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ThreePhaseEel has asked me a couple of questions. First, I want to thank him for the answer.

As to the color of the 3 phase wires from the pole, all are green. I don't see any white either. The high leg is the first wire from left in the box that is 208v. The second and third are 120v. So I think instead of A-B-C I have B-A-C. In the box the color of Bus bar C has been painted red but the voltage of this bar is 120. The voltages that you are showing are correct. What I don't understand, is where the white wire from the pole is. Although I see the white wire has entered the adjacent breaker box from the pole.

What should I do when I don’t see white neutral coming from pole to 3 phase panel?

Is it possible there is only one neutral for both single and 3 phase panels?

Can I use the neutral in single phase to connect to the single-phase 60-amp panel that is from 3 phase panel?

How can you distinguish #6 PE from XLPE?

What is this balancing issue warning that some people are talking about when you want to install a single phase sub-panel of a 3 phase panel?

Is it OK to have 60 amp breaker as feeder and as main sub-panel?

Which one will trip first if there is a short?

Finally a question about conduit. Can I use two 1.5” 90 degree elbows (like S shape) connected to each other?

  • Thanks Janessa, for your answer. The following is the clarification that you asked for: – mike007 May 31 '15 at 19:41
  • I have a Delta 3 phase load center box w/o main breaker and over head powered by 3 #6 overhead wires with no load going out. legs to ground are 208, 120 and 120. All hot to hot are 240. White wire goes to the adjacent separate service single 120/240 box. I want to install a single phase 60A 120/240 sub-panel by using AL#4 SER wire to connect this wire to two 120v connectors of an existing 60 amp breaker in this box. My question regarding the tripping of the breakers was about this breaker and the one on the sub-panel. Space used to be a carpenter shop but it is now a two residential unit. – mike007 May 31 '15 at 20:49
  • So I have 2 separate service boxes (single phase 120/24 and 3 phase) next to each other powered by overhead wire going to them. The neutral only goes to the single phase box. The 3 phase is power by 3#6(green) and a ground wire. The box is a load center without main breaker. There is a 60A 3phase breaker that I am going to us to power the sub panel wit an AL#4 SER service entrance wire. – mike007 May 31 '15 at 21:02
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Alright your question is all over the place. Let me try to figure this out. You have a three phase panel. The different legs are all 120V when measured to ground. But if you measure between any leg to another leg you have 208V. In that panel you have no neutral wire. Just three hots and a ground? You cannot just say that the voltage was 120V on the bus bar without saying what you measured it to (to another leg or ground or what?)

Are you sure this is a three phase panel. The 208V measured from Hot to Hot indicates that it is but do you know how to tell? 3 phase is usually only found in commercial and industrial sites. Not in houses.

What is this box that the white wire goes into thats adjacent to the pole? Does the power go from the outside overhead lines, to a meter base (where power is measured and reported to power authority?) and than to your three phase panel?

Are you now trying to make your own 60A single phase sub panel from your three phase panel? I am still not sure if you understand how 3 phase works/is. We can help you but you need to be more clear.

I am not sure what PE wire is and I am not sure if you are talking about the main service conductors here when you are wondering. But XLPE has a clear almost like shrink tubing around it. If you were to scratch the outside of the individual cable it would sort of rip the outside. Kind of like it had scotch tape on the outside and you scratched it ripping some up. It should also say in writing on the cable XLPE if you can see any writing.

Balancing your panel just means putting the same amount of power on each phase if you can. So if you had 3 big assed air compressors, you would try to put one compressor on Phase A, one compressor on Phase B and one compressor on Phase C. (Or on Phase A+B, Phase B+C and Phase C+A if they are 208V). Do you see. So you just try to evenly space your big loads if you can. The smaller loads you don't need to worry about as much. But if you were doing a sub panel you would put the sub panel on a leg that doesn't have very many big loads on it in the main panel.

If you have two 60 breakers than on a short would trip the breaker that responds the best. Thats anybodies guess. Is your main panel a 60 A breaker and you would like your sub panel to be 60A? Or is the load your adding 60A and the main breaker is only 60A?

Yes you can use 2, 90 degree elbows together. Depending on your cable size it could be hard to pull through if you did them back to back. If you could put a short strait section between them it would be better. Would 2, 45 degree angles work in this application. Its not as harsh on the corners to pull through. Unless your cable is small compared to the pipe and than it shouldn't matter to much either way.

So you are missing tons of information. Let us know.

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