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| How to wire up a 240VAC receptacle |
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| IanB:
--- Quote from: Spork Schivago on May 19, 2018, 07:20:11 am ---I could technically power a circuit where the supply is 24V and the return is 12V. --- End quote --- No, in a two wire system it is not possible "to have one wire at 24 V and the other at 12 V". Voltage is defined as the difference in potential between two wires. No single wire can ever have a voltage on it in isolation. Every time you talk about a voltage you have to talk about the voltage between this wire and that wire. So all you can say about two wires is that "they have a voltage of 12 V". All you can say about a single wire is "we don't know anything about voltages because there is only one wire". (Sometimes the other "wire" can be ground, or a water pipe, or something, but this is still a "wire" from an electrical and safety perspective.) --- Quote from: Spork Schivago on May 19, 2018, 07:20:11 am ---With the 120-0-120, I understand how it works now. I also understand why if I were to not use a double pole breaker but tried wiring up a NEMA L6-30R using a 30-amp single pole breaker in slot 1 and slot 2 (opposites sides of the panel), it wouldn't work. I'd have 120VAC, not 240VAC. --- End quote --- No, you don't seem to understand. You would have 240 V AC, which is exactly what the computer power supplies want. The reason you can't hook up your existing PDU to the L6-30R receptacle is one of safety. It doesn't comply with North American electrical standards. It was designed for another system, outside North America. |
| Spork Schivago:
--- Quote from: IanB on May 19, 2018, 07:03:37 am --- --- Quote from: Spork Schivago on May 19, 2018, 06:37:43 am ---With the European 240VAC, don't they generally have 240VAC going down L1 and Neutral to Neutral, Ground to Ground (where Neutral would be connected to Ground, like in my breaker panel)? If so, wouldn't they receive a short if they tried hooking my BGA rework station (which is wired with L1 = 120VAC, L2 = 120VAC, N = Neutral, E = Earth) directly into their outlets, just by changing the NEMA L6-30P I wired to the end of it? --- End quote --- You have listed four wires (L1, L2, N, E), but in the L6-30P there are only supposed to be three wires (L1, L2, E). There is no neutral. Your BGA rework station is only supposed to have three wires too. In the European outlet there are two wires carrying 240 V between them, and a third wire for safety ground. In the USA the L6-30 receptacle has two wires carrying 240 V between them and a third wire for safety ground. So the situation is really the same in Europe as it is here from an electrical perspective. It is only the safety arrangements that differ. We call a wire "hot" or "live" because it is effectively hot and will hurt you if you touch it. We call a wire neutral because--theoretically--it won't hurt you if you touch it (but don't rely on this). There is no difference between live and neutral as far as carrying electric current is concerned, there is only a difference with regard to safety and protection arrangements. --- End quote --- I'm sorry, I haven't gotten a lot of sleep lately, but yes, you are correct. The NEMA L6-30P / L6-30R only has 3 wires, not four. So in Europe and other parts of the world that use 240VAC, it's just like ours, where 120V goes down one wire, 120V goes down another? This is what my European friend was talking about I think when he said it was a language barrier and that Neutral was meant to be hot. If that's the case though, and they have two wires carrying the 240V load, then my PDU wouldn't work over there either, would it? Because we still have single pole breakers. They'd need 1-phase 240VAC, not two-phase. This guy I know had me come to his house to fix his electricity. He's really intelligent, but should not be messing with this stuff, and I stressed that many times, but he said if his house burned up with him in it, he'd be happy. Anyway, he had a furnace in his basement and lives downstairs. He wired up some sort of forced air, which was just pure genuis, but he wired the receptacle incorrectly and it didn't trip a breaker, but sparked. Then none of the loads on the circuit worked. So I went through and probed them with my multimeter and I have a small device I plug in to show me if they're wired correctly, and a no-contact voltage detector. I'm working my way backwards, right? I get to this receptacle, plug my device in, nothing, but the no-contact voltage detector says there's juice. I put my DMM on there, 14VAC. I'm like what the heck? I know it was dumb, but I had to check. I touch the receptacle, and sure enough, a bit of a tingle. I go down stairs, trace the wire, and come to a junction box. This is where it gets real bad. He tied into 12-gauge wire using 14-gauge wire and ran it to the new receptacle he installed for his forced air hookup. Every outlet in the house had no ground wire hooked up, and this is why it never tripped the breaker. In the actual junction box, the wirenut had actually partiatially exploded. Some of it was melted. I told him this is why you need to not be doing this. I can show you how to do it safely, but you cannot have this type of setup, you're going to get hurt or killed. That's when he said he didn't care, so I didn't know what to do. I fixed it, but said he shouldn't be using the 14-gauge. It's a danger. He needs to switch it out with 12-gauge. I tried telling him, how would you feel if you was at work and your house burned down and your dogs couldn't get out? I dunno if he ever switched it out or not. He got real paranoid after that and started talking about cameras in the tree's and the FBI watching him or something so I left. |
| Spork Schivago:
--- Quote from: IanB on May 19, 2018, 07:30:57 am --- --- Quote from: Spork Schivago on May 19, 2018, 07:20:11 am ---I could technically power a circuit where the supply is 24V and the return is 12V. --- End quote --- No, in a two wire system it is not possible "to have one wire at 24 V and the other at 12 V". Voltage is defined as the difference in potential between two wires. No single wire can ever have a voltage on it in isolation. Every time you talk about a voltage you have to talk about the voltage between this wire and that wire. So all you can say about two wires is that "they have a voltage of 12 V". All you can say about a single wire is "we don't know anything about voltages because there is only one wire". (Sometimes the other "wire" can be ground, or a water pipe, or something, but this is still a "wire" from an electrical and safety perspective.) --- Quote from: Spork Schivago on May 19, 2018, 07:20:11 am ---With the 120-0-120, I understand how it works now. I also understand why if I were to not use a double pole breaker but tried wiring up a NEMA L6-30R using a 30-amp single pole breaker in slot 1 and slot 2 (opposites sides of the panel), it wouldn't work. I'd have 120VAC, not 240VAC. --- End quote --- No, you don't seem to understand. You would have 240 V AC, which is exactly what the computer power supplies want. The reason you can't hook up your existing PDU to the L6-30R receptacle is one of safety. It doesn't comply with North American electrical standards. It was designed for another system, outside North America. --- End quote --- No, I do understand. slot 1 and slot 2 are on the same phase, from the panels perspective. Take two computer PSUs. Strip the 12V wire from each of them. Tie them together. Plug both into the same outlet. Measure the voltage in reference to ground. What do you get? 24VDC? No. 12VDC. Now, do the same, but plug one of the PSUs into a circuit powered by the other mains coming into the house. What do you get? Should be 24VDC, not 12VDC. I'm tired, I did a horrible job, I was trying to give a simple analogy of something we call differential signaling, but after I get some sleep, I'll come back and update it proper like. I have been awake for over 36 hours now. I gotta go to bed, but I love talking to you guys and learning this stuff. So hard to walk away. |
| IanB:
--- Quote from: Spork Schivago on May 18, 2018, 09:19:20 pm ---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? --- End quote --- I would send the PDU back and order the other two PDUs. The reason being that that other PDUs are designed and specified for installation in North America and they comply with the electrical and safety requirements of the North American electrical code. Your existing PDU is not code compliant and is not suitable for connection to a North American electrical supply. It is intended for another market elsewhere in the world. This is why it has a strange plug on it and why electricans don't want to touch it. You could, theoretically, install the transformer and the sub-panel, but it's going to be really complicated getting it to pass inspection because it will be a strange and abnormal setup. If you don't want to take the responsibility of ordering the other PDUs just on the advice of this forum, you should find someone in your line of business to consult who can offer appropriate expert advice. I do not think you have been well advised by the HPE sales consultants in your journey so far. |
| IanB:
--- Quote from: Spork Schivago on May 19, 2018, 07:39:55 am ---slot 1 and slot 2 are on the same phase, from the panels perspective --- End quote --- No, slot 1 and slot 2 are on the opposite phase, from the panel's perspective. That is why slot 1 and slot 2 have 240 V between them. |
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