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Empty_Nest__Soo's avatar
Nov 22, 2014

Chasing electrical gremlins - GFCI outlet puzzle

On our trip at the end of last month, a table lamp quit working. Changing the bulb did not help, but a voltage detector showed voltage present at the base of the socket. I figured the switch in the lamp socket died.

I finally got around to buying a new lamp socket and I installed it today. No joy.

Using an outlet tester on the receptacle showed hot and ground reversed! I checked the breaker panel, and things were wired correctly on that end of the circuit. Some other outlets on that circuit checked out okay so I began to work upstream from the problem.

Long story short, I found the circuit routed through a GFCI outlet in the basement. That GFCI outlet and everything downstream tested “hot and ground reversed.” I pulled the line side of that outlet and found that the power coming in was correct, black = hot, white = neutral, bare = ground. The GFCI outlet was wired correctly, line side and load side. The problem has to be in the GFCI outlet.

After removing the GFCI outlet and connecting the appropriate wires with Scotch locks / wire nuts, everything downstream works okay.

The GFCI outlet does not seem to want to reset. I will replace it.

Also, I think I will re-route some wiring so that the interior outlets that are not near water, etc., are not routed through the GFCI receptacle, as I see no need for that kind of protection.

My question: I expected that if the GFCI outlet tripped, it would “interrupt” the circuit, i.e., break it. Could it have shunted the hot to ground, thereby activating the ground wires downstream, yet leaving the hot wire dead downstream?

I Googled to see how the GFCI outlets work, but came up empty.

Wayne
  • ScottG – In this case, it did reroute the power. At the downstream receptacle, a voltage detector showed ~120 volts between ground and neutral, with ground being hot. That is what puzzles me. I would never have expected the GFCI to have failed in that manner.

    The only problem with having the downstream outlets protected is that the ground wires became hot. And it took me quite a bit of time to discover that the voltage I was detecting was in the ground wire, not the hot (black) wire. I wish I understood why the GFCI outlet failed this way.

    Newman – In my case, I had no mis-wiring; the GFCI just did something I never would have expected.

    Brett – Having bought a 17-year-old coach, I expect little problems from time to time, and solving them will help keep the brain cells working. A $15 dollar part is not a big deal. I’m just hoping to learn something from the experience. :)

    Wayne
  • Wayne,

    Indeed, replace the offending GFI. They DO fail.

    Your wiring "around it" showed that the wiring was OK.
  • i just ran into this on a heartland bighorn it was the wiring in a junction had wrong size wirenuts and the hot was laying acrooss the ground. It was not pretty at the melted nuts and wiring
  • No it wont re-route the power - it probably just went bad.
    I would not change anything to negate it's effect to outlets down the line. It doesn't hurt anything to be protected.

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