How to wire up a 240VAC receptacle

[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

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[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.



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[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.

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[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.