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| How to wire up a 240VAC receptacle |
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| Spork Schivago:
--- Quote from: IanB on May 14, 2018, 07:43:11 am ---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. --- End quote --- 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:
--- Quote from: Spork Schivago on May 14, 2018, 05:32:30 pm --- I'm going to be going to the ER later today and might not be back for a bit. --- End quote --- Our best wishes that they can diagnose the problem and solve it. --- Quote ---So, is there any danger with going for a larger breaker than what is actually needed? --- End quote --- 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:
--- Quote from: IanB on May 14, 2018, 04:33:05 am --- --- Quote from: Spork Schivago on May 14, 2018, 04:08:22 am ---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. --- End quote --- It will make a nice bang if you connect a hot wire to ground :o --- Quote ---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). --- End quote --- 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). --- End quote --- 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. --- Quote from: Spork Schivago on May 14, 2018, 05:32:30 pm ---I know I can run 14 gauge wire on a 20-amp breaker. --- End quote --- I'm not so sure about that. --- Quote ---I know I can't run 12 gauge wire on a 15-amp breaker. --- End quote --- 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:
--- Quote from: Paul Moir on May 14, 2018, 08:38:49 am ---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. ;) --- End quote --- 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 +. |
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