On Wednesday, August 7, 2019 at 5:00:20 PM UTC-4, Ralph Mowery wrote:
In article ,
says...

I have a GFCI that keeps going bad. So this time I put a multimeter to the wires instead of using a voltage tester that just beeps. What I found is the hot (Black) wire from the circuit breaker panel has approximately 12 VAC on it, even when disconnected at both ends. I pulled the wire back and forth in the conduit to try to move
it if it was shorted to another wire, but that made no difference. There are 2 other hot wires running through the same conduit. when I shut either one of those off the voltage drops to about 4.5 and when I shut them both off it is zero. I assume this is inductance. Short of running the wire in a separate conduit can I fix this and
is it what is causing my GFCI's to fail.



Most anytime you have wires next to each other there will be a small
voltage in the wire not connected. Many digital meters will show some
voltage, but this is what most call induced voltage. Either by
capacitance or inductive coupling. Nothing wrong with the wiring.

That voltage is nothing, you should see it in a plant that has a dozen
or more hot wires and in 200 or more feet of conduit. I have seen
nearly 120 volts in it, the same as the wires with power on them.
Enough current to give a good shock to you.

I doubt that voltage would cause the GFCI to fail. You should probably
look for another cause.

+1

What is the failure mode of these Gfcis? If there was some unusual surge that hits them, then I could see that damaging the electronics.