Pool Light Tripping GFCI

[tcpiii]

Thanks, Poconos. A friend came over today who is much more adept at this things than myself. He read your note, and also contacted a friend of his who is an electrician. The electrician wrote this note:
"Based on when it shorts it means the wire it crimped at some place (could have happened when the wire was removed and put back in during the resurfacing of the pool) or is corroding in a spot, causing a higher amount of resistance in the line, which trips the breaker. So, the only way to fix it is to locate the crimped wire, and cut it out."
My friend checked the resistance, checked the wires that are not inside the tube going from the breaker box to the pool, dried out the fixture once again more thoroughly than I had done myself, and disconnected a second wire attached to that circuit (which was for an exterior light above the pool that has not worked since before we bought this house 8 years ago). Put everything back together . . . and the light stayed on for 20 minutes, longer than ever before this season, but still eventually tripped the GFCI.
I guess replacing the GFCI would be the next step, right?

[Watermom]

Jonboy --- If you are looking for your post, I started a new thread for you.

http://www.poolforum.com/pf2/showthr...-Tripping-GFCI

[Poconos]

A high resistance in a wire won't cause a GFCI to trip. Yes, a wire could be crimped and damaged but ANYTHING that causes leakage to ground should trip a GFCI. That could be bad or old insulation on a wire or dampness that has gotten into a crack in old insulation and other things. When your friend measured the resistance to ground what was the reading? Also got a question....120 volt lamp? If it's a low voltage lamp then there is a transformer in the system. Yes, next step is replace the GFCI.
Al

[tcpiii]

Al:
Thanks for your input. On Saturday we spent a while testing matters - and discovered a strange source of the problem. The bulb has a spot where the reflective material is absent. It so happened that that "hole" in the reflective coating caused light and thus heat to be aimed right at the grounding spring. By pulling out the light receptacle slightly, we are able to move the position of that hole enough so that the light no longer trips the GFCI. Clearly a temporary fix - I'll replace the bulb when I open the pool next spring. BTW, this is 120V, 500w lamp.

[Poconos]

I've been away for a few days. Crazy but at least you found it. Good detective work.
Al