Electronics > Beginners

How to wire up a 240VAC receptacle

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Spork Schivago:

--- Quote from: Bratster on May 19, 2018, 08:11:43 pm ---
--- Quote from: Spork Schivago on May 19, 2018, 08:06:59 pm ---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?

--- End quote ---
1400w/240v

So just under 6 amps.

Sent from my Moto x4 using Tapatalk

--- End quote ---

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:

--- Quote from: Monkeh on May 19, 2018, 08:15:22 pm ---
--- Quote from: Spork Schivago on May 19, 2018, 08:06:59 pm ---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?

--- End quote ---

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.


--- Quote from: Spork Schivago on May 19, 2018, 08:08:18 pm ---We will be drawing more than 5.7 kW from the server, therefore, we need at least 2 PDUs.

--- End quote ---

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.

--- End quote ---

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:

--- Quote from: Spork Schivago on May 19, 2018, 08:35:57 pm ---Even though L1 and L2 are each 120VAC in reference to ground?    Just wanted to make sure.
--- End quote ---

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:

--- Quote from: Bratster on May 19, 2018, 08:37:43 pm ---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

--- End quote ---

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.

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