3 wire circuit

[caosesvida]

I am taking apart some old panels in a shcool. There are two? I guess three wire circuits in the conduits. They were all on single phase breakers. So I have to guess where they went. I am trying to get them attached ( electrically ) to the neutral that they are wired with. I was going to energize them and amprobe the neutral to see which one they are mated with. Any suggestions would be appreciated on whether or not they should be on 3 pole breakers, and the effects of not getting them all on three legs per neutral. If need be I can trace them all down ( more or less) but that would be very time consuming. Thanks for any reply's

 

[don_resqcapt19]

Re: 3 wire circuit

You need to know what the load is before we can tell you if common trip, common disconnect or single pole breakers can be used. If there are loads connected to the ungrounded conductors, you can identify the associated grounded conductor with an ohm meter. Disconnect all conductors at the panel, connect one lead of the meter to one ungrounded conductor, and the other to the ungrounded conductors one at a time. The ungrounded conductors that are connected to that neutral will show continuity.
You must not have two hots of the same phase connected to a common neutral as that will result in a neutral that is overloaded.
Don

[ July 09, 2004, 11:14 AM: Message edited by: don_resqcapt19 ]

 

[caosesvida]

Re: 3 wire circuit

the loads are lighting and receptacles, as far as I can tell. but you never know I've seen some of these runs go 1/2 mile to the other end of the building, you wonder why they went so far out of the way when other panels were closer.