power cords. For the USA the end that connects to a computer is 115volts. For a lot of the world that is 220volts but not in USA.

So now you have people seeing the computer end thinking 115volts and connecting an extension cord to your PDU, but that is not 115 volts. A part of safe is knowing what to expect.
So what is a safe European standard is not as safe in the USA due to common thought.

The added transformer is creating a safe NON-USA standard in addition to wasting power. That transformer will get hot, and that is a waste of power. 

One thing you might like to know is that 220 volt 60hz is more dangerous then 220 volt 50hz. The 60hz has a greater chance of messing up your heart beat then 50hz.

If you want real safe 220 volts using a USA split phase( 220 Volts with a neutral center tap) you use a four wire connection. The forth connection the safety ground.
Unlike the rest of the world USA 220 volt equipment often has some 115 volt loads.

C

We need 240VAC, again, for the server, not 220VAC, although it would run on 220VAC.   Most of our equipment is NOT from the USA.   The cords to power these devices are NOT what you find with a NORMAL USA bought PC, so I highly doubt anyone who is allowed to be around the rack will try plugging anything into the PDU.    I mean, simple fact, strangers aren't going to be down here, and if they are, they're breaking the law.   Eventually, we have to worry about my daughter, but that's a long ways away, and even then, she cannot physically get into the rack to plug anything into the PDU.   Ohm's law shows us if we double the volts, we cut the current draw in half.   200v * 2 amp = 400 watts.   20 amp * 20v = 400 watts.    I think I'd rather get shocked, if I had to get shocked, at the 200v, 2 amp, rather than the 20 amp.

I have no idea how anyone is going to plug any cords into the PDU, I don't know what you think the inputs look like, but you physically cannot take a normal PC cord and plug it into the PDU.   You need special cords....most of our energy hungry equipment is designed to run off 240VAC, but most of it can go down to 100VAC.   I mean, we have some American made workstations, but they're not going into the rack at all, and aren't being powered by this PDU.   A lot of stuff came from Germany.   There's usually no switch on these pieces of equipment to flip.   They say 100VAC - 240VAC.

I mentioned in a previous post that security was our responsibility and we get audited, where some people from some companies come in and check to make sure everything is up to their standard.   We get a report on what needs to change, if anything, and it's our responsibility to change what they list.   Once we wire up the 15kVA transformer (or higher someone to wire it up for us), we'll have to have yet another one of those pesky audits.

There's security in place.  Maybe you can take comfort in knowing that currently, no one who is specifically supposed allowed in the datacenter can get into the datacenter without doing a lot of illegal work?   This isn't a playroom.   The idea is though, we do our own thing once these contracts are up, and hopefully, later on in life, our daughter takes interest.   If not, that's okay, we'll love and accept her no matter what.   That's years down the road before we burn that bridge though.

Heck, do you know how hard it was to say no to the three phase installation?   We were talking over 50,000$ and almost went for it, because then we can purchase stuff that's a bit more suited to our task at hand.   I feel better having a PDU hooked up with a backup sitting on the shelf in case one shits the bed, rather than daisy chaining a whole bunch to try and get my systems running.

220 230 and 240 volts are all the same.
Voltage wise all of those are acceptable. *

Same thing with 110 115 and 120, all of them acceptable.

In the US the nominal is 120 and 240, but it's quite common for people to say 110 and 220 Etc.

I'm not familiar with the UK at all, but I think their nominal voltage is 230 volts? But the specification allows anywhere from 220 to 240 or something like that.

*Except in some special cases, mainly on large equipment that has its own transformer built-in, then there are multiple Taps to get the voltage just right.



Sent from my Moto x4 using Tapatalk

Yes, and our power supplies can take anything from 220VAC - 240VAC, but run optimally with 240VAC.   Thankfully, here, we actually have 120VAC when I measure the receptacles and not 115VAC.   The transformer will be an Edison, but they're literally the exact same thing as Acme Electronics.   Same catalog number, everything.   Hopefully, the transformer will put out 240VAC and not something lower, like 220VAC or 230VAC.

[Spork Schivago]

IMHO while I think you could install this with minimal problems you really should get an electrical engineer or commercial electrician that is familiar with something along these lines to have a plan drawn up and run it past your electrical inspector for the city and make sure everything will be okay.

You seem very concerned with security and Audits and having it done as right as it can be and all of that stuff;
 so having this planned out by a professional and approved by the inspector before you start doing things would be highly important. IMO

I would bet your insurance is going to absolutely require that.



Sent from my Moto x4 using Tapatalk

Yes, even though I'll be installing it, I'm going to be running it by professionals before I actually even touch anything.   It's out of my league a bit, and I will learn, but because of the dangers involved, I have no choice but to run it by professionals first.   Heck, I'm still having a hard enough time trying to understand how to wire it properly to begin with.   I will not take chances and just randomly guess or say yeah, I think this is right.   I just thought that was assumed, but yeah, that's the plan and was from the git go.   I might be able to get the company in my city that I'm working with to send one of their guys over, I dunno.   But I still want to wire it up, I don't want them doing it for me.   I just need them to double check everything and make sure it's correct before I go to the city, and watch me while I'm wiring it up, to make sure I don't make any horrible mistakes.

[Spork Schivago]

Mr. Crowley certainly has more patience than I. 
When stated that

“None of the HPE PDU are designed to handle split-phase.  They are all designed for schemes where Neutral = Ground.”

I believe He may have overlooked the P9S13A, as I previously posted, states it is for North America and Japan as it is rated for 200 -240V, uses a standard L6-30P plug (208-240V 3 pole twist lock labeled L1, L2 and Ground in the USA) and it has 2ea 2pole 20a breakers, one for each level of the PDU.  It also has the exact same receptacles as the one chosen by Spork. 
I’m not trying to rag on Mr. Crowley here, but I still think two of the P9S13A deserve more consideration especially since Spork has stated that he may expand his power requirements.  It would eliminate the need for a transformer unless his servers specifically need a grounded neutral which is very doubtful for SMPS typical server power supplies. 
Bratster’s drawing is a fine example of how to install a transformer; with the breaker panel on the output and proper breakers installed I believe it would pass any reasonable inspection.  However there are inspectors out there that kind of make up their own rules.

I appreciate the suggestion again for the P9S13A, but as Mr. Crowley had previously stated (which I was unaware of), these PDUs put out what they're fed.   So if they're fed a split-phase 120VAC - 0 - 120VAC source, they're going to output a split-phase 120VAC - 0 - 120VAC source, thus, we would not be able to use it.   We would still need the 240VAC - 0 - 0 for the PSUs (Power Supplies) that are in the servers.   If that makes since to you.   Unless I am misunderstanding something, and the P9S13A can actually provide single phase 240VAC on the output....

[Spork Schivago]

Certainly Spork would be better off with something he can connect directly to his split-phase domestic service as @Gregg observes.  It seems unfortunate that he selected that particular PDU.  The "documentation" provided by HPE leaves a great deal to the imagination from lack of useful details.

It's not like we actually just randomly picked a PDU Mr. Crowley.   We had a power assessment done for the server and where told we could only power our servers with one model PSU, which is 240VAC single-phase.    Then, after that, the HPE technicians found a suitable PDU for our rack environment.   I let those people make the decisions like that, so if something goes wrong, it falls back on them, not me.    But according to them, anything less than 1400 watt, our servers aren't going to power on at all with the hardware that we have in there.   And for the PSU, there was only one choice they provided us with, which expects the 1-phase 240VAC.    I mean, to use a split-phase service, we'd have to ditch some hardware, or go through another company.

We cannot mix and match equipment either, or it voids the warranty.   I don't necessarily mean we cannot go for a PDU made by a different company, but because we have HPE servers, we need to use HPE RAM, HPE Power Supplies.   If we don't, and something breaks, even if it's not related to us using something that isn't HPE branded, they will use that as an excuse to not warrant the hardware.   (one of those, oh, we see you're using non-qualified power supplies.   We're not going to replace your broken really expensive CPUs because you used unapproved PSUs.   For all we know, those PSUs killed your CPUs).

[Spork Schivago]

Actually Split-phase can be safer.

Yes, that all may be true, but none of it is beneficial (or even relevant) to the specific case at hand.
Bottom line: The PDU appears to be designed to have Neutral = ground and connecting split-phase to it is dangerous.

And would be not only dangerous, but wouldn't work.   The equipment that the PDU powers is designed to run off 1-phase 240VAC.   Now, if we were to hook up some workstations (not desktop's, but actual workstations), they might be designed to run off split-phase or even 120VAC.   The switch is made to run off single phase (either 120VAC or 240VAC) but not split-phase 120VAC - 0 - 120VAC.   I don't know if it'd turn on at all if we tried, but it isn't right.

Then the servers themselves, as we verified once again, are designed for single phase 240VAC but learned they won't even power on if we attempt to feed them split-phase.   This is probably a safety feature.

I don't like using a 240VAC transformer anymore than some of you guys, but I don't see any other options here, unless we ditch all the money we've invested in all this very expensive equipment and go for another vendor, but chances are even then, we'll need the single phase 240VAC.    Unfortunately, when you're dealing with equipment that requires a lot of power and is commercial grade, there aren't too many options.   It was hard enough just finding stuff that wasn't designed for 3-phase.   Most of the stuff was for 3-phase.   It would have been easier, but much, much, much more expensive, to have 3-phase ran to the house, and then purchase the 3-phase equipment.

[Monkeh]

Then the servers themselves, as we verified once again, are designed for single phase 240VAC but learned they won't even power on if we attempt to feed them split-phase.   This is probably a safety feature.

This seems unlikely. There's no safety benefit.

[Spork Schivago]

Actually Split-phase can be safer.

First you have GFCI or RCD to think about.
To reduce EMI or RFI X-cap's or Y-cap's are used. With two wire power and one side Neutral you are connecting 1/2 AC voltage to somethiing, the Neutral lead or safety ground. To work around this the GFCI or RCD has to be made less sensitive. With the center Neutral you have 0 volt AC EMI/RFI connected to Neutral so a more sensitive GFCI/RCD is possible..

There is no perfect wire so there is always a voltage drop on the Neutral lead making it NOT ground. A short from Neutral to something is connecting the voltage drop to something and not detected with fuse or circuit breaker in the hot lead. With split-phase this is detected. Shorts like this do happen and can have many watts of power turned in to heat.

Then you have 1/2 voltage difference to actual ground, again safer

The big cost is often just the one added wire and dual breakers.

Equipment designed for split-phase can be designed three ways.

1. You have Equipment that needs some 110-120 for internal use in addition to 220-240. Here three wire or safer 4 wire connection.

2. like above but with no 110-120 internal use so that the Neutral lead supplies no power.

3. A variation of #2 is Two hots and where Neutral lead is just used for a safety ground.

Three phase is just a shift to three hots vs two hots.

C

Three phase is far from just a shift to three hot leads.  There are several methods of connection used in the US, but all of the large data centers I have worked with use 480 volt 3ph UPSs connected to 208/120V transformers and then breaker panels.  Several customers had large cabinets that had 40 amp 208V 3ph power supplied.  3ph when rectified has far less ripple than single phase and the 3ph SMPS are more efficient.   

Neutral conductors should never be used as ground connectors.  True, there are a few cases where the NEC allows a ground conductor to carry a small neutral current; but I would never wire my house in such a manner, even if it is officially OK. 

Back to the subject at hand; Richard Crowley is absolutely correct and it is sad that Spork purchased the wrong PDU.  It isn’t our fault he didn’t ask first and now there isn’t any way to easily fix the situation short of taking it apart and seeing if it can be modified to install 2 pole breakers and to ensure the switching mechanism switches both hot legs of the 240V. 

If I were in Spork’s shoes, I would try to return the PDU on the grounds that they didn’t properly describe it in their literature and instead purchase two of the P9S13A units if he needs the capability to switch each branch circuit remotely. 

Let’s consider the possible unsafe modes of failure using the P9S16A PDU:

Suppose there is an internal ground fault in one of the server power supplies that is from the hot without the single pole breaker.  The single pole breaker doesn’t respond and the fault remains until the 40 amp two pole breaker trips after things catch fire.  Or the fault gets to the point where it blows up the power supply and possibly ruining the whole server.  If the 40 amp breaker trips, and nothing much else happens your whole system still goes down until you figure out the problem.  Assuming your server racks/cabinets are properly grounded; if they are not, you could be in for the shock of your life.

Suppose you figure out there is something wonky with one of the server power supplies and you turn it off remotely because you are not at home; but the PDU switch only turns off one hot leg.  Failure modes are the same as above.

I’m sure others on the forum could add to this list.

This is getting old guys.   It's not like I just surfed the net and randomly picked a PDU.   I'm running a business, so I call one of my VARs, I tell them what our requirements are.   They place a call to one of the various companies.   I like HPE, so I wanted HPE.   At first, we didn't have income to purchase everything we needed.   This is how most start-up companies operate.   They don't make a return for 2 years or so.   We got lucky and made a return early on, which allowed us to purchase the upgrades to do what we wanted.   But then we called our VAR and said hey, because we have x, y, and z added to the servers now, will the 120VAC 500 watt PSUs that are currently in the servers handle the new load?   They say let me forward that along to our HPE technicians.    They come back and say no, you need the 1400 watt PSUs part number <blah>.   We purchase the PSU part number <blah> and they say you also are going to need the PDU part number <blah>.    Our only other option was 3-phase, and if anything, we should be saying it's sad that Spork couldn't afford to get 3-phase ran to his house so he could purchase the 3-phase equipment that would be available to him.   We also need a UPS, but eventually a whole home generator with an automatic transfer station.

It'd be like me saying it's sad that you are running 3-phase to your rack.   You made a mistake in purchasing your equipment and should be running split-phase to your rack.   Your rack cannot handle split-phase, it needs 3-phase.   Why?   Because the equipment was designed for 3-phase, just like our equipment was designed for 240VAC single phase, not 120VAC - 0 - 120VAC split-phase.

I thought this was a simple question, I didn't expect 6 pages of people trying to get me to switch to something that just won't work, and granted, I guess it's more my fault for not giving out enough information (such as the power supplies we use, the exact equipment we use, etc), but my fear is violating the NDAs that we signed.   There's some claus that talks about us paying a lot of money if we violate it.    We have people working for us that have to sign an NDA, but we as well had to sign NDAs.   We have on-site and off-site record storage where there's different levels that different employees have access to.   There's the TRADE SECRET level, the CONFIDENTIAL LEVEL, and then the GENERAL level.   Our employees get access to the GENERAL level documents, which include stuff such as how to connect to the VPN tunnel, how to use the two factor authentication properly, what to do if there is a suspected compromise, SOPs, etc.

I don't know why everyone assumes I purchased the wrong PDU.   I don't know why almost everyone is suggesting I switch to a PDU that supports split-phase.   I said I need 240VAC single-phase and that's what I need.   I just thought in a professional environment, there'd be a lot less this is what I think you need stuff going on or if it was me, I would have done it this way or that way, or for my situation, split-phase works best, therefore, for your situation, it does as well kinda stuff.   I just thought I'd get a nice answer saying this is how you can achieve single phase 240VAC, like Mr. Crowley suggested, and a few others.

[Spork Schivago]

Then the servers themselves, as we verified once again, are designed for single phase 240VAC but learned they won't even power on if we attempt to feed them split-phase.   This is probably a safety feature.

This seems unlikely. There's no safety benefit.

You are saying there's no safety to the equipment that was designed to run off 240VAC single phase, 120VAC - 0 - 120VAC split phase?   Didn't we just go over all the dangers to doing that with the PDU?    Surely there are dangers to the server as well.    I cannot think of any other reasons as to why HPE would design the PSUs not to turn on at all if we tried feeding them 120VAC down the L/+ line, and 120VAC down the neutral line....

[Spork Schivago]

the PSUs cannot run off split-phase.   They won't power up, they won't provide power to the servers. 

And you know this how?

By talking to HPE directly, instead of going through my VAR?   I have a direct phone number I can give you, if you'd like to verify this information.   I can PM you the part number to the PSUs and you can talk to them directly and ask them for yourself if you don't believe me.

[IanB]

Then the servers themselves, as we verified once again, are designed for single phase 240VAC but learned they won't even power on if we attempt to feed them split-phase.   This is probably a safety feature.

A couple of puzzles with this are:

1. If you take the two line conductors from a split phase supply then that is, electronically, a single phase 240 V supply. The equipment being supplied cannot tell the difference between a 120-0-120 supply and a 240-0 supply unless it specifically measures the line-ground potential difference and acts on it. That seems unlikely as there would be no point.

2. A 240-0 single phase supply is nonstandard in the USA. So any equipment purchased in the USA for use in the USA market is unlikely to have this requirement--for the simple reason that nobody would have a suitable power supply for it. It makes no sense that the vendors would require customers to arrange a special installation with custom wiring, transformers and so forth just to use their equipment. Nobody would be prepared to stump up the cost.

The short answer is that equipment appears to come in two flavors: North America and "Worldwide", where "Worldwide" is everywhere except North America. It is logical that if servers, PSUs and PDUs are purchased with a North American specification for use within North America then they will be compatible with standard North American power distribution arrangements.

In North America the standard arrangements are 120-0 single phase, 120-0-120 split phase, or 208-0 single phase (derived from a three phase transformer). There could be three phase arrangements, but those are not under consideration here.

[Monkeh]

Then the servers themselves, as we verified once again, are designed for single phase 240VAC but learned they won't even power on if we attempt to feed them split-phase.   This is probably a safety feature.

This seems unlikely. There's no safety benefit.

You are saying there's no safety to the equipment that was designed to run off 240VAC single phase, 120VAC - 0 - 120VAC split phase?   Didn't we just go over all the dangers to doing that with the PDU?    Surely there are dangers to the server as well.    I cannot think of any other reasons as to why HPE would design the PSUs not to turn on at all if we tried feeding them 120VAC down the L/+ line, and 120VAC down the neutral line....

There are no dangers with the individual power supplies. I think it extremely unlikely they designed them not to operate off split phase.

the PSUs cannot run off split-phase.   They won't power up, they won't provide power to the servers. 

And you know this how?

By talking to HPE directly, instead of going through my VAR?   I have a direct phone number I can give you, if you'd like to verify this information.   I can PM you the part number to the PSUs and you can talk to them directly and ask them for yourself if you don't believe me.

The answer will be given to me the same way it was given to you: A person on the other end of the phone with no knowledge whatsoever of power supplies reads '240V single phase' off the datasheet and says 'it will only work with this'.

[Spork Schivago]

Then the servers themselves, as we verified once again, are designed for single phase 240VAC but learned they won't even power on if we attempt to feed them split-phase.   This is probably a safety feature.

A couple of puzzles with this are:

1. If you take the two line conductors from a split phase supply then that is, electronically, a single phase 240 V supply. The equipment being supplied cannot tell the difference between a 120-0-120 supply and a 240-0 supply unless it specifically measures the line-ground potential difference and acts on it. That seems unlikely as there would be no point.

2. A 240-0 single phase supply is nonstandard in the USA. So any equipment purchased in the USA for use in the USA market is unlikely to have this requirement--for the simple reason that nobody would have a suitable power supply for it. It makes no sense that the vendors would require customers to arrange a special installation with custom wiring, transformers and so forth just to use their equipment. Nobody would be prepared to stump up the cost.

The short answer is that equipment appears to come in two flavors: North America and "Worldwide", where "Worldwide" is everywhere except North America. It is logical that if servers, PSUs and PDUs are purchased with a North American specification for use within North America then they will be compatible with standard North American power distribution arrangements.

In North America the standard arrangements are 120-0 single phase, 120-0-120 split phase, or 208-0 single phase (derived from a three phase transformer). There could be three phase arrangements, but those are not under consideration here.

Keep in mind, most of the equipment that is available for me is designed to run off of 3-phase.   There aren't really any 120VAC options.   And these power supplies are expensive, the server is very expensive.   The CPUs are Xeon E5-v2699v4's, so maybe HPE techs are wrong?   But they checked.   They just didn't give me an answer.    They came back and said no, the power supplies would not even power on with split phase.   So, there is a good chance that they have circuitry to detect the voltage.   Keep in mind, we're talking just the server, with options well over 100,0000$ for possible configurations.    This isn't consumer grade equipment, it's Enterprise grade equipment.   The mainframe is Enterprise grade, the switch is Enterprise Grade, the servers are Enterprise grade, etc.    The GPU alone, they make a commercial model for consumers, but I cannot use that.   I need a special version made for this server, even though the model numbers are the same.   The price tag is not.   And it's design is not the same either.

There's North American and Worldwide, but when you reach a certain level, it doesn't really matter anymore.   I believe 3-phase is the same here as it is anywhere.   And we were lucky that this PDU was available without needing 3-phase.    Our PSUs do not say 120-240VAC.   They're 220-240VAC.    I guess there's a chance HPE techs where wrong?   But I'm not going to try it and risk damaging the equipment because of the price we've invested this year alone, let alone all the previous years on equipment.   The best I can do is give you my contact number for HPE and you can talk to them.

Heck, one of the options for my server is a DC power supply that supports 380VDC.   I don't think that is common in households, but these servers are Enterprise grade and generally aren't ran in households.   Maybe that's where we're running into trouble?   Without knowing the exact equipment, people just speculate as to what we have.   I can say each CPU cost over 4,000$ and we got them at rock-bottom price, where our VAR did not make any money at all on them.    He did this because I was in the Marine Corps.   I've recently switched doctors after this memory doc (who said he was in the military) went and told my civilian doctor (who ordered the memory tests) that I had PTSD.    And that sucked, but they got me on new meds that seem to be helping, when I remember to take them.

If I was out of line, I apologize.   I know you guys are just trying to help me get the best solution and safest solution.   It's just a bit frustrating and I'm not really used to dealing with that.   I got access to this site that I'm working through which helps you transition from the military world to the civilian world and run a business successfully.

A lot of this equipment isn't sitting around on a desk waiting to be sold.   When I place the order with one of my VARs, they contact the various companies, and the company specially makes it for me.   That was the case with the PDU, that was the case with the processors.   I don't know about the PSUs though.   We might be able to find a tear down for the PSU and see what happens?

It's fancy and supports other features as well, and maybe that's why split-phase won't work?   They're HPE's Flex Slot Platinum Plus Hot Plug, 1400 watt, part number: 720620-B21

[Spork Schivago]

Then the servers themselves, as we verified once again, are designed for single phase 240VAC but learned they won't even power on if we attempt to feed them split-phase.   This is probably a safety feature.

This seems unlikely. There's no safety benefit.

You are saying there's no safety to the equipment that was designed to run off 240VAC single phase, 120VAC - 0 - 120VAC split phase?   Didn't we just go over all the dangers to doing that with the PDU?    Surely there are dangers to the server as well.    I cannot think of any other reasons as to why HPE would design the PSUs not to turn on at all if we tried feeding them 120VAC down the L/+ line, and 120VAC down the neutral line....

There are no dangers with the individual power supplies. I think it extremely unlikely they designed them not to operate off split phase.

the PSUs cannot run off split-phase.   They won't power up, they won't provide power to the servers. 

And you know this how?

By talking to HPE directly, instead of going through my VAR?   I have a direct phone number I can give you, if you'd like to verify this information.   I can PM you the part number to the PSUs and you can talk to them directly and ask them for yourself if you don't believe me.

The answer will be given to me the same way it was given to you: A person on the other end of the phone with no knowledge whatsoever of power supplies reads '240V single phase' off the datasheet and says 'it will only work with this'.

No, they did not just give me an answer.   They went and checked the design specs, like they always do.   This isn't consumer grade equipment, it's Enterprise Grade equipment.   So like IanB was saying, 120-0-120VAC is common in North America and most products sold would be designed to work with that.   Maybe with consumer grade equipment, yes.   But most options I have available are 240V single phase or 3-phase or high DC voltage, which is used in telecommunication centers mainly (from what I've been told).

If the datasheet doesn't tell us and only lists supply voltage as 220VAC - 240VAC (not on just this, but some of the other equipment as well) and the manufacturer is claiming it will only work with 240VAC single phase, what would you do?    Tear it apart to check and void the warranty and your really expensive equipment?    Or would you assume they know what they're talking about, seeing how they're the ones who built it?   Or would you just disregard them and wire it up for split-phase?   After someone suggested that with the PDU, I almost did that, because I thought the people here knew what they was talking about, but I guess I didn't give enough info.   I should have posted a datasheet or something, so they could see for themselves all the info.    I do have some stuff I bought from Germany for my previous hobby, that was specially designed to run off USA power, but I had to specifically say I needed it for the North American wiring, and that's not really enterprise grade equipment.   Just some Weller soldering stations, preheaters, hot air rework stations, etc.   Nothing too fancy or expensive.

Enterprise grade hardware isn't the same as regular hardware you buy at Walmart or Home Depot.

[Spork Schivago]

Output on those PSUs are 12v, 117 amp!   That's a good amount of current.

[Monkeh]

But they checked.   They just didn't give me an answer.    They came back and said no, the power supplies would not even power on with split phase.   So, there is a good chance that they have circuitry to detect the voltage.

There's an equally good chance they didn't understand what the test setup was meant to be. Sorry, but I just can't see any reason whatsoever they'd care whether it's a single phase supply with a ground referenced neutral or not. Being Enterprise with a capital E doesn't change that.

Heck, one of the options for my server is a DC power supply that supports 380VDC.

That's what your 240VAC power supplies really run off. 240VAC rectified and boosted by a PFC controller to approximately 380VDC.

It's fancy and supports other features as well, and maybe that's why split-phase won't work?   They're HPE's Flex Slot Platinum Plus Hot Plug, 1400 watt, part number: 720620-B21

It's.. a really ordinary power supply sourced from at least two manufacturers (Delta and Flextronics). People run these types of off split-phase all the time.

No, they did not just give me an answer.   They went and checked the design specs, like they always do.

Design spec: 200-240VAC single phase. Your supply: 240VAC single phase. Yes, it's a split phase installation - the final load does not care about that detail.

Or would you assume they know what they're talking about, seeing how they're the ones who built it?

The ones who had multiple other companies independently design and manufacture a supply which is physically and electrically compatible. Nobody you spoke to specified, designed, tested, built, or was otherwise involved in the development of any of the several supplies with that part number.

This thread is going to keep going around in circles.

Change your PDUs for the type with double pole breakers and use your existing supply, or have an electrician (yes. really. please don't do it yourself.) install the transformer. Either will work.

Good luck with the heat problem.

Enterprise grade hardware isn't the same as regular hardware you buy at Walmart or Home Depot.

Where can I get Enterprise grade electrons for it?

[IanB]

It's fancy and supports other features as well, and maybe that's why split-phase won't work?   They're HPE's Flex Slot Platinum Plus Hot Plug, 1400 watt, part number: 720620-B21

OK, I did some reading around the HPE document library and the situation is clearer now.

This equipment is certainly intended for installation in commercial data centers and is not meant to see a home environment.

HP expects commercial power to be available in North America in two flavors of single phase: either 120 V AC ("low-line") or 208 V AC ("high-line"). The 208 V power would be derived from one leg of a three phase transformer and would be true 208-0 V single phase line to neutral.

HP does not expect 240 V AC single phase to be available in North America and their PDUs designated for the NA market are not specified this way. Their NA PDUs are specified for 200-208 V AC single phase input.

(Various flavors of three phase AC are also supported but they are not relevant here.)

The actual PSUs such as the HPE 1400W Flex Slot Platinum Plus Hot Plug Power Supply (720620-B21) that you quoted simply say "200-240 V, 50/60 Hz". There's nothing to indicate that the 240 V can't be derived from a split phase supply, but the split phase supply wouldn't be compatible with the PDU or the intelligent power management services.

So, in summary, what you have been told is correct. Your system needs a true 200-240 V AC single phase supply such as would be found in a commercial facility where it would come from one leg of a three phase utility transformer as 208 V AC. Since this is not available to you, you do indeed need a transformer to convert 240 V split phase to 240 V single phase line to neutral.

[Edit: Apparently I am wrong. The 208 V AC is not line to neutral, it is phase to phase with two hot legs and no neutral, similar to the 240 V split phase in a home. So maybe the transformer would not be needed if the P9S13A PDU were to be used instead of the P9S16A.]

Overall, your whole setup would work better in a commercial building.

[Spork Schivago]

You still don't get it.   We still have other equipment that requires 1-phase 240VAC, unless the technicians lied about that as well.   The people I talked to tonight was to _verify_ the information.    Pre-Sales is a hell of a lot different than post-sales.   Post sales are the REAL HP technicians that are actually building the units, the ones that my VAR deals with.

My VAR is a large VAR.   They have Microsoft people in the building, they have HPE technicians in the building, building HPE stuff, they have Lenevo people in the building.   These people are paid by HPE, Lenevo, etc.   I can have my Account Executive double check with the actual technicians that build the actual devices and have him tell me, once again, that it'll only run on 1-phase 240VAC.   I dunno why they did that.

If you feel there isn't a difference between enterprise grade and consumer grade equipment, I'm sorry, but you're just wrong.   With your datacenter, would you go buy a Vizio router for the gateway?   I highly doubt it.   You were the one who posted the datacenter pics with the three-phase, weren't you?   I would think out of everyone, you'd understand the most that most of the equipment you purchased is designed to run off 3-phase, not split phase or any of that shit.   Same with mine.   But you're right, going around in circles.   I'm still not 100% clear on how to wire the AC into the transformer.

Once again though, I will state, I am still getting a professional to go over the results before I hook anything up.   I'm not an idiot, and only an idiot would try to hook a transformer like this up without having any knowledge of how it works without seeking professional help first.   I've been saying that this whole time.   I just want to be the one who physically does the work and learns how it works (the transformer).   I've learned a lot from you guys since I posted.

When I said fancy features, I meant HPE Power Discovery Services (PDS) combines the HPE Intelligent Power Distribution Unit (iPDU) and HPE Flex Slot Platinum Plus power supplies with HPE Insight Control software to create an automated, energy-aware network between IT systems and facilities.

I could not go for the HPE Intelligent Power Distribution Unit.   So I cannot use that feature.   However, there's extra stuff near the adapter plugin that interacts with the iPDUs and sends information over the network and everything.

So before you leave, can you go over this PFC Controller a bit more?   How do people get 380VDC ran into their house / building, and why is it rectified and boosted to such a high voltage?   The output of the PSU is 12VDC.   Where does the 380VDC come into play?

Thanks.

[IanB]

Change your PDUs for the type with double pole breakers and use your existing supply, or have an electrician (yes. really. please don't do it yourself.) install the transformer. Either will work.

It's not clear that there are any HPE PDUs with double pole breakers. The HPE literature divides the product range into two categories: NA/Japan which expects 200-208 V AC single phase, or INTL which expects 220-240 V AC single phase. In either case it is clear that this voltage is measured line to neutral, as is typically found in commercial premises.

[Spork Schivago]

It's fancy and supports other features as well, and maybe that's why split-phase won't work?   They're HPE's Flex Slot Platinum Plus Hot Plug, 1400 watt, part number: 720620-B21

OK, I did some reading around the HPE document library and the situation is clearer now.

This equipment is certainly intended for installation in commercial data centers and is not meant to see a home environment.

HP expects commercial power to be available in North America in two flavors of single phase: either 120 V AC ("low-line") or 208 V AC ("high-line"). The 208 V power would be derived from one leg of a three phase transformer and would be true 208-0 V single phase line to neutral.

HP does not expect 240 V AC single phase to be available in North America and their PDUs designated for the NA market are not specified this way. Their NA PDUs are specified for 200-208 V AC single phase input.

(Various flavors of three phase AC are also supported but they are not relevant here.)

The actual PSUs such as the HPE 1400W Flex Slot Platinum Plus Hot Plug Power Supply (720620-B21) that you quoted simply say "200-240 V, 50/60 Hz". There's nothing to indicate that the 240 V can't be derived from a split phase supply, but the split phase supply wouldn't be compatible with the PDU or the intelligent power management services.

So, in summary, what you have been told is correct. Your system needs a true 200-240 V AC single phase supply such as would be found in a commercial facility where it would come from one leg of a three phase utility transformer as 208 V AC. Since this is not available to you, you do indeed need a transformer to convert 240 V split phase to 240 V single phase line to neutral.

Overall, your whole setup would work better in a commercial building.

THANK YOU!!!!   That's what I've been trying to say!   I didn't know I'd have to go into sooooo much detail to get people to understand.   Yes, this equipment is designed for a COMMERCIAL building, not HOME!!!   But the problem is getting 208VAC to our house.   That's just as expensive as any of the other 3-phase, hence the reason we had to go with the 240VAC European factor.    Normally, a commercial facility would have 3-phase.    It's that iPDU stuff, I believe, that makes this PSU NOT boot up with split-phase, despite what other people say.   It gets frustrating repeating myself, but thank you for doing the research!   I got hurt in the Marine Corps.   It caused some brain damage.   My brain doesn't work the same way as other people, so it's hard to word things properly or talk properly sometimes and I cannot get the right words out, no matter how much I try.   This makes it frustrating and people always think I'm being an ass, but I'm not trying to be, I'm just trying to explain it the best I can.

But it's weird, although I can't tell people how to do certain things or remember, I can still do them very well, much better than before, like programming.   I don't know how.   The memory specialist doc I saw said it's like losing a sense, the other senses tend to get better.   Part of my brain don't work right or at all, so he thinks other parts work better I guess.

Anyway, now that we finally got that out of the way and almost everyone can agree that I need true 240VAC 1-phase, can we get back to the transformer issue?   I'm still having a hard time understanding it.   Do you guys have any good documents that break down how they work and what taps are and stuff like that?

[Spork Schivago]

Change your PDUs for the type with double pole breakers and use your existing supply, or have an electrician (yes. really. please don't do it yourself.) install the transformer. Either will work.

It's not clear that there are any HPE PDUs with double pole breakers. The HPE literature divides the product range into two categories: NA/Japan which expects 200-208 V AC single phase, or INTL which expects 220-240 V AC single phase. In either case it is clear that this voltage is measured line to neutral, as is typically found in commercial premises.

Yes, hence the reason we could ONLY go for the 240VAC PDU!   The 3-phase is too expensive.   I mentioned that early on, but maybe my message wasn't clear?   I said most of the equipment is for 3-phase, but after talking to the electricity company and the professional licensed electrician, we could not afford it.   So we had to go with the 240VAC one.   I was saying the Enterprise grade stuff is not like the residential stuff.  But for some reason, people just don't understand that.   Thank you for helping me word things correctly!

[IanB]

So before you leave, can you go over this PFC Controller a bit more?   How do people get 380VDC ran into their house / building

(they don't...)

, and why is it rectified and boosted to such a high voltage?   The output of the PSU is 12VDC.   Where does the 380VDC come into play?

The 380 V DC is apparently a standard found in commercial data centers. The 380 V DC is created inside the building from the normal AC supply, it is not brought in from outside.

As to why it would be used, this is about how power supplies work. In order to get the 12 V DC, a power supply first rectifies the AC into high voltage DC, and then special electronics take the high voltage DC and convert it down to the 12 V. Instead of each power supply individually rectifying the AC, it is more efficient to have a single giant rectifier somewhere in the building and then distribute this around to all the servers.

[IanB]

I got hurt in the Marine Corps.   It caused some brain damage.   My brain doesn't work the same way as other people, so it's hard to word things properly or talk properly sometimes and I cannot get the right words out, no matter how much I try.   This makes it frustrating and people always think I'm being an ass, but I'm not trying to be, I'm just trying to explain it the best I can.

Don't worry about it. There's nothing wrong with what you've been saying, it's just that what you are doing is so far outside normal expectations that people are having trouble understanding. People don't normally try to set up a commercial data center in their basement.

[oPossum]

HP expects commercial power to be available in North America in two flavors of single phase: either 120 V AC ("low-line") or 208 V AC ("high-line"). The 208 V power would be derived from one leg of a three phase transformer and would be true 208-0 V single phase line to neutral.

240 and 480 phase to phase is also common commercial power.

208 is phase to phase, not phase to neutral. Phase to neutral is 120.

That is why there are two pole breakers on those PDU.

240 phase to phase would not be a problem.

[IanB]

Change your PDUs for the type with double pole breakers and use your existing supply, or have an electrician (yes. really. please don't do it yourself.) install the transformer. Either will work.

It's not clear that there are any HPE PDUs with double pole breakers. The HPE literature divides the product range into two categories: NA/Japan which expects 200-208 V AC single phase, or INTL which expects 220-240 V AC single phase. In either case it is clear that this voltage is measured line to neutral, as is typically found in commercial premises.

OK, I stand corrected. The P9S13A does have a double pole breaker, as listed here: https://h20195.www2.hpe.com/v2/GetDocument.aspx?docname=a00002909enw

So it does appear that 240 V line to line or phase to phase should be acceptable for this particular PDU.

[IanB]

208 is phase to phase, not phase to neutral. Phase to neutral is 120.

That is why there are two pole breakers on those PDU.

I see. Makes sense.

[Bratster]

@Spork

What are you not clear on understanding of how to wire up the Transformer?

The drawing I sketched out gave you the basics of what is going on with it.

Let's stop beating this dead horse.

Whether we like it or not you need a 240-volt line to neutral power service.

The only way you're going to get that from your existing house supply is with a Transformer.

So focusing on that point, what are you having trouble understanding so that everybody can help you out in that aspect?


PS. This post was not meant to come off as offensive or anything like that, I'm sleepy and it looks like this thread is starting to go in circles again.

Night all

Sent from my Moto x4 using Tapatalk

[Monkeh]

You still don't get it.   We still have other equipment that requires 1-phase 240VAC, unless the technicians lied about that as well.   The people I talked to tonight was to _verify_ the information.    Pre-Sales is a hell of a lot different than post-sales.   Post sales are the REAL HP technicians that are actually building the units

Building = slotting them together like Lego.

If you feel there isn't a difference between enterprise grade and consumer grade equipment, I'm sorry, but you're just wrong.

In terms of how a power supply is designed and functions.. no, there really isn't a difference. You can throw around buzzwords and price tags all you like, the power supplies for those servers work just like any other.

You were the one who posted the datacenter pics with the three-phase, weren't you?

No.

When I said fancy features, I meant HPE Power Discovery Services (PDS) combines the HPE Intelligent Power Distribution Unit (iPDU) and HPE Flex Slot Platinum Plus power supplies with HPE Insight Control software to create an automated, energy-aware network between IT systems and facilities.

Some simple firmware and a lot of marketing speak. Nothing to do with how the input is handled.

I need true 240VAC 1-phase

Everyone can agree on this. And we can also all agree.. you have true 240VAC single-phase. It happens to have a centre tap making it split-phase distribution which is messing you (and the 'technicians' at HPE) up.

Whether we like it or not you need a 240-volt line to neutral power service.

No he doesn't. He needs a PDU capable of safely distributing his centre-tapped 240V phase, rather than a huge lump of iron hanging on his wall.

[Bratster]

You still don't get it.   We still have other equipment that requires 1-phase 240VAC, unless the technicians lied about that as well.   The people I talked to tonight was to _verify_ the information.    Pre-Sales is a hell of a lot different than post-sales.   Post sales are the REAL HP technicians that are actually building the units

Building = slotting them together like Lego.

If you feel there isn't a difference between enterprise grade and consumer grade equipment, I'm sorry, but you're just wrong.

In terms of how a power supply is designed and functions.. no, there really isn't a difference. You can throw around buzzwords and price tags all you like, the power supplies for those servers work just like any other.

You were the one who posted the datacenter pics with the three-phase, weren't you?

No.

When I said fancy features, I meant HPE Power Discovery Services (PDS) combines the HPE Intelligent Power Distribution Unit (iPDU) and HPE Flex Slot Platinum Plus power supplies with HPE Insight Control software to create an automated, energy-aware network between IT systems and facilities.

I need true 240VAC 1-phase

Whether we like it or not you need a 240-volt line to neutral power service.

No he doesn't. He needs a PDU capable of safely distributing his centre-tapped 240V phase, rather than a huge lump of iron hanging on his wall.

Except he has already stated that he wants to use the equipment that he has...

So the only way for that power distribution unit to work correctly/safely is to have the correct power source coming into it.



Sent from my Moto x4 using Tapatalk

[Monkeh]

Except he has already stated that he wants to use the equipment that he has...

So the only way for that power distribution unit to work correctly/safely is to have the correct power source coming into it.

He doesn't need to have a grounded pole service. He might want to, but what he needs to do is get the right PDU and not burn money on a hunk of self heating iron.

[Spork Schivago]

So before you leave, can you go over this PFC Controller a bit more?   How do people get 380VDC ran into their house / building

(they don't...)

, and why is it rectified and boosted to such a high voltage?   The output of the PSU is 12VDC.   Where does the 380VDC come into play?

The 380 V DC is apparently a standard found in commercial data centers. The 380 V DC is created inside the building from the normal AC supply, it is not brought in from outside.

As to why it would be used, this is about how power supplies work. In order to get the 12 V DC, a power supply first rectifies the AC into high voltage DC, and then special electronics take the high voltage DC and convert it down to the 12 V. Instead of each power supply individually rectifying the AC, it is more efficient to have a single giant rectifier somewhere in the building and then distribute this around to all the servers.

I understand the need to rectify it in a PSU, but what I don't understand is why we simply cannot go directly to 12VDC.   Why is there a need to go to 380VDC first, and then use something like a step-down transformer or bridge rectifier to break it down even further?   Is that just to make it more clean?   Surely going from 380VDC to 12VDC would give us more current, right?   But going from 120VAC directly to 12VDC should allow us to draw equally as much current I'd think as going from 120VDC to 380VDC to 12VDC.   If anything, we'd have a little less current draw available because of the components voltage drops and their current draw, but I don't think that would be a lot, maybe I'm wrong.

[Spork Schivago]

I got hurt in the Marine Corps.   It caused some brain damage.   My brain doesn't work the same way as other people, so it's hard to word things properly or talk properly sometimes and I cannot get the right words out, no matter how much I try.   This makes it frustrating and people always think I'm being an ass, but I'm not trying to be, I'm just trying to explain it the best I can.

Don't worry about it. There's nothing wrong with what you've been saying, it's just that what you are doing is so far outside normal expectations that people are having trouble understanding. People don't normally try to set up a commercial data center in their basement.

Yes, I know.   And I should have just used the word datacenter instead of basement.   The goal is to generate enough revenue that we can rent a proper building and create a proper datacenter, but until then, we have to make do with what we have.

For what it's worth, before anyone asks, we have already okayed this with the city.   Originally, we were trying to purchase a house that was in the commercial zoning district, but two other people were already on it, and the crappy realtor we had suggested we highball them for more money than what we felt comfortable for.   The outside, they had redone and it looked gorgeous (the sellers), however, they appeared to run out of money and never got a chance to do the inside, which still had knob and tube wiring, fuses instead of breakers, lathe and plaster instead of drywall, and we decided to look elsewares.   We contacted the city and asked about running a business of this type in a residential zone.

It's allowed, so long as we follow all the rules, and we cannot advertise like you would if it was zoned commercially.   What I mean by that, we can put a small sign in the yard or in the window, but we can't have neon lights and big signs, etc.   We can't have a docking port for big rigs or any of that, but with the business we're doing, we aren't targeting the residential sector, so this isn't a big problem for us, minus trying to get help on forums when it comes to things like this thread.

[Spork Schivago]

Change your PDUs for the type with double pole breakers and use your existing supply, or have an electrician (yes. really. please don't do it yourself.) install the transformer. Either will work.

It's not clear that there are any HPE PDUs with double pole breakers. The HPE literature divides the product range into two categories: NA/Japan which expects 200-208 V AC single phase, or INTL which expects 220-240 V AC single phase. In either case it is clear that this voltage is measured line to neutral, as is typically found in commercial premises.

OK, I stand corrected. The P9S13A does have a double pole breaker, as listed here: https://h20195.www2.hpe.com/v2/GetDocument.aspx?docname=a00002909enw

So it does appear that 240 V line to line or phase to phase should be acceptable for this particular PDU.

But then we're back to the power supplies being fed split-phase, aren't we?   It wasn't me who picked out the PDU or the PSUs.   And like I've stated, HPE could have been wrong during their power analysis, but after their power analysis there was one power supply that was available, and only one, the one we have.    And then when it came to a proper PDU, there was no PDUs available that would work with our PSUs and our split-phase, however, there were ones available that would work with 1-phase 240VAC or the 3-phase.   And eventually, we went for the 1-phase 240VAC out of the choices, because of the 3-phase being too much.

[Spork Schivago]

HP expects commercial power to be available in North America in two flavors of single phase: either 120 V AC ("low-line") or 208 V AC ("high-line"). The 208 V power would be derived from one leg of a three phase transformer and would be true 208-0 V single phase line to neutral.

240 and 480 phase to phase is also common commercial power.

208 is phase to phase, not phase to neutral. Phase to neutral is 120.

That is why there are two pole breakers on those PDU.

240 phase to phase would not be a problem.

I'm trying to understand all this.   How does the 208VAC work exactly?   You say it's phase to phase, that's like my North American Residential Standard Panel Input 240VAC split-phase, right?    240VAC from one 120VAC hot, and from the other 120VAC hot line coming in.   Phase to Neutral is 120.   With 208, you say Phase to neutral is 120.   So the other phase is 88VAC?

And when a device can run off split-phase, does it combine the two phases internally to get the 240VAC or does half the circuit use 120VAC and the other half use 120VAC?

[Spork Schivago]

@Spork

What are you not clear on understanding of how to wire up the Transformer?

The drawing I sketched out gave you the basics of what is going on with it.

Let's stop beating this dead horse.

Whether we like it or not you need a 240-volt line to neutral power service.

The only way you're going to get that from your existing house supply is with a Transformer.

So focusing on that point, what are you having trouble understanding so that everybody can help you out in that aspect?


PS. This post was not meant to come off as offensive or anything like that, I'm sleepy and it looks like this thread is starting to go in circles again.

Night all

Sent from my Moto x4 using Tapatalk

Yes, your drawing was amazing.   It's the actual multiple configurations of the wirings that Mr. Crowley and I talked about, I'm still not 100% clear on that.   I understand what wires get tied together in transformer, but I'm not 100% clear on where the two 120VAC's would run to which wires in the transformer and where the neutral would run.   And then I'm not 100% clear on the output side, which wires would get ran to the new breaker panel.   I wasn't picturing the transformer running to a new panel, I was picturing the transformer running to the receptacle to power the PDU.   However, I think your drawing is the correct way to go and is what the electrician that I've contacted would have said, once he finds the time to get back to me.   He's good, he's expensive, but knows the codes and works generally with larger companies.   One of the businesses I deal with recommended him because when they cannot wire something up, they hire him.

They wire up furnaces, whole home generators, etc, so it's not often they need him, but when they do, he's always the one they call.   It takes him a while to get back to me for some reason though.

[Monkeh]

HP expects commercial power to be available in North America in two flavors of single phase: either 120 V AC ("low-line") or 208 V AC ("high-line"). The 208 V power would be derived from one leg of a three phase transformer and would be true 208-0 V single phase line to neutral.

240 and 480 phase to phase is also common commercial power.

208 is phase to phase, not phase to neutral. Phase to neutral is 120.

That is why there are two pole breakers on those PDU.

240 phase to phase would not be a problem.

I'm trying to understand all this.   How does the 208VAC work exactly?   You say it's phase to phase, that's like my North American Residential Standard Panel Input 240VAC split-phase, right?    240VAC from one 120VAC hot, and from the other 120VAC hot line coming in.   Phase to Neutral is 120.   With 208, you say Phase to neutral is 120.   So the other phase is 88VAC?

Each phase is 120VAC to the star point ('neutral'), 208VAC to each other. Three phases. As mentioned before, 'split phase' isn't really multiple phases: IT IS ONE PHASE with a centre tap.

And when a device can run off split-phase, does it combine the two phases internally to get the 240VAC or does half the circuit use 120VAC and the other half use 120VAC?

There are no halfs. Both hot conductors make for a single phase of 240VAC. That's all the load cares about. With the PDU it's a distribution concern - at loads it's irrelevant.

[tpowell1830]

Change your PDUs for the type with double pole breakers and use your existing supply, or have an electrician (yes. really. please don't do it yourself.) install the transformer. Either will work.

It's not clear that there are any HPE PDUs with double pole breakers. The HPE literature divides the product range into two categories: NA/Japan which expects 200-208 V AC single phase, or INTL which expects 220-240 V AC single phase. In either case it is clear that this voltage is measured line to neutral, as is typically found in commercial premises.

OK, I stand corrected. The P9S13A does have a double pole breaker, as listed here: https://h20195.www2.hpe.com/v2/GetDocument.aspx?docname=a00002909enw

So it does appear that 240 V line to line or phase to phase should be acceptable for this particular PDU.

But then we're back to the power supplies being fed split-phase, aren't we?   It wasn't me who picked out the PDU or the PSUs.   And like I've stated, HPE could have been wrong during their power analysis, but after their power analysis there was one power supply that was available, and only one, the one we have.    And then when it came to a proper PDU, there was no PDUs available that would work with our PSUs and our split-phase, however, there were ones available that would work with 1-phase 240VAC or the 3-phase.   And eventually, we went for the 1-phase 240VAC out of the choices, because of the 3-phase being too much.

Back to the 3 phase system, I think that you are being told $50k to install is what I read? This seems very outrageous, having done this myself in my area. The 3 phase power lines were 1/4 mile away and the power company charged me a modest $300 to install the pole and transformer, however, I had to sign a 3 year contract with a minimal $25 charge for the service. Mind you, this was in 1980, so I could see a factor of 10 at least on that price, but still can't get to the $50k figure. You would still need to provide a distribution panel and do all of the wiring, which I did myself in 1980.

Hope this helps...

[IanB]

But then we're back to the power supplies being fed split-phase, aren't we?   It wasn't me who picked out the PDU or the PSUs.   And like I've stated, HPE could have been wrong during their power analysis, but after their power analysis there was one power supply that was available, and only one, the one we have.    And then when it came to a proper PDU, there was no PDUs available that would work with our PSUs and our split-phase, however, there were ones available that would work with 1-phase 240VAC or the 3-phase.   And eventually, we went for the 1-phase 240VAC out of the choices, because of the 3-phase being too much.

Except that split phase in this context is not relevant. All you need care about is that it is a 240 V single phase supply. The P9S13A is designed and manufactured for the North American market and comes already fitted with a NEMA L6-30P plug that your electrician would have no problems with. It has 2-pole breakers which is what are needed for North American standards, and it can work with 200-240 V, which is compatible with the 240 V in your house. It is all good. Buying something that is not marked NA/JP is what has got you into trouble here.

A possible lesson learned here is not to rely on the vendor or salespeople to give technical advice. They are mainly interested in making the sale and taking your money. The best way to get advice is to engage an independent consultant with appropriate industry knowledge and experience, someone who will know how everything works and who is not just reading off sales brochures.

[Bratster]

@Spork

What are you not clear on understanding of how to wire up the Transformer?

The drawing I sketched out gave you the basics of what is going on with it.

Let's stop beating this dead horse.

Whether we like it or not you need a 240-volt line to neutral power service.

The only way you're going to get that from your existing house supply is with a Transformer.

So focusing on that point, what are you having trouble understanding so that everybody can help you out in that aspect?


PS. This post was not meant to come off as offensive or anything like that, I'm sleepy and it looks like this thread is starting to go in circles again.

Night all

Sent from my Moto x4 using Tapatalk

Yes, your drawing was amazing.   It's the actual multiple configurations of the wirings that Mr. Crowley and I talked about, I'm still not 100% clear on that.   I understand what wires get tied together in transformer, but I'm not 100% clear on where the two 120VAC's would run to which wires in the transformer and where the neutral would run.   And then I'm not 100% clear on the output side, which wires would get ran to the new breaker panel.   I wasn't picturing the transformer running to a new panel, I was picturing the transformer running to the receptacle to power the PDU.   However, I think your drawing is the correct way to go and is what the electrician that I've contacted would have said, once he finds the time to get back to me.   He's good, he's expensive, but knows the codes and works generally with larger companies.   One of the businesses I deal with recommended him because when they cannot wire something up, they hire him.

They wire up furnaces, whole home generators, etc, so it's not often they need him, but when they do, he's always the one they call.   It takes him a while to get back to me for some reason though.

I can't comment on how you wire the Transformer taps specifically as I didn't look at it.

But you would set it up for 240v in and out.

Forget about the neutral from your house, you don't use it in this application.

Only 120v line 1, 120v line 2 and ground.

On the output of the Transformer that's when you now have a new neutral at 0v and one line at 240v.

Sent from my Moto x4 using Tapatalk

[IanB]

I'm trying to understand all this.   How does the 208VAC work exactly?   You say it's phase to phase, that's like my North American Residential Standard Panel Input 240VAC split-phase, right?    240VAC from one 120VAC hot, and from the other 120VAC hot line coming in.   Phase to Neutral is 120.   With 208, you say Phase to neutral is 120.   So the other phase is 88VAC?

With three phase supplies the voltages don't add up like that. It is 120 V AC between each hot wire and the neutral, and 208 V AC between the two hot wires (don't ask why, it just is). This is very similar to the single phase supply where you have 120 V AC between each hot wire and neutral and 240 V AC between the two hot wires. The thing is that although the voltages are different, the equipment won't care. It will work with either supply.

[Spork Schivago]

...
In terms of how a power supply is designed and functions.. no, there really isn't a difference. You can throw around buzzwords and price tags all you like, the power supplies for those servers work just like any other.

You were the one who posted the datacenter pics with the three-phase, weren't you?

No.

I'm sorry, for some reason, I thought you were the one who posted that.

When I said fancy features, I meant HPE Power Discovery Services (PDS) combines the HPE Intelligent Power Distribution Unit (iPDU) and HPE Flex Slot Platinum Plus power supplies with HPE Insight Control software to create an automated, energy-aware network between IT systems and facilities.

Some simple firmware and a lot of marketing speak. Nothing to do with how the input is handled.

What I mean is with a normal desktop PC, we generally break the AC down to 12VDC, 5VDC, 3.3VDC, and -12VDC.    With servers like this one, we don't.   Also the equipment inside is generally better (higher quality) and is meant to run 24x7, whereas a desktop PSU really isn't most of the time.   Granted, there are some nice desktop PSUs that have higher quality capacitors and other components.   Ripple current is a bad thing, we agree on that I'm guessing.   With desktops, you can buy a cheap power supply that will kill your motherboard faster than shit because of ripple current.   With these server ones, you don't have to worry about that so much.   This PSU is "smart" in the sense that it's designed to be connected to a PDU that it communicates with.   Generally, desktop power supplies are plugged into surge protectors, not PDUs and aren't designed to communicate with that surge protector.

In the end, yes, they do the same thing.   They convert AC to DC.

I need true 240VAC 1-phase

Everyone can agree on this. And we can also all agree.. you have true 240VAC single-phase. It happens to have a centre tap making it split-phase distribution which is messing you (and the 'technicians' at HPE) up.

Whether we like it or not you need a 240-volt line to neutral power service.

No he doesn't. He needs a PDU capable of safely distributing his centre-tapped 240V phase, rather than a huge lump of iron hanging on his wall.

Okay, let's try looking at this at a different way, because I'm getting tired of just debating what I need versus how to actually hook up the transformer properly.   How many companies make RAM?   What?   Three maybe?   Or car batteries?   We'll go with car batteries.   There's two, maybe three companies that produce car batteries.   But how many different car batteries can you purchase?   I have no idea.   But it's a lot more than three, I know that.   There's die-hard, there's Duralast, there's NAPA, and a lot of those have different quality batteries as well, like NAPA Gold, or NAPA Silver, where Gold is supposed to be better.

I have a friend who worked in the automotive field for a long time and could give tours of one of the main manufacturers of the car batteries.   When you walked in, there was a giant glass display with all the different batteries they produced.   One of them was Duralast.   They used to call Duralast Durablast because they're kinda garbage.    This battery manufacturer made Duralast, but they also produced some really high quality batteries.   So, if they're making high quality batteries, why are Duralast so cheap?   It's because the company that's buying the Duralast is requesting that they don't use the high quality parts.   They want them as cheap as they can get 'em, so they have the battery company make them as cheap as they can get them.

Same is true with RAM.   Now, there's only a few companies who make RAM, even server RAM.   We have 2400 MHz load reduced DDR4 dual rank RAM in our servers, made by HPE.   It's pricey.   So I came up with the brilliant idea of maybe instead of purchasing the pricey HPE RAM, I would go and maybe purchase the cheaper server RAM produced by another company.   It'd work the same, probably be the same quality, just a different manufacturer.    Now this is where the trouble comes in.   Let's say I went ahead and purchased that other RAM and then all of a sudden, the motherboard's AC-DC converter circuit fries because of some manufacturing defect that has absolutely nothing to do with me.   The server is still under warranty, I call them up, do they cover the warranty?   No.    Why?   Because I wasn't running their "qualified" HPE RAM.

Even if HPE is wrong, and I can somehow power the PSUs with split-phase, they state that I need single-phase 240VAC.   If something were to happen, they would use that as an excuse not warrant the server faster than you could blink an eye!   I will say that today I got an invoice for one purchase that included some of the upgrades for one of the servers.   It was over 10,000$.    If I went and bought that stuff off of websites myself, it would have been over 30,000$.   That's just the upgrades for the one server.   I mention this for the sole reason that when HPE says we need 240VAC single-phase, I don't want to take any chances with them not covering their server's if something breaks because I didn't listen to their techs or went against what I was told to do.

This is not the first time HPE has said that we needed true 240VAC single-phase for the PSU's.   When our account executive contacted his HPE technicians pre-sale, to get the power advisory started, we gave them a list of everything that was going to be in the server, they came back with what choices we had for PSU's, and the only one on the list where these 1400 watt ones and they made it very clear that we needed the 240VAC and it wouldn't work with our split-phase.   We didn't like that, we asked if there wasn't any other options, why HPE didn't make a PSU for this server at 1400 watt that went to split-phase, we did conference calls, etc.   In the end, they said most people purchasing these power supplies have 3-phase.   Most commercial buildings don't have the residential wiring like we have.   Like, I think it was IanB stated, most people aren't running a real data center out of their basement in a residential zoning district.

At this point, I'd rather not debate anymore on whether or not I can go against what HPE techs and the people I called last night said and continue going in circles with you saying I need to send the PDU back and buy one that works with my electric and me saying I need the transformer.   That's not getting us anywhere.   Even if you feel it's a waste of money, I feel it is the correct move, and all I wanted was advice on what transformer to purchase, and then how to properly wire it up.   And yes, I am going to pay the licensed electrician lots of money to come watch me wire it up to make sure I don't make no mistakes.   I'm going to send the sketch into the city, I'm going to get the permit, I want to purchase the equipment through my VAR because I can get it much cheaper than the electrician charges, I don't know if he'd be okay with that or not though, he hasn't called me back.

But safety wise, rest assured, I'm not ignorant enough to try doing this myself.   I posted in the Beginners section because to me, this 240VAC 1-phase is new.   I have no problems running 240VAC split-phase or installing breakers, or wiring an outlet and running the wires to the breaker, up to code and all that, but this is out of my league, and is the main reason I came here, to try and understand it a bit better.

I appreciate the input you've given me and you definitely got me thinking, that's for sure.   I've learned a good bit since I started posting, which is wonderful, and for a bit, I enjoyed our debates, but now I just don't want to debate it anymore.   Thanks.

[Spork Schivago]

HP expects commercial power to be available in North America in two flavors of single phase: either 120 V AC ("low-line") or 208 V AC ("high-line"). The 208 V power would be derived from one leg of a three phase transformer and would be true 208-0 V single phase line to neutral.

240 and 480 phase to phase is also common commercial power.

208 is phase to phase, not phase to neutral. Phase to neutral is 120.

That is why there are two pole breakers on those PDU.

240 phase to phase would not be a problem.

I'm trying to understand all this.   How does the 208VAC work exactly?   You say it's phase to phase, that's like my North American Residential Standard Panel Input 240VAC split-phase, right?    240VAC from one 120VAC hot, and from the other 120VAC hot line coming in.   Phase to Neutral is 120.   With 208, you say Phase to neutral is 120.   So the other phase is 88VAC?

Each phase is 120VAC to the star point ('neutral'), 208VAC to each other. Three phases. As mentioned before, 'split phase' isn't really multiple phases: IT IS ONE PHASE with a centre tap.

And when a device can run off split-phase, does it combine the two phases internally to get the 240VAC or does half the circuit use 120VAC and the other half use 120VAC?

There are no halfs. Both hot conductors make for a single phase of 240VAC. That's all the load cares about. With the PDU it's a distribution concern - at loads it's irrelevant.

I'm not following how split-phase is really one phase with a centre tap.   Are you talking after it's ran to the device or while it's coming into the house?   Because I know if I take two breakers that are coming off what I call the first phase, and tie the hots together, I'm getting 120VAC, not 240VAC.    I need to tie a hot from one of the incoming lines to the hot from the other incoming line to get the 240VAC.

[Spork Schivago]

Change your PDUs for the type with double pole breakers and use your existing supply, or have an electrician (yes. really. please don't do it yourself.) install the transformer. Either will work.

It's not clear that there are any HPE PDUs with double pole breakers. The HPE literature divides the product range into two categories: NA/Japan which expects 200-208 V AC single phase, or INTL which expects 220-240 V AC single phase. In either case it is clear that this voltage is measured line to neutral, as is typically found in commercial premises.

OK, I stand corrected. The P9S13A does have a double pole breaker, as listed here: https://h20195.www2.hpe.com/v2/GetDocument.aspx?docname=a00002909enw

So it does appear that 240 V line to line or phase to phase should be acceptable for this particular PDU.

But then we're back to the power supplies being fed split-phase, aren't we?   It wasn't me who picked out the PDU or the PSUs.   And like I've stated, HPE could have been wrong during their power analysis, but after their power analysis there was one power supply that was available, and only one, the one we have.    And then when it came to a proper PDU, there was no PDUs available that would work with our PSUs and our split-phase, however, there were ones available that would work with 1-phase 240VAC or the 3-phase.   And eventually, we went for the 1-phase 240VAC out of the choices, because of the 3-phase being too much.

Back to the 3 phase system, I think that you are being told $50k to install is what I read? This seems very outrageous, having done this myself in my area. The 3 phase power lines were 1/4 mile away and the power company charged me a modest $300 to install the pole and transformer, however, I had to sign a 3 year contract with a minimal $25 charge for the service. Mind you, this was in 1980, so I could see a factor of 10 at least on that price, but still can't get to the $50k figure. You would still need to provide a distribution panel and do all of the wiring, which I did myself in 1980.

Hope this helps...

Yeah, 50k+ is what the electrician said it would cost us.   The actual electric company needed, I think around 2K, half up front, with a contract like you mentioned there.   And they needed the electrician to fill out some paperwork.   But that was just to get going.   After that, they'd send out some engineers and we'd be charged on stuff like the backhoe, and them running the wires, etc, etc.   A rough, overall estimate was over 50K, from the electrician, when all was said and done (which including the charges from the local power company).   We didn't get a second quote.   We just ruled it out all together.

But now, even if he lied because he didn't want to do it or something and someone came along and said we could get it for a couple grand, we'd have to change everything out.   All of our current rack mount equipment isn't designed for 3-phase.   I don't think we can do that though, we didn't make all purchases at once.   It took us years and years to buy things.   The rack was the start of the real business, but the other stuff I've been buying since 2005 and using it to make money.   It wasn't until we moved to the city that revenue started coming in real quick like and we had enough cash to purchase the rack, and then the switches, then the servers, the patch panel, the CAT6 shielded ethernet, the QFSP+ transceivers, etc.

My uncle passed away but was VP of the Science Division at one of the companies we're dealing with (the one that is insane about security).   My Aunt has a lot of money and my brothers and sisters have all asked her for some at one point in time.  She tried giving us some, but we refused because we believe we should earn our money, not accept it for free.   She wanted to help us though, and we told her about our new business and if she could spread the word, it would help generate some revenue.   Then shortly after, we had someone approach us at our house from that company where her now-deceased husband had worked.   He is a programmer and we were offered an opportunity to help with a project for income and we took it.   I think she had something to do with it.   The guy, we call him an employee, but he doesn't actually work for us.   He works for the other company.   He just helps us with stuff here and I'm what he calls the Team Leader.   I tell him what we need done, he'll work on it.   We use a VPN to connect to their network, but it's secure, where we have to use our cell phone and enter some code that changes every 30 seconds or we can't get in.   Two-Factor authentication.   But we also have these USB devices we plug into the PC to login and without the USB device, we cannot login at all.   We have to lock them up when we're not using them and we cannot keep them in any of the workstations.

[Monkeh]

The supply you have is single-phase. The winding on the transformer is centre tapped to create what is referred to as a split-phase installation. The centre tap is grounded and forms the neutral.

If you disconnected the centre tap entirely and connected one side of the winding to ground, you would have a single-phase 240VAC supply with a neutral. If you forget about using the neutral entirely, and forget about needing any ground reference at all, you still have a single-phase 240VAC supply, with no neutral. 120VAC only arrives because you're using only half of the winding by using the centre tap. You could get that without grounding the centre tap, too, you just can't call it a neutral.

If you refer back to the transformer diagram, it has two secondary windings - X1 to X2, and X3 to X4. X1 and X4 are your hot legs. X2 and X3 are the centre tap. If you were to connect those together, and then connect that point to ground, you would arrive at the same split-phase setup coming into your house. And still have 240VAC between X1 and X4, which will still run your power supplies just fine.

If you use the entire winding, by using both hot conductors, you have a 240VAC single-phase supply. It simply doesn't have one leg connected to ground - and that does not matter at all for the load. It is only a concern for the installation, which is why the PDUs need to be suited to it. And they make PDUs which are designed for this.

Allow me to shamelessly steal these off the internet:

[Spork Schivago]

But then we're back to the power supplies being fed split-phase, aren't we?   It wasn't me who picked out the PDU or the PSUs.   And like I've stated, HPE could have been wrong during their power analysis, but after their power analysis there was one power supply that was available, and only one, the one we have.    And then when it came to a proper PDU, there was no PDUs available that would work with our PSUs and our split-phase, however, there were ones available that would work with 1-phase 240VAC or the 3-phase.   And eventually, we went for the 1-phase 240VAC out of the choices, because of the 3-phase being too much.

Except that split phase in this context is not relevant. All you need care about is that it is a 240 V single phase supply. The P9S13A is designed and manufactured for the North American market and comes already fitted with a NEMA L6-30P plug that your electrician would have no problems with. It has 2-pole breakers which is what are needed for North American standards, and it can work with 200-240 V, which is compatible with the 240 V in your house. It is all good. Buying something that is not marked NA/JP is what has got you into trouble here.

A possible lesson learned here is not to rely on the vendor or salespeople to give technical advice. They are mainly interested in making the sale and taking your money. The best way to get advice is to engage an independent consultant with appropriate industry knowledge and experience, someone who will know how everything works and who is not just reading off sales brochures.

Well, with the lesson part....I can do what you said, but I'll explain something.   We recently placed a small order for 1,000 foot of Beldin CAT6 SFTP ethernet, a shielded CAT6A 48-port patch panel, a crimper designed for shielded ends, and a pack of 100 RJ45 plugs.   We called our Account Executive and told him that we needed shielded ethernet, CAT6, a shielded patch panel, a crimper, and the plugs, plus the punch down tool.   He reaches out to C2G (I think that's their name) and we do a conference call, but they don't sell CAT6A in SFTP, so he goes to his technicians and asks what's the most common shielded stuff people buy, what's the better quality stuff, not necessarily the most expensive.   They tell him, we do another conference call, and we agree on prices and the company we (our Account Executive, me, and the other company) setup a purchase.   They know exactly what I need, what I want, etc.    Long story short, we receive everything and the ends are just regular CAT6 RJ45 plugs.   They're not shielded.    So we call our Account Executive back and tell him we believe we've gotten the wrong part, and how we should have studied the order sheet a bit more carefully, but he says no, this isn't on us because we went through him and he went through the company.

It's on the company.   They had to pay return shipping, and they had to accept the ends, and they had to send us the proper ends, for the difference in price, of course.   While we were talking, our Account Executive said we want to avoid ordering from the companies directly for multiple reasons.   1) We don't get the price that he gets but more importantly, 2) If they send us the wrong part or the part that we don't need, it's on them, not on us.   He made that very clear there.

So, I can send back that PDU and tell him it's the wrong PDU and then say exactly what PDU I need, however, if it turns out the PDU you say is the one I want does not power the equipment I have (the mainframe, the servers, etc), that's all on me, and I don't think I can send that back.

Keep in mind, I would need two of those P9S13A's, and then the equipment to daisy chain them together.   We'd have to make sure the additional accessories we purchased with the PDU are compatible, we might need to order another set of those accessories.   Wiring up a NEMA L6-30P and a NEMA L6-30R is something I definitely don't need an electrician for.   That's something I've done more than once and can easily keep that up to code and wire it safely.   No problems there.   It's just the concern of going against what they all state what I need.   I have the right to dispute it and send it back, but if I'm wrong and it doesn't power on the mainframe or the servers, then I might very well be out a lot of money because I might not be able to send them back, and I might have to end up buying the same PDU they said I needed again, but this time, probably not as cheap (they bid), and we're talking more time wasted because I'll be back here, asking again about the transformer, etc.

With that in mind, if you were me, would you take the chance and send the PDU back and order the other two, plus the additional equipment to get it running?   Or would you just purchase the transformer and new breaker panel?

[Spork Schivago]

The supply you have is single-phase. The winding on the transformer is centre tapped to create what is referred to as a split-phase installation. The centre tap is grounded and forms the neutral.

If you disconnected the centre tap entirely and connected one side of the winding to ground, you would have a single-phase 240VAC supply with a neutral. If you forget about using the neutral entirely, and forget about needing any ground reference at all, you still have a single-phase 240VAC supply, with no neutral. 120VAC only arrives because you're using only half of the winding by using the centre tap. You could get that without grounding the centre tap, too, you just can't call it a neutral.

If you refer back to the transformer diagram, it has two secondary windings - X1 to X2, and X3 to X4. X1 and X4 are your hot legs. X2 and X3 are the centre tap. If you were to connect those together, and then connect that point to ground, you would arrive at the same split-phase setup coming into your house. And still have 240VAC between X1 and X4, which will still run your power supplies just fine.

If you use the entire winding, by using both hot conductors, you have a 240VAC single-phase supply. It simply doesn't have one leg connected to ground - and that does not matter at all for the load. It is only a concern for the installation, which is why the PDUs need to be suited to it. And they make PDUs which are designed for this.

Allow me to shamelessly steal these off the internet:

Wow!   I get it!   I actually understand how it works now!!!!!   I cannot thank you enough for explaining that!   You have no idea how long I've tried to wrap my head around the AC system coming into the house.   Just to make sure I'm following, in your second sentence, when you say the winding on the transformer is centre tapped....you're talking about the transformer on the pole, right?   I know that probably makes me sound like an idiot, but I just want to make sure I really do understand.   Those images helped a lot too.   But you explaining the x1 and x4 and x2 and x3, that's when it really hit.   So it's the number of winds on the transformers that determine the voltages then, isn't it?

Is it a magnetic field that transfers the energy from the primary to the secondary side of the transformers?   It'd have to be, I'd think, right?   Otherwise, it'd be like two windings in series and it'd affect the input voltage supply.   By that, I mean, instead of expecting 120VAC, it might expect 360VAC, if the windings where physically connected to each other.

[Monkeh]

Wow!   I get it!   I actually understand how it works now!!!!!   I cannot thank you enough for explaining that!   You have no idea how long I've tried to wrap my head around the AC system coming into the house.   Just to make sure I'm following, in your second sentence, when you say the winding on the transformer is centre tapped....you're talking about the transformer on the pole, right?   I know that probably makes me sound like an idiot, but I just want to make sure I really do understand.   Those images helped a lot too.   But you explaining the x1 and x4 and x2 and x3, that's when it really hit.   So it's the number of winds on the transformers that determine the voltages then, isn't it?

Bingo. The transformer on the pole is indeed centre tapped (or two windings with the ends connected like the small one you're looking at - functionally equivalent for our purposes). Number of turns around the core determines the voltage. Centre tap it and you effectively cut the number of turns in half.

Is it a magnetic field that transfers the energy from the primary to the secondary side of the transformers?   It'd have to be, I'd think, right?

Yes. Transformers transfer energy via magnetic field. In the case of a single-phase system, that is one single magnetic field rising and falling - that's why centre tapped systems are still single phase.

So with all that out the way.. you have 240VAC single phase. Neither conductor is directly connected to ground, which is a critical point to take care of with distribution. For loads, it's irrelevant.

[Spork Schivago]

I was pointed to this datasheet on page 13: https://cc.cnetcontent.com/vcs/hp-ent/inline-content/SI/6/2/62A6FA74BB1B193CE4C7ABB42D42E37228B9C4A7_source.PDF

This is what they quoted:

Code: [Select]

Input Voltage        Low Line - Rated: 100V - 127V; Min 90V to Max 132V
                     High Line - Rated: 200 - 240V; Min 180V to Max 264V
                     (model 720620-B21 and 720482-B21 supports High Line AC input only)
                     High Line - Rated: 200 - 277VAC; Min 180VAC to Max 305VAC (model 720484-B21 only)
Mine are the 720620-B21.   So do I still insist on those two P9S13A's?

[Monkeh]

I was pointed to this datasheet on page 13: https://cc.cnetcontent.com/vcs/hp-ent/inline-content/SI/6/2/62A6FA74BB1B193CE4C7ABB42D42E37228B9C4A7_source.PDF

This is what they quoted:

Code: [Select]

Input Voltage        Low Line - Rated: 100V - 127V; Min 90V to Max 132V
                     High Line - Rated: 200 - 240V; Min 180V to Max 264V
                     (model 720620-B21 and 720482-B21 supports High Line AC input only)
                     High Line - Rated: 200 - 277VAC; Min 180VAC to Max 305VAC (model 720484-B21 only)
Mine are the 720620-B21.   So do I still insist on those two P9S13A's?

Well, yes, you need 240V. The P9S13A will allow you to use your existing 240V supply.

[Richard Crowley]

I'm trying to understand all this.   How does the 208VAC work exactly?   You say it's phase to phase, that's like my North American Residential Standard Panel Input 240VAC split-phase, right?    240VAC from one 120VAC hot, and from the other 120VAC hot line coming in.   Phase to Neutral is 120. 

Your 120-0-120 split-phases are 180 degrees apart. So when you take "phase-to-phase" you get 120V + 120V = 240V

With 208, you say Phase to neutral is 120.   So the other phase is 88VAC?

Three-phase power is not 180 degrees apart.  The phases are 120 degrees apart 

There is no "other phase" in 3-phase. There are THREE EQUAL phases around the 360 degree phase circle.

Note that 208V is 86% of 240V and the sine of 120 degrees is 0.86  Not a coincidence.

And when a device can run off split-phase, does it combine the two phases internally to get the 240VAC

If by "split-phase" you mean 120-0-120 domestic mains power service, the two "phases" are 240V apart BY DEFINITION.
By connecting from one phase over to the other (ignoring the "neutral") then you have 240V.
You can call that "combining" if you want, but it won't make any sense to an electrician (or electrical engineer).

or does half the circuit use 120VAC and the other half use 120VAC?

240V domestic appliances (water heater, oven, clothes dryer, etc.) have big resistive heating elements that operate directly on 240V
THey make no reference to the "neutral", and there is no "one half" or "other half".
Many older installations didn't even have a neutral wire.  Just L1, L2, and ground.

[Spork Schivago]

I'm trying to understand all this.   How does the 208VAC work exactly?   You say it's phase to phase, that's like my North American Residential Standard Panel Input 240VAC split-phase, right?    240VAC from one 120VAC hot, and from the other 120VAC hot line coming in.   Phase to Neutral is 120. 

Your 120-0-120 split-phases are 180 degrees apart. So when you take "phase-to-phase" you get 120V + 120V = 240V

With 208, you say Phase to neutral is 120.   So the other phase is 88VAC?

Three-phase power is not 180 degrees apart.  The phases are 120 degrees apart 

There is no "other phase" in 3-phase. There are THREE EQUAL phases around the 360 degree phase circle.

Note that 208V is 86% of 240V and the sine of 120 degrees is 0.86  Not a coincidence.

And when a device can run off split-phase, does it combine the two phases internally to get the 240VAC

If by "split-phase" you mean 120-0-120 domestic mains power service, the two "phases" are 240V apart BY DEFINITION.
By connecting from one phase over to the other (ignoring the "neutral") then you have 240V.
You can call that "combining" if you want, but it won't make any sense to an electrician (or electrical engineer).

or does half the circuit use 120VAC and the other half use 120VAC?

240V domestic appliances (water heater, oven, clothes dryer, etc.) have big resistive heating elements that operate directly on 240V
THey make no reference to the "neutral", and there is no "one half" or "other half".
Many older installations didn't even have a neutral wire.  Just L1, L2, and ground.

Okay, so, for example, my BGA rework station that runs of 120-0-120 from the mains, the heating elements have only two connections, one going in, one coming out.   They operate directly on 240VAC.   Somewhere, in the circuit, before the electricity reaches those heating elements, there must be a connection where the two phases connect to produce that 240VAC, right?

Here, I have always looked at Neutral and Ground as the same, because in my breaker panel, they are.   I take it that's not correct though, I should look at them differently.

If I were to simply rewire the BGA rework station to have 240VAC going down the L1, ground going down the Earth, and Neutral going down the N, then that would be bad, wouldn't it?   Because eventually, L1 (240VAC) would be connecting directly to ground.

[IanB]

Okay, so, for example, my BGA rework station that runs of 120-0-120 from the mains, the heating elements have only two connections, one going in, one coming out.   They operate directly on 240VAC.   Somewhere, in the circuit, before the electricity reaches those heating elements, there must be a connection where the two phases connect to produce that 240VAC, right?

Here, I have always looked at Neutral and Ground as the same, because in my breaker panel, they are.   I take it that's not correct though, I should look at them differently.

If I were to simply rewire the BGA rework station to have 240VAC going down the L1, ground going down the Earth, and Neutral going down the N, then that would be bad, wouldn't it?   Because eventually, L1 (240VAC) would be connecting directly to ground.

Let me give you an example. I have a 240 V electric kettle in my kitchen that I have imported from England (I like tea, and I don't want to wait too long for the water to boil).

In the UK, the kettle is wired to a 240 V plug with live, neutral and earth. There is 240 V AC between live and neutral and earth is for safety. It happens that the neutral wire is "neutral", but the kettle doesn't know this. The kettle is a European model that may be sold in many local European markets, and they may not all have the same electrical supply arrangements that the UK has. But I digress...

Here in the USA I have cut off the UK plug and replaced it with a NEMA 6-20 plug (240 V single phase plus ground). In the 6-20 plug I have wired "L" to one pole (L1), "N" to the other pole (L2), and "E" to the ground pin. I plug this into a 6-20 wall socket and I enjoy rapid boiling water from the 3 kW heating element.

The kettle doesn't know that one of the wires isn't neutral, and it doesn't matter because the insulation between the heating element and the rest of the kettle must have been breakdown tested at high voltage to obtain appropriate safety certifications. Some countries in Europe may have a supply where both wires are live just as in North America.

[Richard Crowley]

Okay, so, for example, my BGA rework station that runs of 120-0-120 from the mains, the heating elements have only two connections, one going in, one coming out.   They operate directly on 240VAC.   Somewhere, in the circuit, before the electricity reaches those heating elements, there must be a connection where the two phases connect to produce that 240VAC, right?

No. You may be over-analyzing this.  The first "phase" (L1) goes to one side of the 240V heating element, and the other "phase" (L2) goes to the other side of the heating element.  Simple as that.
The phases "connect" THROUGH the heating element.

Here, I have always looked at Neutral and Ground as the same, because in my breaker panel, they are.   I take it that's not correct though, I should look at them differently.

That is completely true. But it has nothing to do with getting 240V from 120-0-120 split-phase.

If I were to simply rewire the BGA rework station to have 240VAC going down the L1, ground going down the Earth, and Neutral going down the N, then that would be bad, wouldn't it?   Because eventually, L1 (240VAC) would be connecting directly to ground.

No. 240V exists only BETWEEN L1 and L2 (the two "phases" of "split-phase".)
There is no Neutral here.  And Ground is only the safety path to prevent you from being electrocuted, or from setting your house on fire.

[james_s]

It may be easier to visualize this as a transformer with a center tapped secondary, which is exactly what this is. Even simpler you can ignore the center tap because if you want 240V the center tap could be floating or not exist and it would look the same to a 240V load. Consider a single secondary producing 240V, you could ground one end of it to have a Euro-style 240V service, or you could leave it completely floating and have a US style 240V feed. The only difference is that in a real US installation there is a center tap which is tied to ground but that is only relevant when you want to draw 120V from one end or the other to neutral/ground.

[C]

If you split a apple PIE do you get two Pies?
So how do you get two phases?

AC = alternating current

An alternator is an electrical generator that converts mechanical energy to electrical energy in the form of alternating current. For reasons of cost and simplicity, most alternators use a rotating magnetic field with a stationary armature.[

https://en.wikipedia.org/wiki/Alternator

The hands on a analog clock rotate.
Think of the center of clock as 0 Volts
Max Positive Volts is 12 o'clock.
Max Negative Volts is 6 o'clock.
This makes 3 o'clock & 9 o'clock also 0 Volts as Volts is vertical dimension.

Single phase states you have one hand on clock like hour hand.

60 Hz states that the hand is completing 60 rotations a second.

now when you look at the volt rating is states
RMS

RMS = Root mean square
so if you see "240 Volt RMS"  the peak voltage is 1.414 x 240.
So the 12 o'clock position the max positive = 339.36 volts.

You use the sin table to compute a value based on rotation.

With one end at center you 0 volt connection.
As the hand rotates the other end goes from 12 o'clock around to 6 o'clock and back to 12 o'clock.

So single phase 240 volts is like hour hand rotating.
Going from 9 o'clock (0 volts) to 12 o'clock ( +339.36 volts) and around to 6 o'clock (-339.36 volts) and back to 9 o'clock.
Note that the hand is over 1/2 of the clock so the clock face is 678.72 volts in hight.

 Split-phase is extending the hour hand to other side of circle. When one end of the hand is at 12 o'clock the outer end is at 6 o'clock.
You have three connections. The two hand tips and the center.
Using full clock face you have the clock face 339.36 volts in hight.
Max Positive (12 o'clock) = +169.68 volts
169.68 / 1.414 = 120 volts RMS

Three phase is 3 hour hands 60 degrees apart.

The center of the clock face is the Neutral connecting in above.

The Hour hand tip(s) are the other connection.

Monkeh posted a plot of the voltage vs time which is also a plot of voltage vs rotation.

Have you used a two cell flash light?
The light connects to the two ends of the batteries in series.
Split-phase is adding a connection between the two batteries.

Get out your pencil and paper and make some drawings.

C

 

[Spork Schivago]

Okay, so, for example, my BGA rework station that runs of 120-0-120 from the mains, the heating elements have only two connections, one going in, one coming out.   They operate directly on 240VAC.   Somewhere, in the circuit, before the electricity reaches those heating elements, there must be a connection where the two phases connect to produce that 240VAC, right?

No. You may be over-analyzing this.  The first "phase" (L1) goes to one side of the 240V heating element, and the other "phase" (L2) goes to the other side of the heating element.  Simple as that.
The phases "connect" THROUGH the heating element.

Here, I have always looked at Neutral and Ground as the same, because in my breaker panel, they are.   I take it that's not correct though, I should look at them differently.

That is completely true. But it has nothing to do with getting 240V from 120-0-120 split-phase.

If I were to simply rewire the BGA rework station to have 240VAC going down the L1, ground going down the Earth, and Neutral going down the N, then that would be bad, wouldn't it?   Because eventually, L1 (240VAC) would be connecting directly to ground.

No. 240V exists only BETWEEN L1 and L2 (the two "phases" of "split-phase".)
There is no Neutral here.  And Ground is only the safety path to prevent you from being electrocuted, or from setting your house on fire.

I'm trying to learn, that's why I asked about the Neutral and Ground.   So if L1 and L2 are going into the heating element, where is the completed path?   Where does it go back to Ground?   Electrons are attracted to electrons of the opposite charge, right?   So if I feed a heating element just two 120VAC sources, I wouldn't think it'd heat at all....that's where I'm getting confused here.   I was always taught you need a complete circuit, and without it, you don't get a working circuit.   Each load draws current and has a voltage drop.  By the time we get to ground, that voltage is 0VDC.   But without that ground, where do the electrons go?   Just L1's electrons fly down L2's conducting material and L2's electrons fly down L1's conducting material, even though they're of the same charge?   Or is it because they're not in phase, this works?   If L1 is out of phase with L2, then L1 would be the opposite charge of L2?

[Spork Schivago]

If you split a apple PIE do you get two Pies?
So how do you get two phases?

AC = alternating current

An alternator is an electrical generator that converts mechanical energy to electrical energy in the form of alternating current. For reasons of cost and simplicity, most alternators use a rotating magnetic field with a stationary armature.[

https://en.wikipedia.org/wiki/Alternator

The hands on a analog clock rotate.
Think of the center of clock as 0 Volts
Max Positive Volts is 12 o'clock.
Max Negative Volts is 6 o'clock.
This makes 3 o'clock & 9 o'clock also 0 Volts as Volts is vertical dimension.

Single phase states you have one hand on clock like hour hand.

60 Hz states that the hand is completing 60 rotations a second.

now when you look at the volt rating is states
RMS

RMS = Root mean square
so if you see "240 Volt RMS"  the peak voltage is 1.414 x 240.
So the 12 o'clock position the max positive = 339.36 volts.

You use the sin table to compute a value based on rotation.

With one end at center you 0 volt connection.
As the hand rotates the other end goes from 12 o'clock around to 6 o'clock and back to 12 o'clock.

So single phase 240 volts is like hour hand rotating.
Going from 9 o'clock (0 volts) to 12 o'clock ( +339.36 volts) and around to 6 o'clock (-339.36 volts) and back to 9 o'clock.
Note that the hand is over 1/2 of the clock so the clock face is 678.72 volts in hight.

 Split-phase is extending the hour hand to other side of circle. When one end of the hand is at 12 o'clock the outer end is at 6 o'clock.
You have three connections. The two hand tips and the center.
Using full clock face you have the clock face 339.36 volts in hight.
Max Positive (12 o'clock) = +169.68 volts
169.68 / 1.414 = 120 volts RMS

Three phase is 3 hour hands 60 degrees apart.

The center of the clock face is the Neutral connecting in above.

The Hour hand tip(s) are the other connection.

Monkeh posted a plot of the voltage vs time which is also a plot of voltage vs rotation.

Have you used a two cell flash light?
The light connects to the two ends of the batteries in series.
Split-phase is adding a connection between the two batteries.

Get out your pencil and paper and make some drawings.

C

With those batteries though, that connection between them has to return back to either the bottom cell or the top cell to complete the circuit, otherwise, the electrons have no place to go.   That's what I don't understand with the AC, unless I was right about the L1 and L2 being opposite charges, one being +120VAC, the other being -120VAC, and the +120VAC passes through the heating element to the -120VAC, providing a voltage drop of 240VAC total over the heating element....is that correct?

[james_s]

L1 and L2 have 240V across between them, forget about ground, ground is a relative term. With AC the current reverses direction every half cycle, so half the cycle you have current flowing out of L1 and into L2, then the other half cycle it flows out of L2 into L1, there's your complete circuit. If you wanted you could call either L1 or L2 "ground", and you'd be able to connect it to earth ground *except* for the fact that the center tap is already connected to ground so doing this would create a direct short across one half of the transformer secondary.

[james_s]

With those batteries though, that connection between them has to return back to either the bottom cell or the top cell to complete the circuit, otherwise, the electrons have no place to go.   That's what I don't understand with the AC, unless I was right about the L1 and L2 being opposite charges, one being +120VAC, the other being -120VAC, and the +120VAC passes through the heating element to the -120VAC, providing a voltage drop of 240VAC total over the heating element....is that correct?

There's no such thing as +AC and -AC, the polarity is changing 120 times a second. If you were to freeze time at the peak of one cycle then yes you'd see +170V on one of the wires and -170V on the other, but the next half cycle that will reverse. In reality the value is not suddenly flipping (square wave) but is a sine wave, so the RMS value is 120/240 for a peak of 170/340.

[Gregg]

As previously drawn but maybe looking at the power from a different view may help.

The electric utility company has a transformer somewhere near your house; it is wired as shown in the diagram (in the USA).

As you can see the secondary winding is continuous and the output voltage of L1 and L2 are in proportion to the much higher voltage of the primary by the ratio of turns.  In the US it is 240 Volts nominal for most residential services.

The center tap of the secondary is brought out and called Neutral.  It is grounded to the earth near the transformer.  It is called Neutral because it is grounded and because the voltage between the neutral and either L1 or L2 is half the voltage between them, in this case 120 volts to either L1 or L2.  The neutral conductor from the utility carries any imbalance of the two other lines.  For instance, if you had 30 amps load on the 120volt side from L1 to neutral and 20 amps load on the other side from L2 to neutral, the neutral conductor would carry the 10 amp difference back to the transformer.

After the meter at the main disconnect panel (200 amp 2 pole 240v for this discussion) the neutral and ground are bonded together.  This is the only place they should be connected in your house.  The ground wires going to things in your house should not carry any current; they are there for safety reasons such as either L1 or L2 shorted to ground; then the ground wire should be able to carry the fault current long enough for the breaker to trip.

Ground and Neutral are NOT the same thing even though they are connected at the main panel.  Power doesn’t return to ground, it returns to the transformer. 

The potential between Neutral and Ground is very low, depending on resistance of the wiring, current in the neutral conductor and anything that may be leaking to ground (like Y capacitors, but we aren’t going there in this discussion).

[Richard Crowley]

So if L1 and L2 are going into the heating element, where is the completed path?

The path is:  From L1,  through the load (heating element) and returns to L2

Where does it go back to Ground? 

Repeating: 240V exists between L1 and L2.  The current doesn't "go back go ground" (or neutral).

So if I feed a heating element just two 120VAC sources, I wouldn't think it'd heat at all....that's where I'm getting confused here.

What you apparently don't understand is that 120-0-120 ("split-phase") is NOT "just two 120VAC sources."  You have 240VAC coming into your house between L1 and L2 (the two "phases"). It makes absolutely no difference whether L1 is connected to ground, or L2 is connected to ground, or if some point halfway between is connected to ground.  GROUND IS IRRELEVANT.   

If you insist on viewing the L1 and L2 voltages from the perspective of neutral/ground (at the center-tap) you should note that they are 180 degrees out of phase (opposite phases).  You are correct, if L1 and L2 were of similar phase, then there would be no voltage differential between L1 and L2, and no current would flow through your load.

I was always taught you need a complete circuit, and without it, you don't get a working circuit.   Each load draws current and has a voltage drop.  By the time we get to ground, that voltage is 0VDC.   But without that ground, where do the electrons go? 

Current flow does NOT depend on "ground".  Else your cell phone (or flashlight or automobile) would be unable to operate with no connection to "ground".

Just L1's electrons fly down L2's conducting material and L2's electrons fly down L1's conducting material, even though they're of the same charge?   Or is it because they're not in phase, this works?   If L1 is out of phase with L2, then L1 would be the opposite charge of L2?

You are beginning to get it.  L1 and L2 are of opposite "phases" when viewed from that center-tap ground/neutral.  The 240 volts coming into your house is split in half in order to provide 120V branch circuits to power your domestic appliances, lights, etc. 

But you have 240VAC coming into your house.  Your problem here is that it is center-tapped and grounded. But your PDUs want 240-0 (one side grounded, aka. "single-phase"), not 120-0-120 (center-tap grounded, aka "split-phase")  That is why you need a transformer to allow you to ground one side of the 240V to create "single-phase".

You do not have two identical 120V phases coming into your house.  You have 240V which happens to be center-tapped and grounded.  And electricians call it "split" or "two" phases.

[Spork Schivago]

L1 and L2 have 240V across between them, forget about ground, ground is a relative term. With AC the current reverses direction every half cycle, so half the cycle you have current flowing out of L1 and into L2, then the other half cycle it flows out of L2 into L1, there's your complete circuit. If you wanted you could call either L1 or L2 "ground", and you'd be able to connect it to earth ground *except* for the fact that the center tap is already connected to ground so doing this would create a direct short across one half of the transformer secondary.

That's what I've been missing.   I wasn't talking about the transformer here, I was talking about 120-0-120 split-phase that comes into the house, and trying to see how it's equivalent to 240VAC over in Europe.   Because over there, they'll have L1 and then Neutral hooked to the heating elements, which would still give the 240VAC.   I think I understand now fully how the AC works.

Now, why would connecting earth ground to a 240VAC source that comes from 120-0-120VAC USA split-phase or whatever you want to call it cause a short there?   It's because L1 and L2 are reciprocals of each other, right?  When one is 120VAC, the other is -120VAC.   When one is 75VAC, the other is -75VAC.   When one is zero, the other is zero.   If we added a ground, when either where anything other than 0VAC, we'd have our direct connection to ground, which would be horrible.   Am I finally understanding this?

[Spork Schivago]

With those batteries though, that connection between them has to return back to either the bottom cell or the top cell to complete the circuit, otherwise, the electrons have no place to go.   That's what I don't understand with the AC, unless I was right about the L1 and L2 being opposite charges, one being +120VAC, the other being -120VAC, and the +120VAC passes through the heating element to the -120VAC, providing a voltage drop of 240VAC total over the heating element....is that correct?

There's no such thing as +AC and -AC, the polarity is changing 120 times a second. If you were to freeze time at the peak of one cycle then yes you'd see +170V on one of the wires and -170V on the other, but the next half cycle that will reverse. In reality the value is not suddenly flipping (square wave) but is a sine wave, so the RMS value is 120/240 for a peak of 170/340.

Yes, I realize it's changing so fast we can't see it, but that doesn't really mean it's not there.   I think I have a good understanding of it now, except  for the RMS.   I have a true RMS DMM, so when I measure the voltage from my receptacles, I see 120VAC.   I don't see 170VAC.   When the sine wave is at the peak, you're saying for 120VAC, it's really 170VAC +/- ?   And for 240VAC, it's really 340VAC +/-?   RMS = Root Mean Square.   The RMS value is 120/240, as you say...even my old analog volt meter that isn't true RMS measures it at 120VAC though.... so I'm still missing some pieces to this, but I'm getting there.   I don't understand why we use the RMS and not just the peak value when measuring or talking about the voltage sources.   Why use the RMS value?   Why not just call it 170VAC or 340VAC?

With the European 240VAC, don't they generally have 240VAC going down L1 and Neutral to Neutral, Ground to Ground (where Neutral would be connected to Ground, like in my breaker panel)?   If so, wouldn't they receive a short if they tried hooking my BGA rework station (which is wired with L1 = 120VAC, L2 = 120VAC, N = Neutral, E = Earth) directly into their outlets, just by changing the NEMA L6-30P I wired to the end of it?   We still have the sine wave, where it's going from positive to negative for one wave cycle right?   But now, because they're using 1-phase 240VAC, they don't have the L1 and L2, where the AC goes into L1, then back into L2, and so on and so forth...the heating elements would be wired up so 240VAC was feeding directly through the heating element and then to ground.   I guess that wouldn't cause a short though, would it?   The heating element would still be the load and would still have a voltage drop of 240VAC.   So nothing would change there I guess....hrmm.

I'm trying to think if there's any cases where just switching the plug on one of our devices that is made for our 240VAC to fit into their receptacles over there would cause damage.   I know we can do it here, most of the time, but does it usually work the same over there?

[Spork Schivago]

As previously drawn but maybe looking at the power from a different view may help.

The electric utility company has a transformer somewhere near your house; it is wired as shown in the diagram (in the USA).

As you can see the secondary winding is continuous and the output voltage of L1 and L2 are in proportion to the much higher voltage of the primary by the ratio of turns.  In the US it is 240 Volts nominal for most residential services.

The center tap of the secondary is brought out and called Neutral.  It is grounded to the earth near the transformer.  It is called Neutral because it is grounded and because the voltage between the neutral and either L1 or L2 is half the voltage between them, in this case 120 volts to either L1 or L2.  The neutral conductor from the utility carries any imbalance of the two other lines.  For instance, if you had 30 amps load on the 120volt side from L1 to neutral and 20 amps load on the other side from L2 to neutral, the neutral conductor would carry the 10 amp difference back to the transformer.

After the meter at the main disconnect panel (200 amp 2 pole 240v for this discussion) the neutral and ground are bonded together.  This is the only place they should be connected in your house.  The ground wires going to things in your house should not carry any current; they are there for safety reasons such as either L1 or L2 shorted to ground; then the ground wire should be able to carry the fault current long enough for the breaker to trip.

Ground and Neutral are NOT the same thing even though they are connected at the main panel.  Power doesn’t return to ground, it returns to the transformer. 

The potential between Neutral and Ground is very low, depending on resistance of the wiring, current in the neutral conductor and anything that may be leaking to ground (like Y capacitors, but we aren’t going there in this discussion).

We gotta back up the train here a bit.   I understand the purpose of the neutral and ground in the house.   If we have a short, we want that current and voltage to go to the path of least resistance, hopefully back to the breaker, to trip it.

The transformer at the pole though....you said, "For instance, if you had 30 amps load on the 120volt side from L1 to neutral and 20 amps load on the other side from L2 to neutral, the neutral conductor would carry the 10 amp difference back to the transformer."

Where are these loads coming from?    Some place in the transformer, or in the house?   Why would there ever be an excess of current?   A 60 watt bulb will always draw 60 watt, even if you have it hooked to a 200-amp breaker.   So how could you ever have an excess of current?   Even if you were to directly wire hot to neutral or hot to ground, if neutral and ground are at 0V, wouldn't there be an instant volt drop where they connected and a lot of heat generated?   I had an old camaro and the ignition went bad.   I had to hot wire it.   I'd use the fuse panel.   I'd hook to a 12V source, then use a wire to tie into the fuse for the Ignition.   Then I'd hook into the 12V source and tie into the starter, but just long enough to get running.   One day, I was a little careless and grounded that 12V source.   The wire evaporated in my hand and left a white indent.   At first it didn't hurt, then it hurt real bad.   But there wasn't no excess current that just traveled safely back to the cells in the battery.   Wouldn't an excess current be called a short?

Also, how come our neutrals and grounds in the house are tied together?   Why can we not have it like the transformers on the poles where neutral is seperate from ground?   Actually, I probably could, couldn't I?   Outside, there's a grounding wire that's buried in the earth that hooks to the panel.   If I separated the ground and neutral buss-bars in the breaker panel, and made sure my ground buss-bar went to the grounding wire outside, and the neutral went back to the pole, I'd essentially have the same setup as the pole.   Someone in this thread mentioned in their house they'd never have the ground tied to the neutral.   But in every home I've seen, this is how it's always setup.   Is there any dangers to doing what I just described?

[IanB]

With the European 240VAC, don't they generally have 240VAC going down L1 and Neutral to Neutral, Ground to Ground (where Neutral would be connected to Ground, like in my breaker panel)?   If so, wouldn't they receive a short if they tried hooking my BGA rework station (which is wired with L1 = 120VAC, L2 = 120VAC, N = Neutral, E = Earth) directly into their outlets, just by changing the NEMA L6-30P I wired to the end of it?

You have listed four wires (L1, L2, N, E), but in the L6-30P there are only supposed to be three wires (L1, L2, E). There is no neutral.

Your BGA rework station is only supposed to have three wires too. In the European outlet there are two wires carrying 240 V between them, and a third wire for safety ground. In the USA the L6-30 receptacle has two wires carrying 240 V between them and a third wire for safety ground. So the situation is really the same in Europe as it is here from an electrical perspective. It is only the safety arrangements that differ.

We call a wire "hot" or "live" because it is effectively hot and will hurt you if you touch it. We call a wire neutral because--theoretically--it won't hurt you if you touch it (but don't rely on this). There is no difference between live and neutral as far as carrying electric current is concerned, there is only a difference with regard to safety and protection arrangements.

[Spork Schivago]

So if L1 and L2 are going into the heating element, where is the completed path?

The path is:  From L1,  through the load (heating element) and returns to L2

Where does it go back to Ground? 

Repeating: 240V exists between L1 and L2.  The current doesn't "go back go ground" (or neutral).

So if I feed a heating element just two 120VAC sources, I wouldn't think it'd heat at all....that's where I'm getting confused here.

What you apparently don't understand is that 120-0-120 ("split-phase") is NOT "just two 120VAC sources."  You have 240VAC coming into your house between L1 and L2 (the two "phases"). It makes absolutely no difference whether L1 is connected to ground, or L2 is connected to ground, or if some point halfway between is connected to ground.  GROUND IS IRRELEVANT.   

If you insist on viewing the L1 and L2 voltages from the perspective of neutral/ground (at the center-tap) you should note that they are 180 degrees out of phase (opposite phases).  You are correct, if L1 and L2 were of similar phase, then there would be no voltage differential between L1 and L2, and no current would flow through your load.

I was always taught you need a complete circuit, and without it, you don't get a working circuit.   Each load draws current and has a voltage drop.  By the time we get to ground, that voltage is 0VDC.   But without that ground, where do the electrons go? 

Current flow does NOT depend on "ground".  Else your cell phone (or flashlight or automobile) would be unable to operate with no connection to "ground".

Just L1's electrons fly down L2's conducting material and L2's electrons fly down L1's conducting material, even though they're of the same charge?   Or is it because they're not in phase, this works?   If L1 is out of phase with L2, then L1 would be the opposite charge of L2?

You are beginning to get it.  L1 and L2 are of opposite "phases" when viewed from that center-tap ground/neutral.  The 240 volts coming into your house is split in half in order to provide 120V branch circuits to power your domestic appliances, lights, etc. 

But you have 240VAC coming into your house.  Your problem here is that it is center-tapped and grounded. But your PDUs want 240-0 (one side grounded, aka. "single-phase"), not 120-0-120 (center-tap grounded, aka "split-phase")  That is why you need a transformer to allow you to ground one side of the 240V to create "single-phase".

You do not have two identical 120V phases coming into your house.  You have 240V which happens to be center-tapped and grounded.  And electricians call it "split" or "two" phases.

I had temporarily moved away from the transformer for the PDU.   I understand completely why I need a transformer for the PDU and why I could never power it with just a double pole breaker hooked to my panel.   What I wasn't getting (but am now) is that the current for AC flows forwards and backwards, not just forwards like DC.   I had said early on I understood DC fairly well, it was the AC I struggled with, but now I feel I have a pretty good grasp of how the 240VAC works in the USA.   Still not sure about 1-phase 240VAC that is used in other parts of the world, or that would be used with my transformer.    Because we don't have an L1 and L2, because the 240VAC is on the same phase, where do the electrons go if they're not hooked to a neutral or ground to complete the circuit?    Somehow they have to make it back to the breaker, correct?   I use the word ground, but all I mean is a completed circuit.   I know and understand that a completed circuit doesn't need a ground or a voltage potential of 0V.   I could technically power a circuit where the supply is 24V and the return is 12V.   So long as the return is at a lower voltage potential than the supply, we can have the electrons moving.

Using the water analogy that everyone seems to like to use, we have our "pump" (the transformer I'd buy for the PDU, for example).   The "water" (electrons) flow out of L1 into the PDU.   But then what?   They need to make it back to the "pump" (transformer) somehow.    I know you say ground / neutral is irrelevant, but in this case, I cannot imagine how those pesky little buggers would make it back to complete the circuit without using one of those other wires that are at 0V potential.    The components inside the PDU would be the loads and by the time the current / electricity had passed through the entire circuit and was ready to leave the PDU, it surely wouldn't just be traveling up the L1 wire again, would it?   We'd have to use one of the additional neutral / ground wires in that instance.   Just like if we're dealing with 120VAC receptacles.   We cannot just hook up the hot wire.   That wouldn't do diddly squat.   We'd still have to hook up the neutral so the electrons could make it back to the panel.

With the 120-0-120, I understand how it works now.   I also understand why if I were to not use a double pole breaker but tried wiring up a NEMA L6-30R using a 30-amp single pole breaker in slot 1 and slot 2 (opposites sides of the panel), it wouldn't work.   I'd have 120VAC, not 240VAC.

[IanB]

Also, how come our neutrals and grounds in the house are tied together?   Why can we not have it like the transformers on the poles where neutral is seperate from ground?

Let me say something that will seem funny at first. If you take a transformer, any transformer, like the one at the top of the utility pole, or like the one earlier in this thread that might go in your basement, it doesn't matter. Anyway, if you take a transformer with two wires coming out of it carrying voltage, then at this point no wire is "neutral" and no wire is "hot". There is no neutral. Neutral is created by connecting one wire to a rod in the ground. Until we do that there are just two wires with voltage between them.

Think about an analogy with a 3 ft rule. First hold it up in your hand. The ruler is 3 ft long (240 V), but it is floating and not grounded. This is like the transformer with two wires 240 V (3 ft) apart.

Next stand it upright on the ground. Now the lower end (0 ft) is grounded, and the other end (3 ft) is 3 ft up in the air, but the ruler is still 3 ft long. You could call the lower end of the ruler "neutral".

Next, dig a three foot deep hole and drop the ruler down it. Now the top end (3 ft) is level with the ground and the bottom end (0 ft) is 3 ft below ground. The ruler is still 3 ft long, but now the top end is grounded. You could call the top end of the ruler "neutral" because there is no distance to fall between that end and ground level.

Lastly, dig a  1½ ft hole and stand the ruler in that. Now the ruler is half above ground and half below ground. It is still 3 ft (240 V) long, but now the middle is grounded. This is what split phase is like. The maximum distance to fall to ground level is 1½ ft (120 V), which makes it a bit safer.

[IanB]

I could technically power a circuit where the supply is 24V and the return is 12V.

No, in a two wire system it is not possible "to have one wire at 24 V and the other at 12 V". Voltage is defined as the difference in potential between two wires. No single wire can ever have a voltage on it in isolation. Every time you talk about a voltage you have to talk about the voltage between this wire and that wire. So all you can say about two wires is that "they have a voltage of 12 V". All you can say about a single wire is "we don't know anything about voltages because there is only one wire". (Sometimes the other "wire" can be ground, or a water pipe, or something, but this is still a "wire" from an electrical and safety perspective.)

With the 120-0-120, I understand how it works now.   I also understand why if I were to not use a double pole breaker but tried wiring up a NEMA L6-30R using a 30-amp single pole breaker in slot 1 and slot 2 (opposites sides of the panel), it wouldn't work.   I'd have 120VAC, not 240VAC.

No, you don't seem to understand. You would have 240 V AC, which is exactly what the computer power supplies want. The reason you can't hook up your existing PDU to the L6-30R receptacle is one of safety. It doesn't comply with North American electrical standards. It was designed for another system, outside North America.

[Spork Schivago]

With the European 240VAC, don't they generally have 240VAC going down L1 and Neutral to Neutral, Ground to Ground (where Neutral would be connected to Ground, like in my breaker panel)?   If so, wouldn't they receive a short if they tried hooking my BGA rework station (which is wired with L1 = 120VAC, L2 = 120VAC, N = Neutral, E = Earth) directly into their outlets, just by changing the NEMA L6-30P I wired to the end of it?

You have listed four wires (L1, L2, N, E), but in the L6-30P there are only supposed to be three wires (L1, L2, E). There is no neutral.

Your BGA rework station is only supposed to have three wires too. In the European outlet there are two wires carrying 240 V between them, and a third wire for safety ground. In the USA the L6-30 receptacle has two wires carrying 240 V between them and a third wire for safety ground. So the situation is really the same in Europe as it is here from an electrical perspective. It is only the safety arrangements that differ.

We call a wire "hot" or "live" because it is effectively hot and will hurt you if you touch it. We call a wire neutral because--theoretically--it won't hurt you if you touch it (but don't rely on this). There is no difference between live and neutral as far as carrying electric current is concerned, there is only a difference with regard to safety and protection arrangements.

I'm sorry, I haven't gotten a lot of sleep lately, but yes, you are correct.   The NEMA L6-30P / L6-30R only has 3 wires, not four.    So in Europe and other parts of the world that use 240VAC, it's just like ours, where 120V goes down one wire, 120V goes down another?   This is what my European friend was talking about I think when he said it was a language barrier and that Neutral was meant to be hot.   If that's the case though, and they have two wires carrying the 240V load, then my PDU wouldn't work over there either, would it?   Because we still have single pole breakers.   They'd need 1-phase 240VAC, not two-phase.

This guy I know had me come to his house to fix his electricity.   He's really intelligent, but should not be messing with this stuff, and I stressed that many times, but he said if his house burned up with him in it, he'd be happy.   Anyway, he had a furnace in his basement and lives downstairs.   He wired up some sort of forced air, which was just pure genuis, but he wired the receptacle incorrectly and it didn't trip a breaker, but sparked.   Then none of the loads on the circuit worked.   So I went through and probed them with my multimeter and I have a small device I plug in to show me if they're wired correctly, and a no-contact voltage detector.

I'm working my way backwards, right?   I get to this receptacle, plug my device in, nothing, but the no-contact voltage detector says there's juice.   I put my DMM on there, 14VAC.   I'm like what the heck?   I know it was dumb, but I had to check.   I touch the receptacle, and sure enough, a bit of a tingle.    I go down stairs, trace the wire, and come to a junction box.   This is where it gets real bad.    He tied into 12-gauge wire using 14-gauge wire and ran it to the new receptacle he installed for his forced air hookup.

Every outlet in the house had no ground wire hooked up, and this is why it never tripped the breaker.   In the actual junction box, the wirenut had actually partiatially exploded.   Some of it was melted.   I told him this is why you need to not be doing this.   I can show you how to do it safely, but you cannot have this type of setup, you're going to get hurt or killed.   That's when he said he didn't care, so I didn't know what to do.   I fixed it, but said he shouldn't be using the 14-gauge.   It's a danger.   He needs to switch it out with 12-gauge.   I tried telling him, how would you feel if you was at work and your house burned down and your dogs couldn't get out?   I dunno if he ever switched it out or not.   He got real paranoid after that and started talking about cameras in the tree's and the FBI watching him or something so I left.

[Spork Schivago]

I could technically power a circuit where the supply is 24V and the return is 12V.

No, in a two wire system it is not possible "to have one wire at 24 V and the other at 12 V". Voltage is defined as the difference in potential between two wires. No single wire can ever have a voltage on it in isolation. Every time you talk about a voltage you have to talk about the voltage between this wire and that wire. So all you can say about two wires is that "they have a voltage of 12 V". All you can say about a single wire is "we don't know anything about voltages because there is only one wire". (Sometimes the other "wire" can be ground, or a water pipe, or something, but this is still a "wire" from an electrical and safety perspective.)

With the 120-0-120, I understand how it works now.   I also understand why if I were to not use a double pole breaker but tried wiring up a NEMA L6-30R using a 30-amp single pole breaker in slot 1 and slot 2 (opposites sides of the panel), it wouldn't work.   I'd have 120VAC, not 240VAC.

No, you don't seem to understand. You would have 240 V AC, which is exactly what the computer power supplies want. The reason you can't hook up your existing PDU to the L6-30R receptacle is one of safety. It doesn't comply with North American electrical standards. It was designed for another system, outside North America.

No, I do understand.    slot 1 and slot 2 are on the same phase, from the panels perspective.   Take two computer PSUs.   Strip the 12V wire from each of them.   Tie them together.   Plug both into the same outlet.   Measure the voltage in reference to ground.   What do you get?   24VDC?   No.   12VDC.    Now, do the same, but plug one of the PSUs into a circuit powered by the other mains coming into the house.   What do you get?   Should be 24VDC, not 12VDC.

I'm tired, I did a horrible job, I was trying to give a simple analogy of something we call differential signaling, but after I get some sleep, I'll come back and update it proper like.   I have been awake for over 36 hours now.   I gotta go to bed, but I love talking to you guys and learning this stuff.   So hard to walk away.

[IanB]

With that in mind, if you were me, would you take the chance and send the PDU back and order the other two, plus the additional equipment to get it running?  Or would you just purchase the transformer and new breaker panel?

I would send the PDU back and order the other two PDUs. The reason being that that other PDUs are designed and specified for installation in North America and they comply with the electrical and safety requirements of the North American electrical code.

Your existing PDU is not code compliant and is not suitable for connection to a North American electrical supply. It is intended for another market elsewhere in the world. This is why it has a strange plug on it and why electricans don't want to touch it.

You could, theoretically, install the transformer and the sub-panel, but it's going to be really complicated getting it to pass inspection because it will be a strange and abnormal setup.

If you don't want to take the responsibility of ordering the other PDUs just on the advice of this forum, you should find someone in your line of business to consult who can offer appropriate expert advice. I do not think you have been well advised by the HPE sales consultants in your journey so far.

[IanB]

slot 1 and slot 2 are on the same phase, from the panels perspective

No, slot 1 and slot 2 are on the opposite phase, from the panel's perspective. That is why slot 1 and slot 2 have 240 V between them.

[Richard Crowley]

Because we don't have an L1 and L2,

But we DO have L1 and L2. Those are the names of the two "hot" wires coming into your house.  Between L1 and L2 are 240VAC.

In North America, the center-tap between L1 and L2 is grounded and all the 120V loads are connected between the center tap (called "Neutral") and EITHER L1 or L2, so you get half the incoming 240V  And 240V loads are connected BETWEEN L1 and L2.

In most of the rest of the world, they use L1 and L2 (240V) directly.  In many cases "L1" is grounded and called "Neutral". That is the industrial standard and that is what your PDU is designed for.

In some parts of the 240V world, BOTH sides (L1 and L2) are "above ground" and not even ground-referenced at all. They must treat ALL the wires as "hot" except the green-wire safety ground (which they call "PE" Proective Earth)  Because of this, much (most?) 240 volt equipment is designed with the assumption that BOTH sides are "hot".  That is why I find it so curious that you claim that your loads (servers) won't operate if both L1 and L2 are "hot".

because the 240VAC is on the same phase, where do the electrons go if they're not hooked to a neutral or ground to complete the circuit?    Somehow they have to make it back to the breaker, correct? 

The electrons go BETWEEN L1 and L2.  When you say "because the 240VAC is on the same phase" it makes no sense.  That is like saying that a yard-stick is 36 inches long no matter if you hold it at one end or the other end.  Or if you hold it in the middle ("split-phase")

I use the word ground, but all I mean is a completed circuit.   I know and understand that a completed circuit doesn't need a ground or a voltage potential of 0V.   I could technically power a circuit where the supply is 24V and the return is 12V.   So long as the return is at a lower voltage potential than the supply, we can have the electrons moving.

Yes, for 1/120th of a second. And then 1/120th of a second later, the 240V has changed to the opposite polarity (which is why it is called ALTERNATING current.

Using the water analogy that everyone seems to like to use, we have our "pump" (the transformer I'd buy for the PDU, for example).   The "water" (electrons) flow out of L1 into the PDU.   But then what?

The current flows around the loop from L1 through L2 back to the transformer on the pole.  The center-tap is there to split the 240V in half so that our historic North American standard of 120V loads can get 120V and not the full 240V coming into your house.

They need to make it back to the "pump" (transformer) somehow.    I know you say ground / neutral is irrelevant, but in this case, I cannot imagine how those pesky little buggers would make it back to complete the circuit without using one of those other wires that are at 0V potential.

   
Neither L1 nor L2 are  "at 0V potential".  Even "Neutral" wouldn't be "at 0V potential" unless it was (artificially) grounded.  The current flow of a 240V load never sees neutral/ground.

The components inside the PDU would be the loads

No. The things (computers) plugged into the PDU are the loads.  The PDU is just a fancy, expensive power-strip.

and by the time the current / electricity had passed through the entire circuit and was ready to leave the PDU, it surely wouldn't just be traveling up the L1 wire again, would it? 

A 240V load current passes between L1 and L2.  It does not know or care whether either side (or the center-tap) is grounded or not.

We'd have to use one of the additional neutral / ground wires in that instance. 

NO!  240V loads use the current between L1 and L2. Neutral/ground plays no part here.  Neutral is provided only for 120V loads.

Just like if we're dealing with 120VAC receptacles.   We cannot just hook up the hot wire.   That wouldn't do diddly squat.   We'd still have to hook up the neutral so the electrons could make it back to the panel.

Yes. From the hot wire (which is either L1 or L2) to Neutral is 120V.  But between L1 and L2 is 240V.  That is what 240V loads use.

With the 120-0-120, I understand how it works now.   I also understand why if I were to not use a double pole breaker but tried wiring up a NEMA L6-30R using a 30-amp single pole breaker in slot 1 and slot 2 (opposites sides of the panel), it wouldn't work.   I'd have 120VAC, not 240VAC.

Huh?  There is no such thing as a "single pole breaker in slot 1 and slot 2". Each "slot" is a pole. Between each "slot" and Neutral is 120V. But between two adjacent "slots" is 240V because all the odd number slots are connected to L1 and all the even number slots are connected to L2.  Do not be confused thinking that the left side of the breaker panel is L1 and the right side is L2. The "slots" alternate between L1 and L2 so that you can use a double breaker to provide a 240V branch circuit from two adjacent slots.

Zoom in on this photo to see the details.  L1 and L2 come in at the top from the transformer out on the pole (or buried under the sidewalk). The Neutral comes in to that big terminal at the upper right.  And it is connected to the light-colored screw terminal strip on the right side.  If you look very carefully, you will see that one of the screws in the neutral strip is colored green.  That is where the Neutral is connected to Ground in the North American standard.

Then EVERY OTHER slot is connected to either L1 or L2.  So if you put in a single-pole breaker, you connect to EITHER L1 or L2 and the return path comes back through the Neutral.  But if you install a double-pole breaker one pole connects to L1 and the other pole connects to L2. Because between L1 and L2 is 240V and the load current comes from L1, passes through the load, and returns to L2.  At least for 1/120th of a second.  And in the next 1/120th of a second the current flows from L2, through the load and back to L1.

Notice that during the discussion of a double-pole, 240V circuit there was no mention of Neutral.  And I didn't have one up my sleeve, either.

[IanB]

I'm sorry, I haven't gotten a lot of sleep lately, but yes, you are correct.   The NEMA L6-30P / L6-30R only has 3 wires, not four.    So in Europe and other parts of the world that use 240VAC, it's just like ours, where 120V goes down one wire, 120V goes down another?

No, there's no 120 V anywhere. Recall that voltage is measured as the difference between two wires. There are only two power conductors in the L6-30 and they carry 240 V. There is simply 240 V between the two power conductors. That's it. End of story. There is no 120 V in a correctly wired L6-30 plug or receptacle. Only 240 V. (Ignore the ground for this discussion, it is there for safety, not for power delivery.)

This is what my European friend was talking about I think when he said it was a language barrier and that Neutral was meant to be hot.   If that's the case though, and they have two wires carrying the 240V load, then my PDU wouldn't work over there either, would it?   Because we still have single pole breakers.   They'd need 1-phase 240VAC, not two-phase.

Breakers are about safety and system protection. If both power conductors are "hot" then each power conductor needs a breaker (a "2-pole breaker"). In North America the 208 V AC or 240 V AC supply typically has two hot conductors, so it needs the 2-pole breaker. This is what the NA/Japan models of PDU provide.

In other parts of the world only one power conductor may be "hot", in which case only the hot conductor needs a breaker (a "single pole breaker"). This is what the INTL or WW models of PDU provide. They are suitable for parts of the world like Europe, but they are not code compliant for use in North America.

Again, this is all about safety and system protection and code compliance. It is not about voltages or power requirements.

[james_s]

That's what I've been missing.   I wasn't talking about the transformer here, I was talking about 120-0-120 split-phase that comes into the house, and trying to see how it's equivalent to 240VAC over in Europe.   Because over there, they'll have L1 and then Neutral hooked to the heating elements, which would still give the 240VAC.   I think I understand now fully how the AC works.

Now, why would connecting earth ground to a 240VAC source that comes from 120-0-120VAC USA split-phase or whatever you want to call it cause a short there?   It's because L1 and L2 are reciprocals of each other, right?  When one is 120VAC, the other is -120VAC.   When one is 75VAC, the other is -75VAC.   When one is zero, the other is zero.   If we added a ground, when either where anything other than 0VAC, we'd have our direct connection to ground, which would be horrible.   Am I finally understanding this?

Look at the schematic of the center tapped transformer winding, you have 3 wires coming out of that transformer, L1 and L2 are the ends and CT from the middle. Now in the North American setup CT is connected to ground, so now what happens when you also connect either L1 or L2 to ground? Draw it on paper if you have to but you should see a direct short across half of the secondary.

[Spork Schivago]

With that in mind, if you were me, would you take the chance and send the PDU back and order the other two, plus the additional equipment to get it running?  Or would you just purchase the transformer and new breaker panel?

I would send the PDU back and order the other two PDUs. The reason being that that other PDUs are designed and specified for installation in North America and they comply with the electrical and safety requirements of the North American electrical code.

Your existing PDU is not code compliant and is not suitable for connection to a North American electrical supply. It is intended for another market elsewhere in the world. This is why it has a strange plug on it and why electricans don't want to touch it.

You could, theoretically, install the transformer and the sub-panel, but it's going to be really complicated getting it to pass inspection because it will be a strange and abnormal setup.

If you don't want to take the responsibility of ordering the other PDUs just on the advice of this forum, you should find someone in your line of business to consult who can offer appropriate expert advice. I do not think you have been well advised by the HPE sales consultants in your journey so far.

Yeah, I agree with you on the HPE sales consultants.   We had this issue with Microsoft as well.   They've gotten so big, they can't keep track of all the licenses and agreements.   For example, one sales person said we could just use Windows Home edition to run our business, another said Pro or higher, another said we needed VL editions, finally, a sales rep said we needed the CSP (Cloud Service Provider) agreement, which we signed up for.   Then, on Spice Works, a Senior Project Manager who works directly for Microsoft and has an account on Spiceworks, helping people with licenses and everything, says no, CSP is not meant for on-premise servers.   If we hosted our servers off-premise or in the cloud, we'd be okay.   There was some hassle between getting my one VAR who sold us the licenses to talk to this guy, but I don't think they realized how much pull he had.   And he made contact with them, letting them know he wasn't just some idiot on the net surfing the forums.    I guess still, him and the guy who sold us the CSP are arguing over it.

Hopefully, we get to keep the CSP stuff, because I like it and it's a hell of a lot cheaper than purchasing Windows Server edition, now that  it's Core-Based, especially with the number of VMs we need.

I think maybe the same happened with HPE, or perhaps, the technician saw a chance to up-sell me on the PSU and said hey, you need this 1400 watt PSU.    The only reason this PDU was picked was because it was supposedly compatible with the PSUs.    I hate having to have a whole bunch of PDUs in the rack, but if that's the way I gotta do it, that's the way I gotta do it.   I just really hope you guys are right about this being able to run off 120-0-120VAC and they (HPE) are wrong.   The only thing I worry about on the PSU is that intelligent connector for the intelligent PDUs.   The cables aren't normal PSU cables.   The input on the PSU, it's got inside of it, three pins to power it, and then on the bottom, underneath those three pins, it has four pads.   It's those four pads I worry about.   The 500 watt ones that were in it, before the upgrades, they ain't got those pads there but those were made for not the intelligent PDUs.

I'll have to wait until Monday, but I'll see if I can send the PDU back.   I've had it a while now, because I was working on getting the transformer money around and all that jazz.

[Spork Schivago]

slot 1 and slot 2 are on the same phase, from the panels perspective

No, slot 1 and slot 2 are on the opposite phase, from the panel's perspective. That is why slot 1 and slot 2 have 240 V between them.

On my panel, double pole breakers go every other, slot 1 and slot 3, or slot 2 and slot 4.   So I'd think 1 and 2 would both be on L1, where 3 and 4 would be on L2.

[Spork Schivago]

Because we don't have an L1 and L2,

But we DO have L1 and L2. Those are the names of the two "hot" wires coming into your house.  Between L1 and L2 are 240VAC.

In North America, the center-tap between L1 and L2 is grounded and all the 120V loads are connected between the center tap (called "Neutral") and EITHER L1 or L2, so you get half the incoming 240V  And 240V loads are connected BETWEEN L1 and L2.

In most of the rest of the world, they use L1 and L2 (240V) directly.  In many cases "L1" is grounded and called "Neutral". That is the industrial standard and that is what your PDU is designed for.

In some parts of the 240V world, BOTH sides (L1 and L2) are "above ground" and not even ground-referenced at all. They must treat ALL the wires as "hot" except the green-wire safety ground (which they call "PE" Proective Earth)  Because of this, much (most?) 240 volt equipment is designed with the assumption that BOTH sides are "hot".  That is why I find it so curious that you claim that your loads (servers) won't operate if both L1 and L2 are "hot".

HPE claims the loads won't work if I try wiring this PSU up to 120-0-120.   But I don't know if this matters, there's more inputs than just the three wires on the 1400 watt PSU.   There's actually a total of 7.   4 of which are made to communicate with the intelligent PDUs (which I don't have, and didn't want, because I don't like them but might  have been able to purchase one of those).   This was the only reason I was thinking HPE might have been correct, those four pads inside the connector there....but I'm going to try and send the PDU back now and purchase the ones made for 120-0-120 and see how it actually works, see if they're wrong and you guys are right.   You guys seem to really know your shit, and everything you guys have said has made since.

because the 240VAC is on the same phase, where do the electrons go if they're not hooked to a neutral or ground to complete the circuit?    Somehow they have to make it back to the breaker, correct? 

The electrons go BETWEEN L1 and L2.  When you say "because the 240VAC is on the same phase" it makes no sense.  That is like saying that a yard-stick is 36 inches long no matter if you hold it at one end or the other end.  Or if you hold it in the middle ("split-phase")

I use the word ground, but all I mean is a completed circuit.   I know and understand that a completed circuit doesn't need a ground or a voltage potential of 0V.   I could technically power a circuit where the supply is 24V and the return is 12V.   So long as the return is at a lower voltage potential than the supply, we can have the electrons moving.

Yes, for 1/120th of a second. And then 1/120th of a second later, the 240V has changed to the opposite polarity (which is why it is called ALTERNATING current.

Using the water analogy that everyone seems to like to use, we have our "pump" (the transformer I'd buy for the PDU, for example).   The "water" (electrons) flow out of L1 into the PDU.   But then what?

The current flows around the loop from L1 through L2 back to the transformer on the pole.  The center-tap is there to split the 240V in half so that our historic North American standard of 120V loads can get 120V and not the full 240V coming into your house.

But we're not talking about the center tapped 120-0-120VAC source.   I'm talking about the transformer, if I bought that.   But after you saying we still have an L1 and L2, I believe I understand.   It doesn't matter, to the PDU, if L1 and L2 are both hot (120VAC different phases) or one hot (240VAC) and the other neutral.   It acts the same.

They need to make it back to the "pump" (transformer) somehow.    I know you say ground / neutral is irrelevant, but in this case, I cannot imagine how those pesky little buggers would make it back to complete the circuit without using one of those other wires that are at 0V potential.

   
Neither L1 nor L2 are  "at 0V potential".  Even "Neutral" wouldn't be "at 0V potential" unless it was (artificially) grounded.  The current flow of a 240V load never sees neutral/ground.

The components inside the PDU would be the loads

No. The things (computers) plugged into the PDU are the loads.  The PDU is just a fancy, expensive power-strip.

Yes, but each component inside the PDU is also a load.   And because there's circuitry that's running with nothing plugged into the PDU at all, the PDU is still considered a load itself.   If it wasn't, it'd be 100% efficient, instead of 80% efficient while running at x voltage, 85% efficient while running at y voltage, and 90% efficient while running at z voltage.

and by the time the current / electricity had passed through the entire circuit and was ready to leave the PDU, it surely wouldn't just be traveling up the L1 wire again, would it? 

A 240V load current passes between L1 and L2.  It does not know or care whether either side (or the center-tap) is grounded or not.

We'd have to use one of the additional neutral / ground wires in that instance. 

NO!  240V loads use the current between L1 and L2. Neutral/ground plays no part here.  Neutral is provided only for 120V loads.

You're saying if I kept the PDU, bought that transformer, neutral / ground plays no part?   L1 and L2 are still hot?    I thought the whole purpose of the transformer was to get one 240VAC L1....because we only have one-pole breakers inside of the PDU....If L1 and L2 both have current going through them, how would this transformer protect me if one of those internal breakers where to trip?   We'd still have current going through half the output.

Just like if we're dealing with 120VAC receptacles.   We cannot just hook up the hot wire.   That wouldn't do diddly squat.   We'd still have to hook up the neutral so the electrons could make it back to the panel.

Yes. From the hot wire (which is either L1 or L2) to Neutral is 120V.  But between L1 and L2 is 240V.  That is what 240V loads use.

With the 120-0-120, I understand how it works now.   I also understand why if I were to not use a double pole breaker but tried wiring up a NEMA L6-30R using a 30-amp single pole breaker in slot 1 and slot 2 (opposites sides of the panel), it wouldn't work.   I'd have 120VAC, not 240VAC.

Huh?  There is no such thing as a "single pole breaker in slot 1 and slot 2". Each "slot" is a pole. Between each "slot" and Neutral is 120V. But between two adjacent "slots" is 240V because all the odd number slots are connected to L1 and all the even number slots are connected to L2.  Do not be confused thinking that the left side of the breaker panel is L1 and the right side is L2. The "slots" alternate between L1 and L2 so that you can use a double breaker to provide a 240V branch circuit from two adjacent slots.

Zoom in on this photo to see the details.  L1 and L2 come in at the top from the transformer out on the pole (or buried under the sidewalk). The Neutral comes in to that big terminal at the upper right.  And it is connected to the light-colored screw terminal strip on the right side.  If you look very carefully, you will see that one of the screws in the neutral strip is colored green.  That is where the Neutral is connected to Ground in the North American standard.

Then EVERY OTHER slot is connected to either L1 or L2.  So if you put in a single-pole breaker, you connect to EITHER L1 or L2 and the return path comes back through the Neutral.  But if you install a double-pole breaker one pole connects to L1 and the other pole connects to L2. Because between L1 and L2 is 240V and the load current comes from L1, passes through the load, and returns to L2.  At least for 1/120th of a second.  And in the next 1/120th of a second the current flows from L2, through the load and back to L1.

Notice that during the discussion of a double-pole, 240V circuit there was no mention of Neutral.  And I didn't have one up my sleeve, either.

Yes, that's exactly what I was saying.   Every other slot is connected to L1 or L2.   If you where to hook single pole breakers to slot 1 and 2 (where slot 1 is hooked to L1 and slot 2 is hooked to L1), you won't get the 240VAC.   You'd get 120VAC.   You'd just be able to draw more current.   This is why those people that suggest making a DIY plug that just plugs into the two inputs on the same receptacle and are supposed to provide 240VAC will never work.   You need the supply from L1 and L2, not L1 and L1, or L2 and L2.

What I was saying was you take two single pole breakers, if you connect one to slot number 1 in the panel, and connect one to slot number 3, you've essentially created a double-pole breaker.   It wouldn't be safe, because if one breaker tripped, there's no guarantee the other would.    slot number 1 and 3 are L1, for example, 2 and 4 are L2 for example.   If you were to connect two single pole breakers, one to slot 1 and one to slot 2, and wire them expecting 240VAC between them, you wouldn't get it because both breakers would be on L1 or both breakers would be on L2.   This was my way of showing that I understood it, describing back what I learned, in my own words.

[IanB]

On my panel, double pole breakers go every other, slot 1 and slot 3, or slot 2 and slot 4.   So I'd think 1 and 2 would both be on L1, where 3 and 4 would be on L2.

Fair enough, I probably just used the wrong words. I'm just trying to say that for a 240 V circuit the double pole breaker connects between L1 and L2, and this gives 240 V single phase. In the house wiring L1 would be the black wire and L2 would be the red wire (or vice versa--it doesn't really matter). To wire a 240 V circuit from this breaker you would use a three conductor cable with red, black and ground wires.

[IanB]

This was the only reason I was thinking HPE might have been correct, those four pads inside the connector there....but I'm going to try and send the PDU back now and purchase the ones made for 120-0-120 and see how it actually works, see if they're wrong and you guys are right.

Please don't say "120-0-120" or "split phase" or anything like that to the sales people. It will cause confusion and get you into trouble.

What you need to say is "200 to 240 V AC single phase for use in the USA". A compatible PDU should be provided with 2-pole breakers for complete isolation of the supply, and the PSUs actually don't care. As long as the PSU is designed for "high-line" 200 to 240 V AC input it will be fine.

[IanB]

A quick summary.

Here are the PDU specs:



The P9S13A says "North America/Japan, single phase 200 to 240 V input, 24 amps input, fitted with two 2-pole 20 A breakers." Therefore it can distribute 24 A to servers or other equipment.

Here are the PSU specs:



It can run off 200 to 240 V AC, single phase, at 50 to 60 Hz. Running at full load at 240 V it will draw 6.5 amps. Therefore you could probably run four of these PSUs from one P9S13A PDU, assuming that the PSUs are not going to be running flat out. (Notice it also gives the heat rating in BTU/hr to estimate the required cooling in the server room. The air conditioning unit has to remove 5300 BTU/hr for each one of these power supplies.)

[Spork Schivago]

I'm sorry, I haven't gotten a lot of sleep lately, but yes, you are correct.   The NEMA L6-30P / L6-30R only has 3 wires, not four.    So in Europe and other parts of the world that use 240VAC, it's just like ours, where 120V goes down one wire, 120V goes down another?

No, there's no 120 V anywhere. Recall that voltage is measured as the difference between two wires. There are only two power conductors in the L6-30 and they carry 240 V. There is simply 240 V between the two power conductors. That's it. End of story. There is no 120 V in a correctly wired L6-30 plug or receptacle. Only 240 V. (Ignore the ground for this discussion, it is there for safety, not for power delivery.)

I think you're misunderstanding what I'm saying.   I correctly wired my NEMA L6-30P.  When L1 is referenced to L2 there's ~240VAC.   When L1 is referenced to Ground there's ~120VAC.   When L2 is referenced to Ground there's ~120VAC.   I understand the Ground is solely for safety purposes, trust me.   I'm asking, in Europe and other parts of the world, where most appliances are designed to run off 240VAC, not 120VAC, on their receptacles, when L1 is referenced to Ground, is it ~240VAC or ~120VAC?   When L2 is referenced to ground, is ~120VAC or 0VAC?   That's what I'm asking.   I know what it is in the USA with the NEMA plugs.   I know the 240VAC is acquired by referencing L1 and L2...

This is what my European friend was talking about I think when he said it was a language barrier and that Neutral was meant to be hot.   If that's the case though, and they have two wires carrying the 240V load, then my PDU wouldn't work over there either, would it?   Because we still have single pole breakers.   They'd need 1-phase 240VAC, not two-phase.

Breakers are about safety and system protection. If both power conductors are "hot" then each power conductor needs a breaker (a "2-pole breaker"). In North America the 208 V AC or 240 V AC supply typically has two hot conductors, so it needs the 2-pole breaker. This is what the NA/Japan models of PDU provide.

In other parts of the world only one power conductor may be "hot", in which case only the hot conductor needs a breaker (a "single pole breaker"). This is what the INTL or WW models of PDU provide. They are suitable for parts of the world like Europe, but they are not code compliant for use in North America.

Again, this is all about safety and system protection and code compliance. It is not about voltages or power requirements.

That's what I was asking.   In Europe, are there two power conductors that are hot or just one?   In America, with 240VAC using our 120-0-120 split phase, both conductors, L1 and L2 are hot, each providing 120VAC out of phase from each other by 180°.   Why 180°?   Because 180° + 180° = 360° so when L1 is +120VAC, L2 will be -120VAC, give or take.   L1 and L2 will should always be the same voltage, but opposite signs of each other.   So when L1 is at +20VAC, L2 should be at -20VAC.   That's why they're 180° out of phase from each other.   If they where something like 120° out of phase with each other, L1 might be +120VAC, and L2 wouldn't be -120VAC.

[Monkeh]

In the majority of european countries (to my knowledge, I am aware some countries have three phase domestically), domestic properties are supplied with one phase and a neutral from a 3-phase 400V supply. So L is 230V to N, there is no L2, and N is nominally 0V to ground. This is what the PDUs you have are designed for.

[Spork Schivago]

That's what I've been missing.   I wasn't talking about the transformer here, I was talking about 120-0-120 split-phase that comes into the house, and trying to see how it's equivalent to 240VAC over in Europe.   Because over there, they'll have L1 and then Neutral hooked to the heating elements, which would still give the 240VAC.   I think I understand now fully how the AC works.

Now, why would connecting earth ground to a 240VAC source that comes from 120-0-120VAC USA split-phase or whatever you want to call it cause a short there?   It's because L1 and L2 are reciprocals of each other, right?  When one is 120VAC, the other is -120VAC.   When one is 75VAC, the other is -75VAC.   When one is zero, the other is zero.   If we added a ground, when either where anything other than 0VAC, we'd have our direct connection to ground, which would be horrible.   Am I finally understanding this?

Look at the schematic of the center tapped transformer winding, you have 3 wires coming out of that transformer, L1 and L2 are the ends and CT from the middle. Now in the North American setup CT is connected to ground, so now what happens when you also connect either L1 or L2 to ground? Draw it on paper if you have to but you should see a direct short across half of the secondary.

Yes, with North American setup.   But with the transformer I was going to purchase, I was under the impression if you connect L2 to ground there is no short.   I was under the impression that was the whole reason I needed to purchase that specific transformer that Mr. Crowley originally suggested, because of the single-pole breakers inside of the PDU that I was sold.   So L1 is the only hot wire, with ~240VAC in reference to ground or in reference to L2 (but only with that transformer Mr. Crowley suggested I purchase if I were to continue to keep the current PDU and wanted to maintain safety.)   That way, if one of the breakers tripped, it'd cut the path of L1, but L2 and N would still be active, but wouldn't be a danger.    I think you guys missed the part where I said the transformer that I was going to purchase and think that I'm talking about the transformer on the pole in North America.

With the transformer Mr. Crowley suggested I purchase if I were going to keep the PDU, there shouldn't be an L2 on the secondary side, if I understand everything correctly.   There's only an L1, an N, and an E.   With American transformers, yes, if we connect either L1 or L2 to ground, we get a direct short and the breaker (hopefully!) trips to protect us.   Or, with that transformer Mr. Crowley suggested I purchase if I were going to keep the PDU, on the PRIMARY side, if I connected L1 OR L2 to ground, we'd have a dead short and that'd be horrible and hopefully the double-pole breaker on the mains panel would protect us and trip.   But if we were to be doing that, we shouldn't be playing with electricity until we learned a lot more about it.

[Spork Schivago]

This was the only reason I was thinking HPE might have been correct, those four pads inside the connector there....but I'm going to try and send the PDU back now and purchase the ones made for 120-0-120 and see how it actually works, see if they're wrong and you guys are right.

Please don't say "120-0-120" or "split phase" or anything like that to the sales people. It will cause confusion and get you into trouble.

What you need to say is "200 to 240 V AC single phase for use in the USA". A compatible PDU should be provided with 2-pole breakers for complete isolation of the supply, and the PSUs actually don't care. As long as the PSU is designed for "high-line" 200 to 240 V AC input it will be fine.

Good to go!   Now, when you say don't say 120-0-120 or split phase or anything like that to the sales people, is that because it's incorrect or it will just confuse them?   Am I using the wrong terminology here?   I understand the difference between technicians and sales people and I learned a long time ago when I was working on PCs for customers to not get technical.   Keep it simple, no need to confuse them, just say it's fixed, you owe me blah.   Found a bad component or two (something along those lines), rather than saying the capacitors in the VRM circuit blew because of them being directly under the heatsink and not having adequate cooling or the proper heatsink, so I replaced them with high temp Panasonic's and purchased a taller, yet not as wide heatsink with a fan that could push more air per CFM through the heatsink then the previous one.

[Monkeh]

This was the only reason I was thinking HPE might have been correct, those four pads inside the connector there....but I'm going to try and send the PDU back now and purchase the ones made for 120-0-120 and see how it actually works, see if they're wrong and you guys are right.

Please don't say "120-0-120" or "split phase" or anything like that to the sales people. It will cause confusion and get you into trouble.

What you need to say is "200 to 240 V AC single phase for use in the USA". A compatible PDU should be provided with 2-pole breakers for complete isolation of the supply, and the PSUs actually don't care. As long as the PSU is designed for "high-line" 200 to 240 V AC input it will be fine.

Good to go!   Now, when you say don't say 120-0-120 or split phase or anything like that to the sales people, is that because it's incorrect or it will just confuse them?   Am I using the wrong terminology here?

The terminology is fine, but the people on the other end of the phone have absolutely no idea about the concepts of electrical installations. Even the techs you may speak to don't - they leave it all to the electricians and just know how to add simple numbers together for load calculations.

As I said earlier, all you'll get from the people you're able to contact is them reading '240VAC single-phase' off the datasheet and parroting it back. The only people directly involved in any of this hardware who know better are the ones designing the supplies - and they work for Delta and Flextronics, and speak Chinese.

[IanB]

That's what I was asking.   In Europe, are there two power conductors that are hot or just one?   In America, with 240VAC using our 120-0-120 split phase, both conductors, L1 and L2 are hot, each providing 120VAC out of phase from each other by 180°.   Why 180°?   Because 180° + 180° = 360° so when L1 is +120VAC, L2 will be -120VAC, give or take.   L1 and L2 will should always be the same voltage, but opposite signs of each other.   So when L1 is at +20VAC, L2 should be at -20VAC.   That's why they're 180° out of phase from each other.   If they where something like 120° out of phase with each other, L1 might be +120VAC, and L2 wouldn't be -120VAC.

Yes, in parts of Europe like the UK you have one live conductor at ~240 V referenced to ground and one neutral conductor at ~0 V.

Therefore in Europe, isolating the single live conductor and leaving the neutral conductor connected is safe (for example with a single pole breaker). Hence the "INTL" or "WW" PDUs have a single pole breaker.

However, using a single pole breaker in the USA where both conductors are hot is not safe. Both conductors have to be isolated (for example with a two pole breaker). Hence the "NA/Japan" PDUs are fitted with two pole breakers.

[Spork Schivago]

A quick summary.

Here are the PDU specs:



The P9S13A says "North America/Japan, single phase 200 to 240 V input, 24 amps input, fitted with two 2-pole 20 A breakers." Therefore it can distribute 24 A to servers or other equipment.

Here are the PSU specs:



It can run off 200 to 240 V AC, single phase, at 50 to 60 Hz. Running at full load at 240 V it will draw 6.5 amps. Therefore you could probably run four of these PSUs from one P9S13A PDU, assuming that the PSUs are not going to be running flat out. (Notice it also gives the heat rating in BTU/hr to estimate the required cooling in the server room. The air conditioning unit has to remove 5300 BTU/hr for each one of these power supplies.)

I wasn't even going to tell them I needed a PDU that runs off 200 - 240VAC made for North America with two-pole breakers.   My Account Executive is NOT a technician, he is the person that talks to the technicians.   So I was going to say on the phone or email on Monday, hey, is it too late to send that P9S16A PDU back and purchase a couple P9S13A PDU's?

I'll have to do the math real quick to determine how many PDUs I actually need.   I have more than just the servers in the rack, but it would be nice if I could divey up the servers between two different PDUs for redundancy purposes.

I had already looked at the heat they produce and calculated what size AC I was going to need.   I used those as a rough estimate for the other equipment, just to take an educated guess and overestimated a little.   It's a pretty big AC.

Anyway, when I ordered the plugs for all the equipment the PDU was going to power, I ordered a few extras, just for expansion later on and to have.   I came up with an idea.   I have that NEMA L6-30R wired up, and I wired the NEMA L6-30P myself for the BGA rework station.    I'm wondering if one of these servers could run with just one PSU, and I think it can right now, at least temporarily.    I'm thinking for an experiment, why not cut the end off one of those extra cords I ordered, unwire the NEMA L6-30P from the BGA unit, wire it up to the cord, plug the PSU into one of the servers, plug the cord into the PSU and see if it fires up?

According to HPE, it just won't start.   They didn't say it'd cause any damage or anything.   That way, I can just ease my mind, and then there's no doubts at all.....1400 watt PSUs....those plugs should have the correct gauge wire inside of them.

[IanB]

Yes, with North American setup.   But with the transformer I was going to purchase, I was under the impression if you connect L2 to ground there is no short.   I was under the impression that was the whole reason I needed to purchase that specific transformer that Mr. Crowley originally suggested, because of the single-pole breakers inside of the PDU that I was sold.   So L1 is the only hot wire, with ~240VAC in reference to ground or in reference to L2 (but only with that transformer Mr. Crowley suggested I purchase if I were to continue to keep the current PDU and wanted to maintain safety.)   That way, if one of the breakers tripped, it'd cut the path of L1, but L2 and N would still be active, but wouldn't be a danger.    I think you guys missed the part where I said the transformer that I was going to purchase and think that I'm talking about the transformer on the pole in North America.

With the transformer Mr. Crowley suggested I purchase if I were going to keep the PDU, there shouldn't be an L2 on the secondary side, if I understand everything correctly.   There's only an L1, an N, and an E.   With American transformers, yes, if we connect either L1 or L2 to ground, we get a direct short and the breaker (hopefully!) trips to protect us.   Or, with that transformer Mr. Crowley suggested I purchase if I were going to keep the PDU, on the PRIMARY side, if I connected L1 OR L2 to ground, we'd have a dead short and that'd be horrible and hopefully the double-pole breaker on the mains panel would protect us and trip.   But if we were to be doing that, we shouldn't be playing with electricity until we learned a lot more about it.

Broadly speaking this is correct--in theory. But in practice, if you installed the transformer Mr. Crowley suggested and created a secondary supply with a sub-panel, you would probably be getting into areas not routinely covered by the electrical code. You will be creating something that inspectors do not expect to see, and so they will be getting into difficult territory when trying to approve it. And the situation with your insurance company, should anything bad happen, would be similar. Bear in mind that insurance companies like finding ways not to pay claims...

So really the best strategy is to follow North American electrical practice as closely as possible, do everything to the letter of the code, and do not introduce strange and unfamiliar things into the system.

(Keep in mind that if you use the P9S13A that comes pre-fitted with an L6-30P plug, then all you have to do is to provide some correctly wired and installed 30 A circuits back to your breaker panel with L6-30R receptacles on the end of them for your PDUs to plug into. Everything after the receptacle will be off the shelf hardware designed for the North American market and all your inspector will have to do is to sign off on the L6-30R receptacles and circuits. Everything will be straightforward, recognizable, and to code. Your inspector will have an easy job and no worries.)

[IanB]

Anyway, when I ordered the plugs for all the equipment the PDU was going to power, I ordered a few extras, just for expansion later on and to have.   I came up with an idea.   I have that NEMA L6-30R wired up, and I wired the NEMA L6-30P myself for the BGA rework station.    I'm wondering if one of these servers could run with just one PSU, and I think it can right now, at least temporarily.    I'm thinking for an experiment, why not cut the end off one of those extra cords I ordered, unwire the NEMA L6-30P from the BGA unit, wire it up to the cord, plug the PSU into one of the servers, plug the cord into the PSU and see if it fires up?

Yes, you can plug a server PSU directly into an L6-30 receptacle as long as you have a correctly wired power cord between the PSU and the receptacle. As long as the PSU is designed to accept 240 V AC it should work fine.

[Spork Schivago]

Yes, with North American setup.   But with the transformer I was going to purchase, I was under the impression if you connect L2 to ground there is no short.   I was under the impression that was the whole reason I needed to purchase that specific transformer that Mr. Crowley originally suggested, because of the single-pole breakers inside of the PDU that I was sold.   So L1 is the only hot wire, with ~240VAC in reference to ground or in reference to L2 (but only with that transformer Mr. Crowley suggested I purchase if I were to continue to keep the current PDU and wanted to maintain safety.)   That way, if one of the breakers tripped, it'd cut the path of L1, but L2 and N would still be active, but wouldn't be a danger.    I think you guys missed the part where I said the transformer that I was going to purchase and think that I'm talking about the transformer on the pole in North America.

With the transformer Mr. Crowley suggested I purchase if I were going to keep the PDU, there shouldn't be an L2 on the secondary side, if I understand everything correctly.   There's only an L1, an N, and an E.   With American transformers, yes, if we connect either L1 or L2 to ground, we get a direct short and the breaker (hopefully!) trips to protect us.   Or, with that transformer Mr. Crowley suggested I purchase if I were going to keep the PDU, on the PRIMARY side, if I connected L1 OR L2 to ground, we'd have a dead short and that'd be horrible and hopefully the double-pole breaker on the mains panel would protect us and trip.   But if we were to be doing that, we shouldn't be playing with electricity until we learned a lot more about it.

Broadly speaking this is correct--in theory. But in practice, if you installed the transformer Mr. Crowley suggested and created a secondary supply with a sub-panel, you would probably be getting into areas not routinely covered by the electrical code. You will be creating something that inspectors do not expect to see, and so they will be getting into difficult territory when trying to approve it. And the situation with your insurance company, should anything bad happen, would be similar. Bear in mind that insurance companies like finding ways not to pay claims...

So really the best strategy is to follow North American electrical practice as closely as possible, do everything to the letter of the code, and do not introduce strange and unfamiliar things into the system.

(Keep in mind that if you use the P9S13A that comes pre-fitted with an L6-30P plug, then all you have to do is to provide some correctly wired and installed 30 A circuits back to your breaker panel with L6-30R receptacles on the end of them for your PDUs to plug into. Everything after the receptacle will be off the shelf hardware designed for the North American market and all your inspector will have to do is to sign off on the L6-30R receptacles and circuits. Everything will be straightforward, recognizable, and to code. Your inspector will have an easy job and no worries.)

Yes, I realize that, and that's why I was really upset when, after my exec talked to the techs, and after the power analysis, they claimed they didn't make a PDU that would power the PSU that worked in North America (which is just B.S. if you ask me).    I found an old power cord for a PC.   I saved them when I worked on it.   Three 16 gauge wires.   That should be able to handle the current running through the L1 and L2 of the NEMA L6-30R I'll be plugging it into.   Should be hard to wire up.   I'd feel a bit more comfortable with 12 gauge wire.   I'll see if I can find anymore.

[IanB]

Yes, I realize that, and that's why I was really upset when, after my exec talked to the techs, and after the power analysis, they claimed they didn't make a PDU that would power the PSU that worked in North America (which is just B.S. if you ask me).    I found an old power cord for a PC.   I saved them when I worked on it.   Three 16 gauge wires.   That should be able to handle the current running through the L1 and L2 of the NEMA L6-30R I'll be plugging it into.   Should be hard to wire up.   I'd feel a bit more comfortable with 12 gauge wire.   I'll see if I can find anymore.

Well the P9S13A can handle 24 amps at 240 volts (5760 W), which is (I think) the maximum continuous load allowed on a 30 amp circuit by the electrical code. So if you need more than 24 amps to run all your equipment you need more than one 30 amp circuit from the breaker panel and more than one PDU. Using a different PDU will not allow you to take more than 5.7 kW from your 30 amp circuit and still comply with code.

[Spork Schivago]

The three 16-gauge should be fine.   The wires that come with the PSU have three 17-gauge.   Unless those cords really are made for 240VAC running down L1...

How would I calculate the current draw that the PSU will be pulling from the NEMA receptacle for each wire?    Would it be 1400 watts / 120 volts or would it be 700 watts / 120 volts?

Or would it just be 1400 watts / 240 volts?   I'd think not the second, because L1 and L2 will each carry 120V.   But then again, we're still dealing with 240V so the current overall shouldn't change....but for the individual conductors, do we treat L1 and L2 as just having 240V total between them and the current draw per conductor (in the physical plug) will be roughly 5.9 amps, or would be roughly 11.7 amps?

[Spork Schivago]

Yes, I realize that, and that's why I was really upset when, after my exec talked to the techs, and after the power analysis, they claimed they didn't make a PDU that would power the PSU that worked in North America (which is just B.S. if you ask me).    I found an old power cord for a PC.   I saved them when I worked on it.   Three 16 gauge wires.   That should be able to handle the current running through the L1 and L2 of the NEMA L6-30R I'll be plugging it into.   Should be hard to wire up.   I'd feel a bit more comfortable with 12 gauge wire.   I'll see if I can find anymore.

Well the P9S13A can handle 24 amps at 240 volts (5760 W), which is (I think) the maximum continuous load allowed on a 30 amp circuit by the electrical code. So if you need more than 24 amps to run all your equipment you need more than one 30 amp circuit from the breaker panel and more than one PDU. Using a different PDU will not allow you to take more than 5.7 kW from your 30 amp circuit and still comply with code.

Right.   We will be drawing more than 5.7 kW from the server, therefore, we need at least 2 PDUs.

[Bratster]

The three 16-gauge should be fine.   The wires that come with the PSU have three 17-gauge.   Unless those cords really are made for 240VAC running down L1...

How would I calculate the current draw that the PSU will be pulling from the NEMA receptacle for each wire?    Would it be 1400 watts / 120 volts or would it be 700 watts / 120 volts?

Or would it just be 1400 watts / 240 volts?   I'd think not the second, because L1 and L2 will each carry 120V.   But then again, we're still dealing with 240V so the current overall shouldn't change....but for the individual conductors, do we treat L1 and L2 as just having 240V total between them and the current draw per conductor (in the physical plug) will be roughly 5.9 amps, or would be roughly 11.7 amps?

1400w/240v

So just under 6 amps.

Sent from my Moto x4 using Tapatalk

[Monkeh]

The three 16-gauge should be fine.   The wires that come with the PSU have three 17-gauge.   Unless those cords really are made for 240VAC running down L1...

How would I calculate the current draw that the PSU will be pulling from the NEMA receptacle for each wire?    Would it be 1400 watts / 120 volts or would it be 700 watts / 120 volts?

Or would it just be 1400 watts / 240 volts?   I'd think not the second, because L1 and L2 will each carry 120V.   But then again, we're still dealing with 240V so the current overall shouldn't change....but for the individual conductors, do we treat L1 and L2 as just having 240V total between them and the current draw per conductor (in the physical plug) will be roughly 5.9 amps, or would be roughly 11.7 amps?

They don't each carry 120V. There is 240V between them and that is all there is to it. The two wires make the circuit so the current running through them will be equal.

You won't be hitting the full power draw anyway. Assemble your lead for this test (only. it won't be suitable for continued use as the breaker protecting it is rather too large), and give it a go. It'll be fine, it'll power up, it will complain about lack of redundant supplies.

We will be drawing more than 5.7 kW from the server, therefore, we need at least 2 PDUs.

I really hope you don't mean one server.

Also remember they use redundant supplies and you're very unlikely to draw the full 1400W from a single machine.

[IanB]

How would I calculate the current draw that the PSU will be pulling from the NEMA receptacle for each wire?

I posted the specs in the table above (post #208). The nominal current draw at full load at 240 V will be 6.5 A. Look at line 5 of the PSU specification table. However, it won't be running at full load, so the current will be less than this. Any ordinary power cord can carry 6 amps for test purposes.

Would it be 1400 watts / 120 volts or would it be 700 watts / 120 volts?

Or would it just be 1400 watts / 240 volts?   I'd think not the second, because L1 and L2 will each carry 120V.   But then again, we're still dealing with 240V so the current overall shouldn't change....but for the individual conductors, do we treat L1 and L2 as just having 240V total between them and the current draw per conductor (in the physical plug) will be roughly 5.9 amps, or would be roughly 11.7 amps?

I thought we had been through this. There is no 120 V. There is only 240 V. There is no 120 V. It is 240 V. Please try to remember this.

[Spork Schivago]

The three 16-gauge should be fine.   The wires that come with the PSU have three 17-gauge.   Unless those cords really are made for 240VAC running down L1...

How would I calculate the current draw that the PSU will be pulling from the NEMA receptacle for each wire?    Would it be 1400 watts / 120 volts or would it be 700 watts / 120 volts?

Or would it just be 1400 watts / 240 volts?   I'd think not the second, because L1 and L2 will each carry 120V.   But then again, we're still dealing with 240V so the current overall shouldn't change....but for the individual conductors, do we treat L1 and L2 as just having 240V total between them and the current draw per conductor (in the physical plug) will be roughly 5.9 amps, or would be roughly 11.7 amps?

1400w/240v

So just under 6 amps.

Sent from my Moto x4 using Tapatalk

Even though L1 and L2 are each 120VAC in reference to ground?    Just wanted to make sure.

Now one thing I will mention, the cord I'm sacrificing is NOT one of the cords that came with the PSUs and does NOT have the four pads on the bottom of it.   So I won't be plugging into those 4 pads at all, I'll just be by-passing them, but that shouldn't be an issue I wouldn't think for the simple fact that my PDU is NOT an "Intelligent" PDU and does not have the four pads per input....those four pads I believe are ONLY used for the Intelligent PDUs.

[Bratster]

See the post right above your reply, stop thinking about 120 volts. Your load is 240 volts.
The ground wire carries no current it is only for safety.

Sent from my Moto x4 using Tapatalk

[Spork Schivago]

The three 16-gauge should be fine.   The wires that come with the PSU have three 17-gauge.   Unless those cords really are made for 240VAC running down L1...

How would I calculate the current draw that the PSU will be pulling from the NEMA receptacle for each wire?    Would it be 1400 watts / 120 volts or would it be 700 watts / 120 volts?

Or would it just be 1400 watts / 240 volts?   I'd think not the second, because L1 and L2 will each carry 120V.   But then again, we're still dealing with 240V so the current overall shouldn't change....but for the individual conductors, do we treat L1 and L2 as just having 240V total between them and the current draw per conductor (in the physical plug) will be roughly 5.9 amps, or would be roughly 11.7 amps?

They don't each carry 120V. There is 240V between them and that is all there is to it. The two wires make the circuit so the current running through them will be equal.

You won't be hitting the full power draw anyway. Assemble your lead for this test (only. it won't be suitable for continued use as the breaker protecting it is rather too large), and give it a go. It'll be fine, it'll power up, it will complain about lack of redundant supplies.

We will be drawing more than 5.7 kW from the server, therefore, we need at least 2 PDUs.

I really hope you don't mean one server.

Also remember they use redundant supplies and you're very unlikely to draw the full 1400W from a single machine.

I gotcha.   Gonna wire it up and see what happens.   Wish me luck!   Broke my DMM (just the stand).   Knocked it over when I was looking for something.   That sucks.   Had that thing since I was a kid.   It was expensive at the time, but maybe I can buy a used unit to replace the stand.

[IanB]

Even though L1 and L2 are each 120VAC in reference to ground?    Just wanted to make sure.

Let's try this a different way. There are two wires, L1 and L2. Your multimeter has two probes, red and black. There are only two ways you can connect your meter probes to L1 and L2: either red-L1 and black-L2, or red-L2 and black-L1. Either way the meter will read 240 V AC. There are no other ways you can connect a meter to 2 wires, therefore there is no way to get a voltage other than 240 V from two wires.

If you had three wires there are more options, but since there are only two wires only one voltage is possible. You cannot get more than one voltage from 2 wires (other than zero volts by leaving one or both wires disconnected).

Whenever you are thinking about this you must ignore the ground wire as it is not allowed to carry current and must not be part of a circuit. If ever your electrical inspector finds the ground wire as part of a circuit you will fail inspection. The ground wire is forbidden to be used for anything except safety.

[Spork Schivago]

See the post right above your reply, stop thinking about 120 volts. Your load is 240 volts.
The ground wire carries no current it is only for safety.

Sent from my Moto x4 using Tapatalk

I actually wasn't thinking about 120VAC.   I had successfully calculated the load to be around 5.6 amp with a full load (which we won't have, because the upgrades aren't installed yet), so I'm good.   I just wanted to have you guys double check my work and provide a few scenarios.   I said, "...we're still dealing with 240V so the current overall shouldn't change...".   I just type how my mind thinks sometimes.   Gotta work on that I guess.

[Spork Schivago]

Even though L1 and L2 are each 120VAC in reference to ground?    Just wanted to make sure.

Let's try this a different way. There are two wires, L1 and L2. Your multimeter has two probes, red and black. There are only two ways you can connect your meter probes to L1 and L2: either red-L1 and black-L2, or red-L2 and black-L1. Either way the meter will read 240 V AC. There are no other ways you can connect a meter to 2 wires, therefore there is no way to get a voltage other than 240 V from two wires.

If you had three wires there are more options, but since there are only two wires only one voltage is possible. You cannot get more than one voltage from 2 wires (other than zero volts by leaving one or both wires disconnected).

Whenever you are thinking about this you must ignore the ground wire as it is not allowed to carry current and must not be part of a circuit. If ever your electrical inspector finds the ground wire as part of a circuit you will fail inspection. The ground wire is forbidden to be used for anything except safety.

That last part is still something I gotta get used to, because in DC, we use the ground for more than just safety.   It's the ground that completes the circuit.   So I have to keep switching back and fourth in my head between AC and DC (I'm currently working at the moment, and while the compiler is running, I bounce back here, then when it's done, I upload the code to a BGA component and watch my logic analyzer for a bit and then come back here, bounce back there, etc).

[IanB]

That last part is still something I gotta get used to, because in DC, we use the ground for more than just safety.   It's the ground that completes the circuit.   So I have to keep switching back and fourth in my head between AC and DC (I'm currently working at the moment, and while the compiler is running, I bounce back here, then when it's done, I upload the code to a BGA component and watch my logic analyzer for a bit and then come back here, bounce back there, etc).

Actually, no, that's not really true. Ground is used interchangeably with two different meanings, but really there should be two different words used. (In the UK there actually are two different words, ground and earth.)

The first meaning of ground is as the current return path, or the reference point for voltages. This could be called "signal ground" in some contexts. This is what ground means in the UK and what you may be familiar with in low voltage DC circuits.

The second meaning of ground is for electrical safety, as a protection mechanism. This ground must not carry current and must not be used in circuits. This is what earth means in the UK (sometimes called "protective earth" or "PE").

[Spork Schivago]

That last part is still something I gotta get used to, because in DC, we use the ground for more than just safety.   It's the ground that completes the circuit.   So I have to keep switching back and fourth in my head between AC and DC (I'm currently working at the moment, and while the compiler is running, I bounce back here, then when it's done, I upload the code to a BGA component and watch my logic analyzer for a bit and then come back here, bounce back there, etc).

Actually, no, that's not really true. Ground is used interchangeably with two different meanings, but really there should be two different words used. (In the UK there actually are two different words, ground and earth.)

The first meaning of ground is as the current return path, or the reference point for voltages. This could be called "signal ground" in some contexts. This is what ground means in the UK and what you may be familiar with in low voltage DC circuits.

The second meaning of ground is for electrical safety, as a protection mechanism. This ground must not carry current and must not be used in circuits. This is what earth means in the UK (sometimes called "protective earth" or "PE").

In DC, we have a bunch of words, depending on what you're dealing with, that essentially serve the same purpose.   For example, the term High-Voltage Differential Signaling could mean many things, depending on who you're talking to or what you're dealing with.   But then you have Low-Voltage Differential Signaling, which to my recollection, is actually a standard set by TIA/EIA.   And then, you gotta be careful about the low-voltage signal line sharing the same ground as a DC power supply line because you can end up getting some current returning to ground.   It's a bit of a different world than AC.   I mean, there's similarities it seems, but AC now seems kind of simple compared to DC.   I just never had the time to properly learn it.

Anyway, I hooked the BGA rework station backup, the server powered up just fine like you guys were saying, so I have to admit that I was wrong.   I will send an email to my Account Executive to see about a return.   We still have the box, which is important, because the PDU hasn't failed or anything.   So it doesn't get warranted and needs the original packaging or it'd be refused.   We've had it for a bit of time now because we were going by what HPE techs said and thought we really needed the transformer for whatever reason.   But I think this gives us some leverage to work with if they don't want to accept it because of the time.   As I see it, they're in the wrong here, not me.   What worries me is I installed it in the rack.   That's where I'm going to have issues, if there are any issues.

I'll remove it and see if they can tell it's been installed.   I don't like to lie, I don't think it's right, so if I'm asked, I'll tell them, yes, I installed it.   If they don't accept the return, I guess it's time to start thinking about dropping HPE and maybe switching to Lenovo.   I've heard their server side equipment is pretty decent.

[Gregg]

We gotta back up the train here a bit.   I understand the purpose of the neutral and ground in the house.   If we have a short, we want that current and voltage to go to the path of least resistance, hopefully back to the breaker, to trip it

OK, let’s try to go back to some basics.
I assume you know how a transformer works; I suggest you grab some paper and draw the circuits out for yourself as you follow along; visual reinforcement is a great learning aid and along the way you might have the “Ah Ha” moment where this becomes clear. 
Vin / Vout = Turns in / Turns out and the current capacity is more or less determined by winding size
If you have a 120VAC primary transformer with a 24VAC secondary, you get 24VAC output
Suppose you put this transformer on a metal chassis like old radios etc. and you plug it into the wall with a standard grounded 3 pin plug so that L1 is fused and connected to either wire of the primary and the neutral is connected to the other lead of the primary with the ground connected to the chassis.  All is well with the circuit here; the primary is a completed circuit via the neutral and L1.   

If one of the primary windings anywhere along the coils faults to the chassis, the ground that previously carried zero current suddenly carries the fault current back to the house breaker panel where it completes the circuit via the ground to neutral tie I showed in the previous post and the fuse should blow.   

At this point of the discussion, the secondary winding is completely isolated from the primary.  Let’s call them X1 and X2.  You could connect either lead to the chassis (which is grounded) and nothing would happen; no current would flow.  The other lead of the secondary would then be 24VAC to the chassis, often called chassis ground in this case which is also referenced to earth ground via the 3 prong plug. 

Let’s assume neither X1 nor X2 secondary winding are connected to the chassis for this paragraph.  If you take two 12 volt lamps of the same wattage in series and connect them to X1 and X2, they will both light equally.  They have the same resistance.  If you connect the midpoint between these two lamps to the chassis, nothing bad will happen, it is still isolated and, current will not flow to the chassis.  Now, connect a 5 watt and 10 watt both 12volt lamps in series and connect them to X1 and X2.  The 5 watt lamp gets very bright in a hurry and goes poof; the 10 watt lamp barely glows until the circuit goes open with the failure of the 5 watt lamp; this happens the same if the midpoint is connected to the chassis because it is isolated.

Now let’s change things a bit and connect a wire to the center of the secondary windings, a true center tap I’ll call C. Nothing on the secondary is connected to the chassis at this point.
X1 to X2 is still 24VAC
X1 to C is 12VAC
X2 to C is 12VAC 
Now, connect a 5 watt and 10 watt both 12volt lamps in series and connect them to X1 and X2 BUT with the midpoint connected to C.
They both light with their respective brightness and wattage; the 5 watt one doesn’t go poof!  The unbalanced extra 5 watts used by the 10 watt lamp is carried back to the transformer center tap C.  The 5 watt lamp and half of the 10 watt lamp’s current are the same as two 5 watt lamps in series without the midpoint connected to the transformer; the imbalanced 5 watts for the 10 watt lamp returns back to the transformer via the center tap.

Now if we connect the center tap C to the chassis (which is referenced to earth ground as previously stated) there is no harm, no foul and no current flow between C and the chassis.
And when we repeat the experiment, the results are the same.  The wire from the midpoint of the lamp back to C still carries the 5 watts; chassis ground is just a reference.

The transformer at the pole though....you said, "For instance, if you had 30 amps load on the 120volt side from L1 to neutral and 20 amps load on the other side from L2 to neutral, the neutral conductor would carry the 10 amp difference back to the transformer."

Yes, that is true as in the lamp scenario above; but to carry it further:  It would be very helpful for you to draw this on paper.
Suppose you have another transformer connected at the primary exactly as above but with two 12VAC secondary windings, completely isolated from each other.  So as not to confuse this with the above the first winding leads will be labeled X3 and X4; the other will be X5 and X6.
If you connect your 5 watt 12V lamp to X3 and X4 it will light; circuit completed.  If you then connect the 10 watt lamp to X5 and X6 it too will light; a completely separate circuit.  With both lamps on it you have 4 wires to the transformer secondary 
With the above 4 wire scenario in mind, if you connect X4 to X5 there will be 24VAC between X3 and X6; and the X4&X5 connection is the center tap and behaves EXACTLY the same as the single winding with the center tap mentioned above.  Only three wires are needed for your two lamps and the center tap only carries the imbalanced current.

On a side note, not relevant to this discussion, if you connect X3&X5 as well as X4&X6 both making two parallel windings (they have to be wound the same direction or phasing if you prefer) you will get 12VAC at double the current capacity. 

Where are these loads coming from?    Some place in the transformer, or in the house?   Why would there ever be an excess of current?   A 60 watt bulb will always draw 60 watt, even if you have it hooked to a 200-amp breaker.   So how could you ever have an excess of current?   Even if you were to directly wire hot to neutral or hot to ground, if neutral and ground are at 0V, wouldn't there be an instant volt drop where they connected and a lot of heat generated?

The loads mentioned are hypothetical.  Every time you turn on a light or 120 volt appliance the situation changes.  Think of the transformer as the source of your power however you want to think about it; volts, amps, watts etc. If you have a 60 watt bulb connected from L1 to neutral and you turn on your 1200 watt 120V toaster connected from L2 to neutral, there will be an imbalance.  The 200 amp breaker doesn’t care unless it sees an overload on one or both legs L1 and/or L2.  The breaker doesn’t see the neutral, nor does it have to as the neutral amps can never be greater than either L1 or L2 in normal circumstances. 
If you directly wire L1 or L2 to neutral or to a properly connected ground it will go boom.  If you can stand them, Electroboom’s YouTube videos are happy to demonstrate this so you don’t have to.
And to answer your question, there would be heat generated but it would be governed by the available voltage and current as well as the time before something (like the breaker or wire vaporizing) breaks the circuit.  If you turn off the breaker and connect line to neutral, the breaker should pop back off before any real damage is done and you won’t experience any real heating.
You would be better not thinking of ground and neutral as zero volts but as a reference point.  Zero volts is like absolute zero temperature, unattainable in real life but a good reference point.  Calling it ground or neutral is a lot more specific, purposeful and doesn’t mess with your head as much.

I had an old camaro and the ignition went bad.   I had to hot wire it.   I'd use the fuse panel.   I'd hook to a 12V source, then use a wire to tie into the fuse for the Ignition.   Then I'd hook into the 12V source and tie into the starter, but just long enough to get running.   One day, I was a little careless and grounded that 12V source.   The wire evaporated in my hand and left a white indent.   At first it didn't hurt, then it hurt real bad.   But there wasn't no excess current that just traveled safely back to the cells in the battery.   Wouldn't an excess current be called a short?

I guess you found out the hard way why it is called “hot wiring” a vehicle.  FYI a “short” is basically any unwanted return to source.  In your case the wire you were holding made a circuit from the +12VDC source (basically the battery or unfused path to the battery + terminal) to the engine block or chassis which are very well bonded to the – terminal of the battery.  A good car battery is easily capable of producing over 1000 amps at about 10 volts for a short time.  That is 10 kilowatts available but as your wire that is the weak part of the circuit heats up, its resistance goes up significantly which probably saved you from being burned a lot worse and / or welding something you didn’t want welded.  In the Camaro case the current wasn’t excess, it was just available from the source.  Your wire was the same as a filament in a headlamp as far as the battery was concerned; it was connected between the battery poles and the current took the path of least resistance in the newly made circuit.  The wire you used did have resistance, all wire does.  If you had used a really big wire, you could have blown up the battery. 

Also, how come our neutrals and grounds in the house are tied together?   Why can we not have it like the transformers on the poles where neutral is seperate from ground?   Actually, I probably could, couldn't I?   Outside, there's a grounding wire that's buried in the earth that hooks to the panel.   If I separated the ground and neutral buss-bars in the breaker panel, and made sure my ground buss-bar went to the grounding wire outside, and the neutral went back to the pole, I'd essentially have the same setup as the pole.   Someone in this thread mentioned in their house they'd never have the ground tied to the neutral.   But in every home I've seen, this is how it's always setup.   Is there any dangers to doing what I just described?

Neutrals and grounds are tied together for safety.  I think we have already discussed this.  In many cases water lines go through the ground, houses are built on slabs of concrete that when damp are pretty good conductors in terms of life safety.  If the neutral were not grounded, and wire does have some resistance as do wiring connections, there can be potential on the neutral conductor.  Grounding the neutral mitigates the possible severity of a person coming into contact with a neutral while grounded. 
The transformer on the pole for residential services in the USA almost always has the secondary neutral bonded to earth ground as near to the transformer as possible.  It is usually a fairly small (#8) bare wire that goes down the pole to the bottom.  The bare wire on the 3 wire drop from the pole to your house is the neutral conductor.
WHY on earth would you want to separate the ground form neutral in your house?  It would be a clear violation of the code.  It could put you and your family at a greater risk of shock.  The National Electric Code is revised every 3 years, is based on a lot of history of mishaps and contains the best reasonable ways to mitigate problems.  Look up ebay item 401538337928 it is a 2008 copy of the official NEC handbook for $18.  Just buy it, read through it and keep it for future reference.  The hardcover handbook has a lot of the code explained in real person English
Grounding and specifically proper grounding is a huge field in itself; there are power engineers that have made a career out of nothing but grounding.

[JustMeHere]

There are 240 sockets in the US with a wider prong.  They are for running large window AC units.   

I'd just splice together an adapter wire with the correct plug on each end.

[Spork Schivago]

Ah shit.   We might actually have to go for the transformer still.   The P9S16A's are actually cheaper than the P9S13A's.   We would actually be spending more money purchasing just one, let alone two.   Cost effectively, I think it'd be a hell of a lot cheaper to just wire up the transformer.

[james_s]

I do like the UK term "earth" for referring to what we typically refer to as "ground".

You could ignore the fact that it's AC all together and think of this in terms of DC. If you take a pair of D batteries and connect them end to end you'll have 3V from one end to another. Now pretend that they're concealed and you can't see the + and - markings, that's fine because that information is irrelevant since your hypothetical load doesn't care about polarity. Now take a wire connected to the joint in the middle between the two batteries and attach that to a stake in the ground, now you can call that point ground or earth of you like. Now between the two remaining wires you'll still have 3V, but if you measure between either one and ground you'll see 1.5V. If you connect either one to ground you'll have a short. In DC you'd call it +1.5V and -1.5V but what really matters is the relative potential between two points and since the polarity is constantly changing with AC it's simpler to refer to it as phase.

I don't know how it can get much simpler than this.

[james_s]

Ah shit.   We might actually have to go for the transformer still.   The P9S16A's are actually cheaper than the P9S13A's.   We would actually be spending more money purchasing just one, let alone two.   Cost effectively, I think it'd be a hell of a lot cheaper to just wire up the transformer.

Remember that a transformer that size will be expensive and it will burn up a non-trivial amount of power just sitting there.

I'm not familiar with the specific PDU's you're dealing with but I would be tempted to get a bunch of rack mount power strips and plug them into a row of standard 120V receptacles. You could easily install several dedicated 20A 120V circuits.

[IanB]

Ah shit.   We might actually have to go for the transformer still.   The P9S16A's are actually cheaper than the P9S13A's.   We would actually be spending more money purchasing just one, let alone two.   Cost effectively, I think it'd be a hell of a lot cheaper to just wire up the transformer.

Remember that the transformer suggested earlier by Richard Crowley is 7.5 kVA. If that were to be fully loaded that would draw 7500 VA / 240 V = 31.25 A.

Multiply that by 1.25 to get a continuous load rating (your server farm is a continuous load) and you get 39 A.

So you would need to provide a 40 amp circuit using the recommended 8-gauge wire to a 40 amp breaker in the panel.

You would not be able to run the transformer off an L6-30R receptacle, you would have to wire it in permanently.

Then you would have to wire up the secondary side of the transformer to your PDU. You probably don't want to just put a fly-lead on the secondary with an IEC receptacle on it, so you will need to source an appropriate commercial use breaker panel that supports 240 V line to neutral with single pole breakers, and then install wall mounted IEC receptacle(s) to plug your PDU into. And then you have to get it to pass inspection.

If you cost all that out, I think it might be cheaper just to buy the two new PDUs.

[james_s]

Especially when you can get used PDUs for peanuts on ebay.

[Spork Schivago]

We gotta back up the train here a bit.   I understand the purpose of the neutral and ground in the house.   If we have a short, we want that current and voltage to go to the path of least resistance, hopefully back to the breaker, to trip it

OK, let’s try to go back to some basics.
I assume you know how a transformer works; I suggest you grab some paper and draw the circuits out for yourself as you follow along; visual reinforcement is a great learning aid and along the way you might have the “Ah Ha” moment where this becomes clear. 
Vin / Vout = Turns in / Turns out and the current capacity is more or less determined by winding size
If you have a 120VAC primary transformer with a 24VAC secondary, you get 24VAC output
Suppose you put this transformer on a metal chassis like old radios etc. and you plug it into the wall with a standard grounded 3 pin plug so that L1 is fused and connected to either wire of the primary and the neutral is connected to the other lead of the primary with the ground connected to the chassis.  All is well with the circuit here; the primary is a completed circuit via the neutral and L1.   

If one of the primary windings anywhere along the coils faults to the chassis, the ground that previously carried zero current suddenly carries the fault current back to the house breaker panel where it completes the circuit via the ground to neutral tie I showed in the previous post and the fuse should blow.   

At this point of the discussion, the secondary winding is completely isolated from the primary.  Let’s call them X1 and X2.  You could connect either lead to the chassis (which is grounded) and nothing would happen; no current would flow.  The other lead of the secondary would then be 24VAC to the chassis, often called chassis ground in this case which is also referenced to earth ground via the 3 prong plug. 

Let’s assume neither X1 nor X2 secondary winding are connected to the chassis for this paragraph.  If you take two 12 volt lamps of the same wattage in series and connect them to X1 and X2, they will both light equally.  They have the same resistance.  If you connect the midpoint between these two lamps to the chassis, nothing bad will happen, it is still isolated and, current will not flow to the chassis.  Now, connect a 5 watt and 10 watt both 12volt lamps in series and connect them to X1 and X2.  The 5 watt lamp gets very bright in a hurry and goes poof; the 10 watt lamp barely glows until the circuit goes open with the failure of the 5 watt lamp; this happens the same if the midpoint is connected to the chassis because it is isolated.

Now let’s change things a bit and connect a wire to the center of the secondary windings, a true center tap I’ll call C. Nothing on the secondary is connected to the chassis at this point.
X1 to X2 is still 24VAC
X1 to C is 12VAC
X2 to C is 12VAC 
Now, connect a 5 watt and 10 watt both 12volt lamps in series and connect them to X1 and X2 BUT with the midpoint connected to C.
They both light with their respective brightness and wattage; the 5 watt one doesn’t go poof!  The unbalanced extra 5 watts used by the 10 watt lamp is carried back to the transformer center tap C.  The 5 watt lamp and half of the 10 watt lamp’s current are the same as two 5 watt lamps in series without the midpoint connected to the transformer; the imbalanced 5 watts for the 10 watt lamp returns back to the transformer via the center tap.

Now if we connect the center tap C to the chassis (which is referenced to earth ground as previously stated) there is no harm, no foul and no current flow between C and the chassis.
And when we repeat the experiment, the results are the same.  The wire from the midpoint of the lamp back to C still carries the 5 watts; chassis ground is just a reference.

The transformer at the pole though....you said, "For instance, if you had 30 amps load on the 120volt side from L1 to neutral and 20 amps load on the other side from L2 to neutral, the neutral conductor would carry the 10 amp difference back to the transformer."

Yes, that is true as in the lamp scenario above; but to carry it further:  It would be very helpful for you to draw this on paper.
Suppose you have another transformer connected at the primary exactly as above but with two 12VAC secondary windings, completely isolated from each other.  So as not to confuse this with the above the first winding leads will be labeled X3 and X4; the other will be X5 and X6.
If you connect your 5 watt 12V lamp to X3 and X4 it will light; circuit completed.  If you then connect the 10 watt lamp to X5 and X6 it too will light; a completely separate circuit.  With both lamps on it you have 4 wires to the transformer secondary 
With the above 4 wire scenario in mind, if you connect X4 to X5 there will be 24VAC between X3 and X6; and the X4&X5 connection is the center tap and behaves EXACTLY the same as the single winding with the center tap mentioned above.  Only three wires are needed for your two lamps and the center tap only carries the imbalanced current.

On a side note, not relevant to this discussion, if you connect X3&X5 as well as X4&X6 both making two parallel windings (they have to be wound the same direction or phasing if you prefer) you will get 12VAC at double the current capacity. 

Where are these loads coming from?    Some place in the transformer, or in the house?   Why would there ever be an excess of current?   A 60 watt bulb will always draw 60 watt, even if you have it hooked to a 200-amp breaker.   So how could you ever have an excess of current?   Even if you were to directly wire hot to neutral or hot to ground, if neutral and ground are at 0V, wouldn't there be an instant volt drop where they connected and a lot of heat generated?

The loads mentioned are hypothetical.  Every time you turn on a light or 120 volt appliance the situation changes.  Think of the transformer as the source of your power however you want to think about it; volts, amps, watts etc. If you have a 60 watt bulb connected from L1 to neutral and you turn on your 1200 watt 120V toaster connected from L2 to neutral, there will be an imbalance.  The 200 amp breaker doesn’t care unless it sees an overload on one or both legs L1 and/or L2.  The breaker doesn’t see the neutral, nor does it have to as the neutral amps can never be greater than either L1 or L2 in normal circumstances. 
If you directly wire L1 or L2 to neutral or to a properly connected ground it will go boom.  If you can stand them, Electroboom’s YouTube videos are happy to demonstrate this so you don’t have to.
And to answer your question, there would be heat generated but it would be governed by the available voltage and current as well as the time before something (like the breaker or wire vaporizing) breaks the circuit.  If you turn off the breaker and connect line to neutral, the breaker should pop back off before any real damage is done and you won’t experience any real heating.
You would be better not thinking of ground and neutral as zero volts but as a reference point.  Zero volts is like absolute zero temperature, unattainable in real life but a good reference point.  Calling it ground or neutral is a lot more specific, purposeful and doesn’t mess with your head as much.

I had an old camaro and the ignition went bad.   I had to hot wire it.   I'd use the fuse panel.   I'd hook to a 12V source, then use a wire to tie into the fuse for the Ignition.   Then I'd hook into the 12V source and tie into the starter, but just long enough to get running.   One day, I was a little careless and grounded that 12V source.   The wire evaporated in my hand and left a white indent.   At first it didn't hurt, then it hurt real bad.   But there wasn't no excess current that just traveled safely back to the cells in the battery.   Wouldn't an excess current be called a short?

I guess you found out the hard way why it is called “hot wiring” a vehicle.  FYI a “short” is basically any unwanted return to source.  In your case the wire you were holding made a circuit from the +12VDC source (basically the battery or unfused path to the battery + terminal) to the engine block or chassis which are very well bonded to the – terminal of the battery.  A good car battery is easily capable of producing over 1000 amps at about 10 volts for a short time.  That is 10 kilowatts available but as your wire that is the weak part of the circuit heats up, its resistance goes up significantly which probably saved you from being burned a lot worse and / or welding something you didn’t want welded.  In the Camaro case the current wasn’t excess, it was just available from the source.  Your wire was the same as a filament in a headlamp as far as the battery was concerned; it was connected between the battery poles and the current took the path of least resistance in the newly made circuit.  The wire you used did have resistance, all wire does.  If you had used a really big wire, you could have blown up the battery. 

Also, how come our neutrals and grounds in the house are tied together?   Why can we not have it like the transformers on the poles where neutral is seperate from ground?   Actually, I probably could, couldn't I?   Outside, there's a grounding wire that's buried in the earth that hooks to the panel.   If I separated the ground and neutral buss-bars in the breaker panel, and made sure my ground buss-bar went to the grounding wire outside, and the neutral went back to the pole, I'd essentially have the same setup as the pole.   Someone in this thread mentioned in their house they'd never have the ground tied to the neutral.   But in every home I've seen, this is how it's always setup.   Is there any dangers to doing what I just described?

Neutrals and grounds are tied together for safety.  I think we have already discussed this.  In many cases water lines go through the ground, houses are built on slabs of concrete that when damp are pretty good conductors in terms of life safety.  If the neutral were not grounded, and wire does have some resistance as do wiring connections, there can be potential on the neutral conductor.  Grounding the neutral mitigates the possible severity of a person coming into contact with a neutral while grounded. 
The transformer on the pole for residential services in the USA almost always has the secondary neutral bonded to earth ground as near to the transformer as possible.  It is usually a fairly small (#8) bare wire that goes down the pole to the bottom.  The bare wire on the 3 wire drop from the pole to your house is the neutral conductor.
WHY on earth would you want to separate the ground form neutral in your house?  It would be a clear violation of the code.  It could put you and your family at a greater risk of shock.  The National Electric Code is revised every 3 years, is based on a lot of history of mishaps and contains the best reasonable ways to mitigate problems.  Look up ebay item 401538337928 it is a 2008 copy of the official NEC handbook for $18.  Just buy it, read through it and keep it for future reference.  The hardcover handbook has a lot of the code explained in real person English
Grounding and specifically proper grounding is a huge field in itself; there are power engineers that have made a career out of nothing but grounding.

Thank you for your explanation but in all honesty, I was so tired from lack of sleep last night, I don't even remember writing the post.   I had some stuff to finish and I think when I called it a night, it was over 36 hours of me being awake, it was around 0300 but after getting into bed, I wasn't able to actually fall asleep until 0600.   For the Official NEC, you don't need to waste your money on a copy of the book.   You can do what I do, just go to https://www.nfpa.org/NEC    and click on Free online access to the NEC® and other electrical standards.   Then you're not getting the outdated standards, it also lists the changes from the previous edition to the latest (the latest is 2017 I believe), and best of all, it's totally free.   You just need to sign up for an account.   There are options to download a digital copy (for money) or purchase an actual physical copy (for money), but you don't need to do that to get access.  You can browse the entire 2017 NEC for free using that site.

When I question something (for example, what wire type do I need in the basement, can I drill holes through the first floor floor joists and run the wire or should I staple it, do I need to use the plastic staples, etc), I just head there, login, and check it up.   It's extremely handy.

After reading what I wrote, I think maybe what I was thinking was having an isolated ground from neutral.   I dunno why in earth I would want that.   I do have a need for an isolation transformer for a couple DUTs, so maybe that's where it came from?   I dunno.   Usually, I try to be in bed by 2100 ~ 2200, but sometimes, there's deadlines I have to meet, and I run behind so I have to stay up longer than I like.    I know I could have slept a lot longer today but I had my wife wake me up at 1100 so I could get some work done.

Anyway, thank you, and everyone else, for helping me understand everything properly now!   I've sent the email to my Account Executive to see where we stand, but because of the price tag actually being more for the North American version (with providing almost half of the version I currently have), I might just still buy the transformer.

As IanB said though, that might throw off the inspector.   So I'll first see what my Account Executive says and on Monday, while I'm waiting for a response, I'll call the local code enforcer.   I got his cell number but I don't want to disturb him on the weekend.   We're not buddy buddy kinda thing, you know?   I'll see if he'd recommend against the 240:240 transformer.

Little bit a sleep and it suddenly makes perfect sense how to wire it up and everything.   I don't know why I couldn't grasp it the other day.   Thanks though.

[Spork Schivago]

I do like the UK term "earth" for referring to what we typically refer to as "ground".

You could ignore the fact that it's AC all together and think of this in terms of DC. If you take a pair of D batteries and connect them end to end you'll have 3V from one end to another. Now pretend that they're concealed and you can't see the + and - markings, that's fine because that information is irrelevant since your hypothetical load doesn't care about polarity. Now take a wire connected to the joint in the middle between the two batteries and attach that to a stake in the ground, now you can call that point ground or earth of you like. Now between the two remaining wires you'll still have 3V, but if you measure between either one and ground you'll see 1.5V. If you connect either one to ground you'll have a short. In DC you'd call it +1.5V and -1.5V but what really matters is the relative potential between two points and since the polarity is constantly changing with AC it's simpler to refer to it as phase.

I don't know how it can get much simpler than this.

Yeah, I don't know how it could get simpler either or why your posting that.   I definitely understand it now.   Last night, I just didn't have any sleep, so maybe that was why I had a hard time grasping it?   I know my wife has mentioned some problems to the docs about my memory.   She goes to the neurologist with me and a few other appointments.   She says there's times that people that I know real well seem to disappear from my memory.   It's just not people, but time as well.   Sometimes, I guess I lose a year or two or can't remember my birthday.   But what's odd, I can't ever remember not being able to remember stuff.   So, it's like some memories are isolated from others and when I cannot remember my best friend, for example, I might remember something that I can't remember now, but when I can remember my best friend, that something is gone and cannot be reached!

They're having me do these exercises, brain ones, that's supposed to help my brain find new pathways.   In a way, the brain is much like the circuit boards we work on I guess, and what do you do when you have a burned out trace?   You can run a jumper wire or essentially, find another way for the electrons to flow.   I guess the brain works similarly.   If someone has a stroke, they have to sometimes "reteach" their mind how do things that it used to know, like walk.   My issue isn't so much with walking.   The damage I sustained affects the prefrontal cortex and for some reason, there are holes there, or legions.   What is bad, they're spreading and I have to go to some two week hospital thing where they monitor me and try to stress me out to try and figure out why they're spreading.    I have the global volume loss of T2 white matter (something along those lines), where she says I'm losing brain function.   Anyway, exercising the brain is supposed to help and my wife is supposed to "quiz" me every day.   What did you eat for breakfast?  What day is it?   What TV show were we just watching?   What day is it?   What did you eat for breakfast?   What did you eat for lunch?   Stuff like that.

[Spork Schivago]

Ah shit.   We might actually have to go for the transformer still.   The P9S16A's are actually cheaper than the P9S13A's.   We would actually be spending more money purchasing just one, let alone two.   Cost effectively, I think it'd be a hell of a lot cheaper to just wire up the transformer.

Remember that a transformer that size will be expensive and it will burn up a non-trivial amount of power just sitting there.

I'm not familiar with the specific PDU's you're dealing with but I would be tempted to get a bunch of rack mount power strips and plug them into a row of standard 120V receptacles. You could easily install several dedicated 20A 120V circuits.

Transformer is actually cheaper than the PDU I believe, but I haven't gotten the quote, but you do bring up a very important part that I keep on thinking about.   How efficient will this transformer be?   Someone I think referred to it as a hot piece of metal hanging on the wall.   To me, that means it won't be very efficient at all.   In the end, maybe the separate North American P9S13A's would be financially cheaper than the transformers power loss that shows up on the electric bill...In the long run, the P9S13A's are probably the less expensive way to go.   And the best part, I'd get the redundancy which is something we need eventually.   If I can get that now, that's one less thing to worry about later on.

[IanB]

So you would need to provide a 40 amp circuit using the recommended 8-gauge wire to a 40 amp breaker in the panel.

And you would be running your whole system off one 40 amp circuit, with no redundancy. If that breaker tripped for any reason then everything would shut down.

[Spork Schivago]

Ah shit.   We might actually have to go for the transformer still.   The P9S16A's are actually cheaper than the P9S13A's.   We would actually be spending more money purchasing just one, let alone two.   Cost effectively, I think it'd be a hell of a lot cheaper to just wire up the transformer.

Remember that the transformer suggested earlier by Richard Crowley is 7.5 kVA. If that were to be fully loaded that would draw 7500 VA / 240 V = 31.25 A.

Multiply that by 1.25 to get a continuous load rating (your server farm is a continuous load) and you get 39 A.

So you would need to provide a 40 amp circuit using the recommended 8-gauge wire to a 40 amp breaker in the panel.

You would not be able to run the transformer off an L6-30R receptacle, you would have to wire it in permanently.

Then you would have to wire up the secondary side of the transformer to your PDU. You probably don't want to just put a fly-lead on the secondary with an IEC receptacle on it, so you will need to source an appropriate commercial use breaker panel that supports 240 V line to neutral with single pole breakers, and then install wall mounted IEC receptacle(s) to plug your PDU into. And then you have to get it to pass inspection.

If you cost all that out, I think it might be cheaper just to buy the two new PDUs.

Yes, I've actually already thought about all of this and talked to the wife and said if we can send it back, I think we're going to send it back.   I told her we'd need the second panel, the wires for it, the breakers for it, we'd still need the receptacle, we'd still have to pay for inspection (which very well could fail, and then what?  Stuck with the PDU and still gotta buy two of the smaller units!)   Hopefully, they'll accept the return based on that's what HPE said I _needed_ and couldn't power it off my current panel, although, I was stupid, and didn't word it properly like I should have.   I called it 120-0-120 split-phase, which I shouldn't have done.   That's how I've been referring to it the whole time, even when they did the on-line power analysis.    That's my fault.   They probably didn't even know what the hell it was and just said in their minds, say what?   Hell no!

[Gregg]

Now that you say you understand the concept of 120/240 volt US power I am wondering why you want that expensive PDU.  In your basement, you hardly need remote switching and the PDU you chose doesn't seem to be able to meter the power.
If I were wiring 7.5 KW worth of servers in my basement, I would put a sub panel near them and run separate circuits to each major server and maybe separate breakers to each of the power supplies in those that have dual power supplies.  There is a lot of scalability and some redundancy in such a system and it costs a lot less in the long run.  You can then put very inexpensive power strips in the equipment racks and easily change everything as your service grows.  I would also wire in a wrap around bypass panel ahead of the panel to later install a UPS without interrupting any of the servers. 

[vk6zgo]

Now that you say you understand the concept of 120/240 volt US power I am wondering why you want that expensive PDU.  In your basement, you hardly need remote switching and the PDU you chose doesn't seem to be able to meter the power.
If I were wiring 7.5 KW worth of servers in my basement, I would put a sub panel near them and run separate circuits to each major server and maybe separate breakers to each of the power supplies in those that have dual power supplies.  There is a lot of scalability and some redundancy in such a system and it costs a lot less in the long run.  You can then put very inexpensive power strips in the equipment racks and easily change everything as your service grows.  I would also wire in a wrap around bypass panel ahead of the panel to later install a UPS without interrupting any of the servers.

That was my thought,too.

Most of the places I've worked, the power distribution was either designed  & built " in house", or was supplied as part of the equipment we were using, with the requirements specified when the EEs were ordering the system.
In both of the above methods, the power distribution setup could be "tailor made".

In the OP's case, it should be easy to customise the setup with discrete bits.

[IanB]

Now that you say you understand the concept of 120/240 volt US power I am wondering why you want that expensive PDU.  In your basement, you hardly need remote switching and the PDU you chose doesn't seem to be able to meter the power.
If I were wiring 7.5 KW worth of servers in my basement, I would put a sub panel near them and run separate circuits to each major server and maybe separate breakers to each of the power supplies in those that have dual power supplies.  There is a lot of scalability and some redundancy in such a system and it costs a lot less in the long run.  You can then put very inexpensive power strips in the equipment racks and easily change everything as your service grows.  I would also wire in a wrap around bypass panel ahead of the panel to later install a UPS without interrupting any of the servers.

Exactly. All you need is two or three dedicated 30 amp circuits feeding L6-30R receptacles, and then a power strip like one of these for each receptacle to feed your devices with dedicated C13/C14 power cords. You don't need an expensive PDU with features you are not using.

http://www.apc.com/shop/us/en/products/SADE-89TKZQ/P-AP7541

In each server you can put redundant power supplies fed from different circuits.

[Spork Schivago]

Now that you say you understand the concept of 120/240 volt US power I am wondering why you want that expensive PDU.  In your basement, you hardly need remote switching and the PDU you chose doesn't seem to be able to meter the power.
If I were wiring 7.5 KW worth of servers in my basement, I would put a sub panel near them and run separate circuits to each major server and maybe separate breakers to each of the power supplies in those that have dual power supplies.  There is a lot of scalability and some redundancy in such a system and it costs a lot less in the long run.  You can then put very inexpensive power strips in the equipment racks and easily change everything as your service grows.  I would also wire in a wrap around bypass panel ahead of the panel to later install a UPS without interrupting any of the servers.

There are reasons we need this PDU that I'd rather not go into.   Originally, we wanted a switched AND metered one, but HPE said they didn't make one that would work with our power supply.

I'm wondering though, now that we know they make mistakes, do any of you guys see a Switched AND metered horizontal 2U PDU that will work with my 120-0-120 split phase?

I feel comfortable saying it's not just power that we need the PDU to provide.   It's the features that come with it that are important.   And once we had this wired up, we were going to purchase another for redundancy.   Knowing now that we can definitely power those PSUs with our electricity, if we can send this back, we're definitely sending it back and at least purchasing two PDUs.   Hopefully we can split the load equally on both, but I'm really hoping just one can power the entire load.   That way, if one dies, we're notified and it automatically provides power to the broken PDU (depending on how it breaks) so our servers don't go down.

Money is always something to be conscious of, so even if we cannot send the PDU back, I think we're going to look into voiding the warranty and modifying it to work safely with our electricity, replace the European style plug with a nice NEMA L6-30P.   Someone else suggested that early on (at least the plug part).   We just have to wait to see what they say tomorrow.

Can you go a bit more in detail about the wrap-around bypass panel?    Eventually, the entire business will be on a seperate line, totally isolated from the residential stuff.   It'll have a dedicated panel (not a sub-panel), and a dedicated meter.   When we purchase the whole home generator, it'll have an ATS (Automatic Transfer Switch) that will have breakers in it.   We'll run them to both panels (well, have the company do it).   We still need a UPS.   We're slowly getting there though.   At least now, I can power my server again and install the upgrades (assuming the one 1400 watt can handle the entire load).   And then I can work on configuring that (which means another monthly bill for the VDA license).   But we're getting there.

[Spork Schivago]

Now that you say you understand the concept of 120/240 volt US power I am wondering why you want that expensive PDU.  In your basement, you hardly need remote switching and the PDU you chose doesn't seem to be able to meter the power.
If I were wiring 7.5 KW worth of servers in my basement, I would put a sub panel near them and run separate circuits to each major server and maybe separate breakers to each of the power supplies in those that have dual power supplies.  There is a lot of scalability and some redundancy in such a system and it costs a lot less in the long run.  You can then put very inexpensive power strips in the equipment racks and easily change everything as your service grows.  I would also wire in a wrap around bypass panel ahead of the panel to later install a UPS without interrupting any of the servers.

Exactly. All you need is two or three dedicated 30 amp circuits feeding L6-30R receptacles, and then a power strip like one of these for each receptacle to feed your devices with dedicated C13/C14 power cords. You don't need an expensive PDU with features you are not using.

http://www.apc.com/shop/us/en/products/SADE-89TKZQ/P-AP7541

In each server you can put redundant power supplies fed from different circuits.

That PDU would not work at all for us.   We ARE using features of the advanced PDU that we have, hence the reason we purchased it.   But it'd be real nice if we could find an equivalent to the P9S13As that was still a G2 but supported the Switched AND Metered, like we originally wanted, but HPE said no way without three-phase (for horizontal).   We have a 36-unit rack, and actually prefer the horizontal units.    We will buy double of what we need for the load, just to daisy chain them and have the redundancy.   But there's still a lot more expensive stuff we need to work on as well.

We need the UPS, we need the whole home generator, we need the dedicated panel, the dedicated meter, the auto-loading / rotating rack mountable tape backup unit, tapes, still need to finish wiring up the house, still haven't received the proper ends for the shielded ethernet (I don't want to go in on why we need shielded, so please don't ask!), we still have to finish the contract (almost done), finished the other one which gave us the rest of the money, so we're good for a bit on cash, but it's not going to pay for everything, still need to setup the VMs, reenable the VDA license, etc, etc, etc.    Time and money is always something I'm aware of.

There are features these PDUs, like the one we have, we need.   Features that don't come with normal power strips or power distribution units.

[Bratster]

You can't just change the plug out on the pdu that you have, you would have to completely change out all of the breakers and switching elements in side of it. Because it has to provide protection on both lines, not just one.

Changing the plug was talked about way back when everybody thought you had some mystery load.
A power distribution unit cannot be treated the same as a load, because it provides switching and protection.



As far as the multiple pdus goes you should have both of them running at the same time fed from different circuits obviously.
And then all of your servers that have redundant power supplies hook up one power supply plug into pdu number one and the other power supply plugged into pdu number two.

That way even if 1 pdu goes down completely your servers will still be running off the other pdu, as opposed to everything shutting down and you having to manually move things over.





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[IanB]

There are reasons we need this PDU that I'd rather not go into.   Originally, we wanted a switched AND metered one, but HPE said they didn't make one that would work with our power supply.

If HPE say that, they are saying they don't have a model that works in North America. That seems unlikely.

I'm wondering though, now that we know they make mistakes, do any of you guys see a Switched AND metered horizontal 2U PDU that will work with my 120-0-120 split phase?

You don't have a 120-0-120 split phase supply. You have a 240 V single phase supply.

Any PDU designed for the North American market that handles a 200-240 V AC single phase supply will work in your situation.

[Bratster]

240v single phase North American.

That last bit is important when you're looking for stuff so you don't find something like you already have that's intended for Europe.

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[Spork Schivago]

You can't just change the plug out on the pdu that you have, you would have to completely change out all of the breakers and switching elements in side of it. Because it has to provide protection on both lines, not just one.

Changing the plug was talked about way back when everybody thought you had some mystery load.
A power distribution unit cannot be treated the same as a load, because it provides switching and protection.

Yes, we are aware of this.   If it comes down to it though, we have some people on another forum, a real nice one, that are very knowledgeable and can help us modify it.   We are in fact discussing it there now, preparing, in case we do need to modify the PDU.   Trying to find the breakers that are used now, the proper breakers that will work, etc.   We can come close by physically matching the pics, but in the end, we'd need to crack her open and void the warranty to be certain.   And there's no sense doing that if we can send it back.

As far as the multiple pdus goes you should have both of them running at the same time fed from different circuits obviously.
And then all of your servers that have redundant power supplies hook up one power supply plug into pdu number one and the other power supply plugged into pdu number two.

That way even if 1 pdu goes down completely your servers will still be running off the other pdu, as opposed to everything shutting down and you having to manually move things over.

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I wasn't thinking like that, but that's a great idea and we'll do that.   Our servers, and the switch all have redundant PSUs.   The rest doesn't.   The servers and switch are important though, out of most of the equipment.

[Spork Schivago]

There are reasons we need this PDU that I'd rather not go into.   Originally, we wanted a switched AND metered one, but HPE said they didn't make one that would work with our power supply.

If HPE say that, they are saying they don't have a model that works in North America. That seems unlikely.

I'm wondering though, now that we know they make mistakes, do any of you guys see a Switched AND metered horizontal 2U PDU that will work with my 120-0-120 split phase?

You don't have a 120-0-120 split phase supply. You have a 240 V single phase supply.

Any PDU designed for the North American market that handles a 200-240 V AC single phase supply will work in your situation.

Would you like to help me try and find a Switched and Metered one that can handle a similar load or higher than the P9S13A's I was going to purchase?   The G2 series.   I don't think it was just a 3-phase thing, I think another issue was they were vertical and they didn't make one for our 36-unit one.   I really want to stick with the horizontal one, but if it came down to it, I would go for a vertical one, so long as it was for a 36-unit rack, not smaller.   If it gave us the Switched and Metered functionality, I'd be okay.   I couldn't just now, but I still haven't finished looking.   I was looking here:

https://www.hpe.com/us/en/product-catalog/servers/power-distribution-units/pip.models.power-distribution-units.1009830118.html

[Spork Schivago]

240v single phase North American.

That last bit is important when you're looking for stuff so you don't find something like you already have that's intended for Europe.

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See, I see things like 208V NA/JP with an L6-30P .   That's gotta be a typo.   It's single-phase.   That must be a 240VAC North American one.   But load capacity is only 5KVA.   We're already over that.   I don't remember what it was tallied up to, but I can find it real quick.   Without the BGA rework station (4800 watts), we're at 12,319 watts total, assuming everything's on at once, which it would never be.    So we could subtract some of that and we estimated around 6,360 watts.

[Bratster]

208v single phase is a valid voltage in the US. In a commercial environment with a 3-phase Supply that is what you would get Line to Line.

But since it is not using all three lines, it is not a three-phase device.

 Therefore it is a single phase device.



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[Spork Schivago]

208v single phase is a valid voltage in the US. In a commercial environment with a 3-phase Supply that is what you would get Line to Line.

But since it is not using all three lines, it is not a three-phase device.

 Therefore it is a single phase device.



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Yes, it's single-phase.   So is it a typo?   I know 208VAC is a valid option in the US, but I thought that was only for three-phase, not single-phase.

I wish we could do the Intelligent PDUs, but they don't offer something we need.   Which really sucks, and leaves us back with the switched, metered, or switched and metered.   The only things I can find for Switched and Metered are horizontal, and the only one I see provides less than 5KVA capacity....

[IanB]

It looks like the P9S15A is the only single phase option for switched and metered, and it is vertical mounting. It also only says on the specifications "200-208 V input". It doesn't say "200-240 V input". I do not know if 240 V would be a problem for it. HPE technical consultants would have to tell you the answer to that. If you talk to a salesperson they are likely to cover their ass and say "no"...

[Bratster]

You're only going to get 208 volts with a 3-phase Supply coming into the building.

But just because you have three phase doesn't mean every single device you have has to be three phase.

If something is only using two lines, and NOT all 3, then it is not called a three-phase device, it would be a single phase device.


Yes I know it's weird that even though there are two lines and if there was a third it would be called 3-phase so you would think it would be called two-phase, but no.

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[IanB]

See, I see things like 208V NA/JP with an L6-30P .  That's gotta be a typo.  It's single-phase.  That must be a 240VAC North American one.  But load capacity is only 5KVA.  We're already over that.

Why has it got to be a typo? I don't follow.

About the 5 kVA, that's a North American constraint, governed by the NEC.

If you have a 30 amp circuit the maximum continuous load permitted by the breaker and by the L6-30P is 24 amps. Now 208 V times 24 A is 5 kVA. That's the limit on one circuit, and since you would want one PDU per circuit, that's the limit on one PDU. (Since you have a 240 V supply the limit goes up to 5.7 kVA, but that's still your limit.)

So if your total system load is more than 5 kVA or so, then you need two or more 30 A circuits, and two or more PDUs. That's not only for redundancy, it is also an outcome of the National Electrical Code.

In summary, you can't put 7 or 8 kVA on one PDU, and neither would you want to.

[Spork Schivago]

It looks like the P9S15A is the only single phase option for switched and metered, and it is vertical mounting. It also only says on the specifications "200-208 V input". It doesn't say "200-240 V input". I do not know if 240 V would be a problem for it. HPE technical consultants would have to tell you the answer to that. If you talk to a salesperson they are likely to cover their ass and say "no"...

Yes, but even the tech people I talk to say no, it's only for 208VAC.    So it's listed as Single-Phase.   Is it possible in the US to get single phase 208VAC?   The tech documents for that PDU give the specs at what voltages it runs at and I think the max where 220VAC, so I don't think it's a typo there.   Don't quote me on the tech documents.   I'll have to check, but I got one of those co-workers here now and I gotta go and have him double check some of my work.   I'll be back later though.

[Spork Schivago]

See, I see things like 208V NA/JP with an L6-30P .  That's gotta be a typo.  It's single-phase.  That must be a 240VAC North American one.  But load capacity is only 5KVA.  We're already over that.

Why has it got to be a typo? I don't follow.

About the 5 kVA, that's a North American constraint, governed by the NEC.

If you have a 30 amp circuit the maximum continuous load permitted by the breaker and by the L6-30P is 24 amps. Now 208 V times 24 A is 5 kVA. That's the limit on one circuit, and since you would want one PDU per circuit, that's the limit on one PDU. (Since you have a 240 V supply the limit goes up to 5.7 kVA, but that's still your limit.)

So if your total system load is more than 5 kVA or so, then you need two or more 30 A circuits, and two or more PDUs. That's not only for redundancy, it is also an outcome of the National Electrical Code.

In summary, you can't put 7 or 8 kVA on one PDU, and neither would you want to.

The typo thing was a mistake by  me.   I didn't realize you didn't have to use all three-phases with three phase, so there's still stuff I'm learning about AC, which is good.   Well, this really sucks then, because I'm going to have to spend a lot of the cash I just made on 5KVA Switched PDUs.    Enough to cover my load, and then enough for redundancy <sigh>.   Maybe modifying the current PDU would be the better way to go.   A lot of work, I know, and it'd void warranty, but that just might be the best way to go about it.

I really gotta go though.   I'll be back later.

[IanB]

Yes, but even the tech people I talk to say no, it's only for 208VAC.  So it's listed as Single-Phase. Is it possible in the US to get single phase 208VAC?

Yes, 208 V AC single phase is a standard supply voltage in commercial premises.

Maybe modifying the current PDU would be the better way to go. A lot of work, I know, and it'd void warranty, but that just might be the best way to go about it.

Bear in mind that if you do that you would have to install a 40 amp circuit to plug it into and you wouldn't have any redundancy. But other than that it might work if fitted with 2-pole breakers.

[Gregg]

In a business environment every time you try to save money by not doing something correctly, Murphy’s Law gets reinforced big time.  Granted there are degrees of correctness, but blatant disregard for tried and true power wiring is not recommended. 
Things that you can get away with on the bench for short term testing seldom work out when put in service 24/7 unattended especially when it is your source of income.
You can’t afford pissed off customers, nobody wants a service that’s unreliable (even if it is cheaper than other options).

[Spork Schivago]

Yes, but even the tech people I talk to say no, it's only for 208VAC.  So it's listed as Single-Phase. Is it possible in the US to get single phase 208VAC?

Yes, 208 V AC single phase is a standard supply voltage in commercial premises.

Maybe modifying the current PDU would be the better way to go. A lot of work, I know, and it'd void warranty, but that just might be the best way to go about it.

Bear in mind that if you do that you would have to install a 40 amp circuit to plug it into and you wouldn't have any redundancy. But other than that it might work if fitted with 2-pole breakers.

I got a few seconds here, yes, I got the double-pole 40-amp breaker which I can return, if need be.   But I was thinking about what you said, "About the 5 kVA, that's a North American constraint, governed by the NEC."....would modifying the current PDU (which I do like because of the fact that it can handle higher loads) violate the NEC because it'd be using the 40-amp breaker?    I understand that 30-amp breakers the max would be 24-amp.   And I understand why.   But what I was saying was could HPE make a PDU for 240V North America that provides a higher load using something like double-pole 40-amp breakers?   Or is that against NEC?   I can check the NEC when I finish up here.   But once I'm done here, I want to get some work done for my start-up business.

[Spork Schivago]

In a business environment every time you try to save money by not doing something correctly, Murphy’s Law gets reinforced big time.  Granted there are degrees of correctness, but blatant disregard for tried and true power wiring is not recommended. 
Things that you can get away with on the bench for short term testing seldom work out when put in service 24/7 unattended especially when it is your source of income.
You can’t afford pissed off customers, nobody wants a service that’s unreliable (even if it is cheaper than other options).

I agree.   But is there really anything wrong with modifying this PDU if they won't accept the return, and then buying the same, modifying that for redundancy, instead of buying something like 6 of the P9S13A's?   When I did a quick price check, the price of those P9S13As where more than the P9S16As.

Once this guy leaves, I'll go through the numbers again, figure out exactly what our load is, what will need to be ran off the PDUs, what won't.   For my workbench, I wanted to purchase a switched and metered PDU (doesn't have to be HPE) that was around 10-foot tall, but I can't seem to find one.   A general power strip I can find.   Right now, that's what I have, just a general power strip.

[james_s]

Look on ebay for PDUs, there are tons of perfectly good used ones that are cheap compared to new. It's not like they're something that tends to wear out.

[IanB]

But what I was saying was could HPE make a PDU for 240V North America that provides a higher load using something like double-pole 40-amp breakers?

It seems that they could, but they don't. For higher loads they seem to prefer three phase supplies, probably because that is what will be found in data centers. If they made a high power 240 V single phase PDU for North America they would have no sales because no customers would have a need for it.

Your existing P9S16A PDU is designed to handle 32 A and is fitted with two 16 A single pole breakers. If you were to replace the single pole breakers with double pole breakers rated for 16 A continuous, and if you were to plug the PDU into a 40 A 240 V circuit (using 8-gauge wire for the circuit and using plugs rated for 32 A continuous) then I suppose, theoretically, it would work.

But since you would be going off script, you would have to absorb the risk of things going wrong and would void any warranty support.

[Gregg]

Now that many of us on this forum have spent countless hours advising Spork about powering his secret project, I would like to make a guess as to what this project might be.

My guess: Spork is turning his basement into a node for a VPN.  If so, his revenue will depend on up time and throughput but the IT administrators want control of things like powering down servers and routing data.  But a power outage won’t be the end of this business model because the customers can be automatically connected via another node.  The VPN saves a ton of money by not needing to be located in expensive data centers plus they have a continuous tech on site.  It could be a nice steady source of income that may grow.  Worst case the VPN goes out of business leaving Spork with a sizeable investment not yet amortized. 

[Spork Schivago]

Now that many of us on this forum have spent countless hours advising Spork about powering his secret project, I would like to make a guess as to what this project might be.

My guess: Spork is turning his basement into a node for a VPN.  If so, his revenue will depend on up time and throughput but the IT administrators want control of things like powering down servers and routing data.  But a power outage won’t be the end of this business model because the customers can be automatically connected via another node.  The VPN saves a ton of money by not needing to be located in expensive data centers plus they have a continuous tech on site.  It could be a nice steady source of income that may grow.  Worst case the VPN goes out of business leaving Spork with a sizeable investment not yet amortized.

I wish I could say yes or no.   I have a gentleman working with me now, and he's good, but he doesn't even know the grand scheme, just the stuff he needs to work.

Originally, I designed something, years ago, and I believed in open hardware / open software.   I thought that by releasing our invention open hardware / open software, people would come together and work on it as a team, much like they did with the original open-source PS3 Toolchain.   I developed the circuit board, released under a GPL license, he programmed the microcontroller.

Then the next thing I know, he's selling a slightly modified version on his site.   Turns out we had different ideas of what the purpose of the open hardware / open software was.   Unfortunately, under the license I had used, he was fully within the rights to legally do what he did.   However, his run has ended and he made a little bit of money I'm guessing, but that was it.   He couldn't improve the design any, because he didn't really know it.

I've spent a lot of years learning more, a lot more.   Reading various books on circuit design, saving up money to purchase expensive software, talking to various companies who are interested in selling what we're working on, etc.

Anyway, I wanted to apologize for my absence.   It seems there's something more wrong with me then just stress.   Yesterday, my wife came home from work at 0945 to meet her mother and give her a gift for her sister.   She couldn't wake me up.   For some still unknown reason, she didn't call for help or anything and just left me and gave our daughter to her mother to watch.

I passed out the night before for a couple hours.   When I woke, I knew my sugar was off and thought I fixed it.   I slept over 15 hours the other night!!!!   When I finally woke up at around 1330, I realized something was really wrong.   I wanted to sleep SOOOOO bad, but saw coffee next to the bed and drank it.   It had enough sugar in it to get me out of bed and I measured my sugar level.   It was soooo low, the meter wouldn't recognize it.   I spent all day yesterday trying to stabilize.   I've had hypoglycemia for a while, but I've never had an issue (until recently) of my sugar going too high.   And usually, I was good just eating three squares a day, but now, that doesn't appear to be enough.

Lost a lot of weight real quick like (2 - 3 lbs a week).    Gotta pee all the time.   And what feels like my right kidney is freaking killing me!   So I go into the docs today at 1440 to get looked at, yet again.

[Gregg]

Spork,
You need to stop stressing out so much and reflect upon priorities in life.  Tell your wife and kids that you love them and thank them for their support; in other words try to turn the situation into the best possible scenario even if it isn’t fully what you want.  I sincerely wish you the best with your project.

[Spork Schivago]

Spork,
You need to stop stressing out so much and reflect upon priorities in life.  Tell your wife and kids that you love them and thank them for their support; in other words try to turn the situation into the best possible scenario even if it isn’t fully what you want.  I sincerely wish you the best with your project.

I think that advice could be applied to everyone and I think it's excellent advice.   Sometimes, as technicians, programmers, etc., we're working on the job and we're so close to finishing something, we want to just finish that last little bit.   Next thing we know, it's 0300 and the wife and child(ren) are in bed.

I always try to put my family first, my wife and daughter.   I have work to do, I always will.   Even if this business fails, there will still be work that needs to be done, but I set rules.   1) I don't work when I'm watching my daughter.   Sometimes, I'll cheat a little and send an e-mail or check the forums, but just real quick like.   When my wife gets home, I try not to work (unless it's something I consider very important) until her and my daughter take their daily nap together.   I make sure we have daddy / daughter time, daddy / mummy time, and daddy / daughter / mummy time.   I think the middle one is just as important, taking your wife out to dinner and grabbing a baby sitter or something.

Anyways, thanks for the advice Gregg.

[Spork Schivago]

As stated previously, here is the drawing I created to submit to the local code enforcement office.   He was nice and said he wasn't going to make me get a permit.   I still have to pay for inspection though and he gave me a list of numbers to call to find an inspector.   Once the rough wiring is done, I'll have them come up.   The code enforcer that I talked to is the one who will do the final inspection.

Glad I can start working now!

[IanB]

Nice diagram.

If you are buying new Romex for this installation rather than using existing stock you might try to obtain cable with black, red and ground cores rather than black, white and ground cores. This will avoid the need to use black electrical tape.

[Bratster]

I second the better Romex suggestion.

Get 10/3 w/gnd instead of 10/2 w/gnd.

Then you get you black and red for hot and a white for neutral. Even though you don't need the neutral now, it's not that much more money and is more flexible if needs change. Only $15-$20 difference in my area.

Sent from my Moto x4 using Tapatalk

[Spork Schivago]

Nice diagram.

If you are buying new Romex for this installation rather than using existing stock you might try to obtain cable with black, red and ground cores rather than black, white and ground cores. This will avoid the need to use black electrical tape.

Sorry for the late reply.   I've been almost dead for a few months now!  Docs think they know what's going on now, just gotta wait for a few more tests to come back.

Can I buy 10/2 with black and red instead of black and white?   I've seen 10/3 with black, red, and white....My wife already picked up the 10/2 (black, red, copper) I wanted the 10/3.   So we used heatshrink tubing for the white.   The inspector really loved that and felt that's how everyone should do that, so we earned some brownie points there!

[Spork Schivago]

I second the better Romex suggestion.

Get 10/3 w/gnd instead of 10/2 w/gnd.

Then you get you black and red for hot and a white for neutral. Even though you don't need the neutral now, it's not that much more money and is more flexible if needs change. Only $15-$20 difference in my area.

That's what I wanted, the 10/3 w/ ground.   I could have used all those wires, couldn't I?  Would it be wrong to have one of the neutrals going to ground the metal conduit box and the other ground wire going to the receptacle?   What I did, because I only had the 10/2 was run a pigtail off grounding screw on the receptacle, run a pigtail off the grounding screw on the box, and then twisted them together and used a wirenut to hold them together.

[6PTsocket]

Hello,

I have a device that has an IEC 60309 3-prong 32 amp plug.   It expects a 3-prong receptacle that has neutral, ground, and line.   Because I live in the US, how could I safely wire up the correct receptacle that has neutral, ground, and line, while still providing 240VAC and not violating the NEC?

I have single phase 120-0-120 coming into the house to the panel.

Thanks.

In the EU , from what I can gather, the 24O is between a hot and a neutral, plus a ground. In the US  the 240 is between two hots, with a neutral centered between them, plus a ground. Devices run on the potential difference between two points and don't care what their relationship is to the rest of the world. Connect the hot and neutral wires to the two hot terminals on an appropriately rated 240 volt plug and connect the ground wire  to the ground terminal. If you don't want to cut off your old plug you will need an IEC receptacle to make an adapter. Ground is ground everywhere so that is your safety. The only problem might be that your 50hz device does not like 60 hz. Transformers are to isolate or step voltages up or down. You already have the right voltage 120-0-120 is 240 volts between the 120 connections. Isolation serves no purpose here.

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[IanB]

Can I buy 10/2 with black and red instead of black and white?

I don't know, maybe not. You might not find it in a big box store, maybe you would have to get it from an electrical wholesaler. I haven't looked for it.

My wife already picked up the 10/2 (black, red, copper) I wanted the 10/3.

You mean black, white, copper?

So we used heatshrink tubing for the white.   The inspector really loved that and felt that's how everyone should do that, so we earned some brownie points there!

You put red heatshrink on the white wire? That's fine. You could also use a wrapping of red electrical tape.

That's what I wanted, the 10/3 w/ ground.   I could have used all those wires, couldn't I?  Would it be wrong to have one of the neutrals going to ground the metal conduit box and the other ground wire going to the receptacle?

Here I am confused. Neutral (white) is not ground (bare copper). The neutral wire has white insulation on it to indicate it is a live (current carrying) conductor, and must never be allowed to touch bare metal parts.

What I did, because I only had the 10/2 was run a pigtail off grounding screw on the receptacle, run a pigtail off the grounding screw on the box, and then twisted them together and used a wirenut to hold them together.

Again, confused. You had 10/2 cable with black (L1), white (marked red, used as L2), bare copper (no insulation, ground wire). The bare copper wire shall be connected to the ground screw on the receptacle, the box, and any other metal chassis parts. Pigtails may be used for this as necessary. Under no circumstances shall a bare copper (ground) wire be connected to a white (live) wire.

I do not understand why you say "because I only had the 10/2" ? Your 10/2 has a bare copper ground wire to connect to ground screws. Where was the problem?

[oPossum]

My wife already picked up the 10/2 (black, red, copper) I wanted the 10/3.

You mean black, white, copper?

black/red/bare is used for NEMA 6 and L6 series receptacles. They have L1, L2 and ground. No neutral.

[IanB]

black/red/bare is used for NEMA 6 and L6 series receptacles. They have L1, L2 and ground. No neutral.

Sure. But please look at the context:

Can I buy 10/2 with black and red instead of black and white?   I've seen 10/3 with black, red, and white....My wife already picked up the 10/2 (black, red, copper) I wanted the 10/3.

Given the context, do you now understand my question?

[oPossum]

I don't really understand any of your questions. I don't think he did anything wrong, and it passed inspection.

[IanB]

I don't really understand any of your questions. I don't think he did anything wrong, and it passed inspection.

Please. Spork asked, "Can I get cable with black, red and copper cores?" And in the very same sentence he said, "My wife bought some cable with black, red and copper cores."

Why ask that question if it is already answered?

So given the context of everything else, I think that was a typo. I think his wife bought cable with black, white and copper cores, and then when he installed it he put red shrink wrap over the white insulation to mark it as a live wire.

[6PTsocket]

You haven't been told you can't use NM-B to wire a fixed circuit from the breaker panel to a wall outlet. You can. That's why an electrician is able to do so and have the work pass inspection.

You keep getting hung up on "hot" and "neutral". But a circuit has two wires. You can think of them as "out" and "back". Whatever current flows "out" has to flow "back". 20 amps out, 20 amps back. The current in the two conductors is always equal and balanced. That's why you can't add up 20 and 20 to get 40.

You can work out for yourself why two 120 V, 20 A circuits do not add up to a 240 V, 40 A circuit. Think about it. 120 V x 20 A = 2400 W. Therefore 2 x 120 V x 20 A = 4800 W. But 240 V x 40 A = 9600 W. And 4800 W does not equal 9600 W. It doesn't add up.

If your load draws 30 amps then the "out" wire has to carry 30 amps and the "back" wire has to carry 30 amps, and each pole of the breaker has to carry 30 amps.

Two 120 v circuits do add up to 240 if they are coming from the two legs of a 240 feed and not the same leg. Either hot to neutral is 120. Hot to hot is 240.

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