Anyone have a good way to identify multi-wire circuits at the panel?
Have a case where the service and panel were replaced in a house with old wiring (knob and tube), and the original wiring was brought to a j-box (or boxes). New conductors were spliced on, with several circuits converted to shared neutral circuits, and new unlabelled conductors brought into the breaker panel. A similar instance where original wiring was done in pipe and again, no labelling of conductors on multi-wire circuits.
So in both cases, I can't tell by inspection if adjacent breakers are separate circuits or if they share a neutral (unlike a situation where the wiring is done with NM and you can see the three conductors of the Edison ckt entering the can together).
Going back to the j-boxes to find (and then buzz out from j-box to panel) the multiwire ckts would be my last choice. Tight crawl below the house, and a couple feet of blown in insulation in the attic, and who knows where those j-boxes are.
One approach I see as workable would be to turn on loads on all circuits, measure amperage on each ungrounded conductor at the breaker, and on each neutral. Flip off a breaker and see on which neutral there is a corresponding decrease in current. This should tell me which neutrals are shared, and by which circuits. This aproach will be somewhat tedious, as the Square-D Homeline panel is cramped and it'll be tight to get an amp-clamp onto many of the neutrals.
Man, I do like commercial work where the panels generally have a lot more room in which to work!
Anyone have another technique, or any ideas I could try?
Thanks,
Cliff
