DerbyDad03 wrote:

On Jul 7, 1:43 pm, "M PRESSMAN" wrote:

I just replaced a 3-way switch, and when I was testing, I noticed that there
was 30 volts (Radio Shack analog meter) at the light socket when the
switches were off. I tried using one of the little idiot lights that glow
with voltage, and indeed, it glowed weakly. The light and the 2 3-way
switches work perfectly though. This circuit is fed by old knob and tube
wiring. Should I worry that something nasty is going on?

Thanks,
Michael


You could have a shared neutral. I have one in my house and I have to
turn off the breakers for both circuits to avoid a situation like you
describe. The breakers should in fact be ganged. (It's on my list!)

See this site: http://www.thecircuitdetective.com/twocircuit.htm


C'mon, 30 VOLTS due to a shared neutral?

That would take more than just a "shared" neutral, it'd take a very
poorly connected or high resistance neutral, in which case it's unlikely
that as the OP said, the light and the switches work perfectly.

More likely slight resistive or capacitive leakage currents tweaking the
test meter, as several others have said already.

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.98*10^14 fathoms per fortnight.