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| How to wire up a 240VAC receptacle |
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| Spork Schivago:
--- Quote from: Monkeh on May 16, 2018, 12:15:48 am --- --- Quote from: Spork Schivago on May 16, 2018, 12:14:03 am ---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? --- End quote --- 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. --- Quote ---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. --- End quote --- I can't speak to your codes. As for IP ratings, don't put it outside and you won't need IP67... --- End quote --- 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:
--- Quote from: Spork Schivago on May 16, 2018, 12:18:37 am ---Do you mean one of the hot legs won't be protected by the upstream breaker? --- End quote --- It will be protected only by the upstream breaker. |
| Richard Crowley:
--- Quote from: Spork Schivago on May 16, 2018, 12:14:03 am ---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? --- End quote --- 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. --- Quote ---That device Richard Crowley linked too, I call that a step-up transformer, I'm not sure what they call it, --- End quote --- 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. --- Quote ---but that would safely complete the requirements to provide the necessary 240VAC single-phase that I need, correct? --- End quote --- 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. --- Quote ---Where I wouldn't be violating any codes, etc? --- End quote --- 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. --- Quote ---I want to find something with at least IP44 rating, but maybe IP67. I dunno yet. --- End quote --- 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:
--- Quote from: Richard Crowley on May 16, 2018, 12:32:25 am --- --- Quote from: Spork Schivago on May 16, 2018, 12:14:03 am ---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? --- End quote --- 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. --- End quote --- 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. --- Quote from: Richard Crowley on May 16, 2018, 12:32:25 am --- --- Quote ---That device Richard Crowley linked too, I call that a step-up transformer, I'm not sure what they call it, --- End quote --- 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. --- End quote --- Thank you for the clarification there! I didn't thoroughly enough. I understand. --- Quote from: Richard Crowley on May 16, 2018, 12:32:25 am --- --- Quote ---but that would safely complete the requirements to provide the necessary 240VAC single-phase that I need, correct? --- End quote --- 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. --- End quote --- I would rather try wiring it up myself, properly. Are you familiar with the brand name at all? Are they any good? --- Quote from: Richard Crowley on May 16, 2018, 12:32:25 am --- --- Quote ---Where I wouldn't be violating any codes, etc? --- End quote --- 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. --- End quote --- 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. --- Quote from: Richard Crowley on May 16, 2018, 12:32:25 am --- --- Quote ---I want to find something with at least IP44 rating, but maybe IP67. I dunno yet. --- End quote --- 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? --- End quote --- 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. |
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