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| How to wire up a 240VAC receptacle |
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| 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! |
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