Sounds like you have leakage current flowing past the breaker. An easy
way to be sure is to turn the breaker off and check the voltage. Then
plug a lamp into one of the sockets on that circuit and turn the lamp
on. It should not come on. Now check the voltage across the switch again
and I suspect it will be zero.
Go ahead and replace the switch, then turn the breaker back on and
everything should be fine.
The reason you are seeing voltage on the switch is that the circuit is
open with the switch off. Any leakage current will produce a voltage
into an high resistance (open circuit). I wouldn't worry about it unless
there is still voltage (more than a volt or two)across the switch with
the lamp plugged in. If you have voltage, replace the breaker.
Thusly spake Bob Spidell:
> Got a question for the electrician-types out there:
> I needed to replace a wall switch, and when I finally determined which
> was on the circuit when I opened the breaker I still saw 40V AC on the
> two poles.
> Does this mean I have a ground loop, or is there something about house
> I don't understand. The house is old--built in the late '50s--if that
> matters, and I think
> it's mostly two-wire circuits.
Pat Horne, Owner, Horne Systems
(512) 797-7501 Voice 5026 FM 2001
Pat@HorneSystemsTx.com Lockhart, TX 78644-4443
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