While replaceing a lighting fixture, I found that one of my ground wires in an existing circuit has voltage. Everything has been functioning properly. How can this be?
Could you please describe how you measured the voltage? Across what wires and with what device and what was the reading?
There were 3 wires in the ground, and when I removed the wire nut, I noticed a small spark. I measured the voltage from the hot wire to the grounds, and it was 120V, but did not measure the voltage between the individual ground wires.
That would be normal to measure 120 volts between the hot and ground wire.
If you were measuring 120 volts between the neutral ( white) and the ground ( bare) then there would be a problem.
I resolved this myself.
The reason the ground wires were live was because I did not shut off the circuit breaker, only the light switch. That meant that other circuits on the breaker, connecting to the return grounds were still live.
Although there was no harm done, the lesson learned is: if there are more than 1 set of wires in a box, shut the breaker, or returns can have juice.
Bruce Job well done! I do want to point out that a Ground is green or bare wire. A return wire or neutral has a white or gray outer covering. When you were saying ground I was a bit confussed. An electrician always thinks green or bare wire when you say ground. A ground is never to have any voltage. Unless there is a fault or a mis-wired device. I am not being picky about the terminology. But, It could confuse someone trying to help you troubleshoot a problem. All is well you figured it out!!! Good Job:)
Raven you couldn't have said it any better. And good job Bruce. That part about a bare or green gound having voltage on it had me a little worried.