Alexander Galkin wrote:

I wired my finished basement myself. In general everything was fine, I had
it inspected before insulating walls and ceiling and putting drywall. I have
been using power in basement for over the year and nothing was wrong.
However, on final inspection the electrical inspector and I found a very
weird problem that I need now to correct. I have the following wiring
diagram in basement:

- dedicated 20 A circuit to basement lighting, total 26 recessed lights 65 W
and 50 W
- dedicated 20 A circuit for basement rooms receptacles
- dedicated 20 A circuit for sump pump
- dedicated 20 A circuit for washer / gas dryer
- dedicated 20 A circuit sewer ejector pump
- dedicated 20 A circuit for basement bath
- dedicated 20 A circuit for garage receptacles
- 50 A basement workshop sub-panel powering 5 dedicated 115 V / 20 A, 2 220
V / 20 A shop receptacles circuits, and 1 15 A shop lights circuit

When I switched off basement room receptacles circuit breaker while all
others except sub-panel which does not seem to affect the problem were on we
found there is 8 V power in that circuit. Switching off some of other
circuits reducing this voltage to about 2 V and only switching off all new
circuits brings disconnected voltage to zero as it should be.

Can anyone give me a clue what cane be a source of this weird residual
voltage in disconnected circuit?



Are a bunch of your wires running for long lengths in parallel through
the same holes in the studs? It is a long shot, but it might be
inductive coupling. Were the circuits that had the breakers still on
loaded? That is, were lights or other things on such that the circuits
had current flowing in them?

Typically, if Romex-style cable is used the return current in the white
wire should cancel the field from the black wire and thus there
shouldn't be any significant net field to affect adjacent wires,
however, sometimes strange things can happen.


Matt