My colleague has a revised version of the reading:

L1-L2: 382
L1-L3: 212
L2-L3: 222

L1-N: 216
L2-N: 218
L3-N: 3

I don't know what has happened, but that certainly changed things right?

Sorry we didn't figure it out for you in time. But I'm glad you got it all sorted out (one way or another ) . But, yeah , it's definity two phase in the box, L3 is a neutral wire. It's call a split phase box, 1P to N at one outlet and 2P to N at the other outlet, so the box can run more amperage, but each outlet is single phase. The voltage difference, between L3 and N, is because, up the line, somewhere, power is going to neutral, so neutral is hot, and you're giving that power a second path to ground, when you measure the connection between L3 and N. Very similar to a series resistor.

Why everything is running at 220 volts , I can't say ? I guess you're in europe

 

Sorry we didn't figure it out for you in time. But I'm glad you got it all sorted out (one way or another ) . But, yeah , it's definity two phase in the box, L3 is a neutral wire. It's call a split phase box, 1P to N at one outlet and 2P to N at the other outlet, so the box can run more amperage, but each outlet is single phase. The voltage difference, between L3 and N, is because, up the line, somewhere, power is going to neutral, so neutral is hot, and you're giving that power a second path to ground, when you measure the connection between L3 and N. Very similar to a series resistor.

Why everything is running at 220 volts , I can't say ? I guess you're in europe

It doesn't really matter what I think now that they've got a working solution, but for the sake of any future readers, I disagree with your assessment.

As has been pointed out by others in this thread, the measured voltages line up quite neatly with Hong Kong three phase power, with 220 from each leg to neutral/ground and 380 between each leg. Also, the thread starter reported that the nearly-dead lines were all routed through breakers. Neutrals are not generally (never as far as I know) routed through breakers. So, I'm fairly confident that it really is meant to be the third phase of a three phase system and that there's some fault upstream of the breaker box.

 

It doesn't really matter what I think now that they've got a working solution, but for the sake of any future readers, I disagree with your assessment.

As has been pointed out by others in this thread, the measured voltages line up quite neatly with Hong Kong three phase power, with 220 from each leg to neutral/ground and 380 between each leg. Also, the thread starter reported that the nearly-dead lines were all routed through breakers. Neutrals are not generally (never as far as I know) routed through breakers. So, I'm fairly confident that it really is meant to be the third phase of a three phase system and that there's some fault upstream of the breaker box.

I don't understand how this refutes, my assessment, but sure OK Anyways, lookup "Arc fault breaker" , the neutral line runs through those. Without tracing the lines, who knows what anything is supposed to be ? I've seen all sorts of goofy stuff, where the only answer is "Who the hell wired this !?". Three phase with a 4 volt phase -- sure , why not ? I wouldn't be surprised by anything. That's just not what I think it is, I'd bet on a split phase box

 

It doesn't really matter what I think now that they've got a working solution, but for the sake of any future readers, I disagree with your assessment.

As has been pointed out by others in this thread, the measured voltages line up quite neatly with Hong Kong three phase power, with 220 from each leg to neutral/ground and 380 between each leg. Also, the thread starter reported that the nearly-dead lines were all routed through breakers. Neutrals are not generally (never as far as I know) routed through breakers. So, I'm fairly confident that it really is meant to be the third phase of a three phase system and that there's some fault upstream of the breaker box.

Hey if you want to reason it out me, I'm game.
How do you get a 220 volt line to, go to 4 volts ?

 

I don't understand how this refutes, my assessment, but sure OK Anyways, lookup "Arc fault breaker" , the neutral line runs through those. Without tracing the lines, who knows what anything is supposed to be ? I've seen all sorts of goofy stuff, where the only answer is "Who the hell wired this !?". Three phase with a 4 volt phase -- sure , why not ? I wouldn't be surprised by anything. That's just not what I think it is, I'd bet on a split phase box

When was the last time you saw a split phase supply where the voltage across the two legs didn't equal the sum of the two legs' voltages relative to ground?

220+220=380?

These voltages clearly match the output of a three phase transformer, not a split phase system. Most countries outside of the US don't even have split phase power at all.

Ultimately though, you're right that we can't know for sure. I could easily be wrong on this. I'm certainly no expert in international power distribution standards.

 

When was the last time you saw a split phase supply where the voltage across the two legs didn't equal the sum of the two legs' voltages relative to ground?

220+220=380?

These voltages clearly match the output of a three phase transformer, not a split phase system. Most countries outside of the US don't even have split phase power at all.

Ultimately though, you're right that we can't know for sure. I could easily be wrong on this. I'm certainly no expert in international power distribution standards.

We had a post collision.

Hey if you want to reason it out me, I'm game.
How do you get a 220 volt line to, go to 4 volts ?

Anyways , you pull two legs off a three phase, and run them to neutral, because you'er cheap, and also save on wire by recycling with the wrong color

 

Hey if you want to reason it out me, I'm game.
How do you get a 220 volt line to, go to 4 volts ?

Seriously, you've never seen an apparent stray voltage on a dead line? If the line is floating because of a blown fuse, tripped breaker, severed line, etc. then it can easily read as having some small voltage on it. I don't know if this voltage is induced through adjacent cables in long conduit runs, if it's capacitive coupling across the gap in the open circuit breaker, or some other mechanism I'm not thinking of, but I've seen it countless times. Turn a breaker off and then go measure the voltage at an outlet fed by that breaker. Quite often it won't read 0 volts. I feel like I see this more often on dedicated, high amperage circuits, but I couldn't swear to that. It definitely happened a lot on 240V 30A dedicated circuits for commercial coffee brewers when I was working on them. Many were hard wired in, so the only way to work on them was to kill the breaker. They'd read 4V or more pretty regularly. There was no "juice" behind it - if anything shorted that 4V to ground there was essentially no current flow, kind of like the leakage current in a lot of solid state switching devices (TRIACs, SCRs, etc.)

 

Seriously, you've never seen an apparent stray voltage on a dead line? If the line is floating because of a blown fuse, tripped breaker, severed line, etc. then it can easily read as having some small voltage on it. I don't know if this voltage is induced through adjacent cables in long conduit runs, if it's capacitive coupling across the gap in the open circuit breaker, or some other mechanism I'm not thinking of, but I've seen it countless times. Turn a breaker off and then go measure the voltage at an outlet fed by that breaker. Quite often it won't read 0 volts. I feel like I see this more often on dedicated, high amperage circuits, but I couldn't swear to that. It definitely happened a lot on 240V 30A dedicated circuits for commercial coffee brewers when I was working on them. Many were hard wired in, so the only way to work on them was to kill the breaker. They'd read 4V or more pretty regularly. There was no "juice" behind it - if anything shorted that 4V to ground there was essentially no current flow, kind of like the leakage current in a lot of solid state switching devices (TRIACs, SCRs, etc.)

Yeah but this just gets us back to tracing to line, Can't tell if it's a neutral with trans or a dead hot with trans.

But it does ask the question, why have a breaker and then up line somewhere, secret, hide a fuse ?

I'm going off the adage , "People will do that which is cheapest", here

 

Yeah but this just gets us back to tracing to line, Can't tell if it's a neutral with trans or a dead hot with trans.

But it does ask the question, why have a breaker and then up line somewhere, secret, hide a fuse ?

I don't know anything about fuses upstream, but I've seen sub-panels fed from bigger breakers in other panels plenty of times. Main panel has multiple >100A breakers each going out to feed sub-panels with smaller breakers for individual branch circuits. In that scenario, if the main panel had a defective breaker with one dead phase out of three, or if a wire had become disconnected, or if there were three individual breakers that should've been tied together, but one tripped, you could end up with a whole (sub-)panel that had a dead, floating third phase. In big buildings there's often a hierarchy of power distribution which ends up meaning multiple protection devices between the building power entrance and the final power consuming device.

 

I don't know anything about fuses upstream, but I've seen sub-panels fed from bigger breakers in other panels plenty of times. Main panel has multiple >100A breakers each going out to feed sub-panels with smaller breakers for individual branch circuits. In that scenario, if the main panel had a defective breaker with one dead phase out of three, or if a wire had become disconnected, or if there were three individual breakers that should've been tied together, but one tripped, you could end up with a whole (sub-)panel that had a dead, floating third phase. In big buildings there's often a hierarchy of power distribution which ends up meaning multiple protection devices between the building power entrance and the final power consuming device.

OK. So how did the OP "know" that was *the* breaker for that line, without finding the other sub-plane. He (assuming) must have, turned the breaker off, noticed there was no 4 volts , and then turned it back on again, with the other two phases still going ? How did he know he found the breaker for that line ?

 

OH, by the way black/yellow is ground on my kawasaki motorcycle, well, every kawasaki motorcycle, well, every kawasaki motorcycle that I have worked on

 

OK. So how did the OP "know" that was *the* breaker for that line, without finding the other sub-plane. He (assuming) must have, turned the breaker off, noticed there was no 4 volts , and then turned it back on again, with the other two phases still going ? How did he know he found the breaker for that line ?

Hmmm, not sure really. I mean, I'm obviously 100% in the realm of speculation here, and have been for a while. I enjoy playing devil's advocate and exploring possibilities, but I don't know. I'm not sure anything was identified as *the* breaker for anything. My reading of this situation was that the OP found ALL the breakers of one of the three phases in a sub-panel to be at the same low-voltage. I don't think that whatever controls them upstream has been clearly identified by anyone - it's all guesses over the internet. You guess it's a neutral, and I guess it's a third phase that's dead for any number of reasons upstream, but I don't think any of us "know" much about this particular situation!

 

OH, by the way black/yellow is ground on my kawasaki motorcycle, well, every kawasaki motorcycle, well, every kawasaki motorcycle that I have worked on

Yeah, the myriad number of wiring standards drive me crazy. Supposedly there are international standards that make things more consistent these days, but in practice I find there are still lots of bizarre exceptions. I mean, the US uses a green ground, while most of the world uses a green/yellow ground. That's not SO far off - you'd probably guess right most of the time going from one to the other... but then there's Japan: When I look online, every source I find says that they use green/yellow too, but every machine we ship there has to be wired with a special power cord that uses RED of all things for the ground wire, or they won't let it through the port into the country. It feels so wrong to use red for ground, but they won't accept anything else.

 

Hmmm, not sure really. I mean, I'm obviously 100% in the realm of speculation here, and have been for a while. I enjoy playing devil's advocate and exploring possibilities, but I don't know. I'm not sure anything was identified as *the* breaker for anything. My reading of this situation was that the OP found ALL the breakers of one of the three phases in a sub-panel to be at the same low-voltage. I don't think that whatever controls them upstream has been clearly identified by anyone - it's all guesses over the internet. You guess it's a neutral, and I guess it's a third phase that's dead for any number of reasons upstream, but I don't think any of us "know" much about this particular situation!

Yeah, know what you mean ! There is only so much good advice can ever do, I mean eventually someone has to go out and test something, we can't all be plato. But, I guess that will never help people trying to get tips, on how to really paint like an impressionist....... over the internet......in a chat forum ! And of course , we answer them , instead of telling them RTFM........ I, mean how else are we going to spend a saturday ?

 

Yeah, the myriad number of wiring standards drive me crazy. Supposedly there are international standards that make things more consistent these days, but in practice I find there are still lots of bizarre exceptions. I mean, the US uses a green ground, while most of the world uses a green/yellow ground. That's not SO far off - you'd probably guess right most of the time going from one to the other... but then there's Japan: When I look online, every source I find says that they use green/yellow too, but every machine we ship there has to be wired with a special power cord that uses RED of all things for the ground wire, or they won't let it through the port into the country. It feels so wrong to use red for ground, but they won't accept anything else.

WOW ....*facepalm*...red???......Well at least they keep the multi-tester guys in business ??

 

@Reloadron

While I have done quite a bit with three phase industrial power I have never seen an instance where a neutral line or ground line was fused or run through a breaker. Matter of fact I have never seen a neutral or ground switched.

Only one piece of equipment that was 90 A 3 phase 208 had a neutral breaker on the equipment. A Telemark e-beam power supply.