Odd electrical issue

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C

Cajun

0
Dec 16, 2011
124
Prosper, Texas
I'm having an interesting electrical problem and would like some guidance on where to look next.

I have a gfci that is tied to several things.
- pool light
- spa light
- grill outlet
- other outdoor plugs installed by pool company

Items I added to this same circuit.
- outdoor led lights
- stenner pump

At first all was fine then the GFCI started tripping when I turn on the pool and spa light (these are on separate switches). I can tun on just the pool or just the spa light and all is fine but if both are on it trips. other items seem to not matter one way or the other.

I have tried replacing the GFCI with another one and all worked for a little while, few months, (I could turn on both the pool and spa lights at the same time). Now the problem has returned. Any thoughts on where to go next?

TIA
 
It's at least a 15 amp GFCI. The pool light is 500 watts and the spa is 100 watts. I can have everything else turned off and turning on just those 2 cause the gfci to trip. That should be under 5 amps so i dont think its an overloaded circuit causing this issue.
 
Your pool lights are supposed to be on their own circuits by code. My bet is you have a poor connection in the neutral someplace in the circuit, and pool junction boxes would be the first place I'd look
 
I had the same problem with my 4 pool lights. They are switched separately (pool, wading pool, spa, fountain) and when they were all on the GFCI tripped. I replaced the GFCI but that didn’t help. Next I measured the resistance of each light’s leakage to ground and found the problems.

It turns out that eventually the light’s insulated cord will start to degrade and allow some water in causing the GFCI to trip. The lights use special submersion grade double insulated wire but it is continually submerged and will eventually fail. In my case this was at about 10 years. The GFCI will trip at 4 to 6 mA leakage or about 18K ohms between the line/load and ground for a 110V circuit. Here is a great discussion on how they work:
http://www.nema.org/Products/Documents/NEMA-GFCI-2012-Field-Representative-Presentation.pdf

I had one light with measurable leakage resistance to ground and a second light that had water in the conduit between the controller relay box and the elevated light J-box causing leakage with the feed wiring. My fix then was to replace the one bad light and then the feed wiring to the other light circuit after I got all the water out. My pool is now 23 years old and I just had to replace another 4” light with the same symptoms.

If you have a multimeter and are familiar with working on your wiring you can check this yourself. If not, get a qualified electrician because you can injure or kill yourself. Here is what I would do:

  • Turn off the breaker that feeds the pool’s subpanel.
  • If your lights are on mechanical switches turn them all on.
  • At the GFCI measure the resistance between the line & ground and the neutral & ground. Ideally this will be an open circuit but if it’s less than 100K you have issues and at 18K it will trip. Isolate and check each light separately to find the defect(s).
  • If your lights are on relays you can check the resistance at the elevated J-box for each light.
 
Thanks CA92807 for the writeup and thanks to everyone else for your help.

My switches are controlled via software but I'll measure from the point where they are tied into the panel to determine what light or fixture has the issue. I suspect I will find both have a some leakage and the total leakage when both are on is enough to trip the gfci.

Thanks again.
 
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