Pool lights GFCI tripping head-scratcher

[Glenn228]

A confounding situation.

Setup: Two pool lights (500W), one Spa light, Jandy controller with wired remote in house. Pool lights on their own relay, spa on another.

Problem: Pool lights will trip the GFCI almost always. Spa light works. When we can get the pool lights on, turning spa light on will trip GFCI always.

Detail: We recently had one of the two pool lights replaced after it being out for awhile (full fixture replacement). He also replaced the lens and gasket on the other light, which was working before.

Pool installer couldn’t get lights to not trip GFCI, told us it needed replacing. Had electrician come out, replaced GFCI, no change in results.

The pool lights will immediately trip the GFCI, but if you keep resetting and trying, they will go on. Then, they (at least sometimes) can be turned on and off in succession without tripping. Any time you add the spa light it trips - no way to get the three to work.

Electrician spent nearly two hours with me. We tried each light by itself, on other relays in the Jandy. All lights work independently. One pool light and the spa light will work.

The new pool light goes to one junction box where the spa light also goes. The second pool light (the one whose fixture wasn’t replaced) goes to the main circuit panel where the breakers are. Electrician confirmed the first pool light and spa light shared neutral.

It seems I can get the two pool lights to work by cycling the tripping and reset 3-5 times. Then it will work and stay on indefinitely. It will turn on and off if you do it shortly after getting the lights on. If you wait awhile and turn off an on, it will trip. Almost like it’s a heat issue (I’m not an electrician) - where the GFCI tripping allows it to accept the circuit when it’s been used/hotter.

When trying to get all three lights on, adding the spa light when the pool lights are on (when we can get them working) the GFCI trips about one second after hitting the spa light switch. When done in reverse (spa light on, add pool lights) it immediately trips.

I think I’ve covered all the permutations. The electrician left in the evening scratching his head.

Any thoughts or ideas? Thank you.

 

[JasonLion]

Welcome to TFP!

That sounds much like a very small leak in the insulation somewhere, allowing just enough water infiltration to cause extremely low current shorts to ground. If the fault is small enough to be right on the edge of tripping/not tripping the GFCI, it could easily have complex patterns of behavior as you describe.

 

[danpik]

Ask the electrician to megger the lines to the lights

 

[stebs]

Are they all on separate breakers and gfci's? The way I'm reading it is you have an issue with the neutrals

 

[Glenn228]

Thanks for the quick replies.

All lights are on the same breaker (I believe) and use the same GFCI (which has been replaced with no change in results).

I'll bring up the Megger Test to the electrician, thanks danpik.

Thanks,

Glenn

 

[TomBorg]

He also replaced the lens and gasket on the other light, which was working before.

I would double-check that this was done correctly. Perhaps the gasket got a kink or a wrinkle in it, and leaked. But even this probably wouldn't trip the gfci, unless you have a salt-water pool. Perhaps the old light's cable has old, brittle insulation, and the flexing of the wire when it was pulled from and put back into the niche created a crack in the insulation.

I assume the electrician tried disconnecting each light at the junction box to try to narrow the problem down? (If not, time for a new electrician. )

 

[jonathankass]

Hi - did you figure out what the problem was?

I have a somewhat similar challenge - pool and spa lights are on a GFCI. I can turn either light on, and leave on for hours, and have no issue. If I turn both on at the same time, GFCI pops. I will be going through the junction box wiring, I've already replaced the gasket and bulb in the spa, but I'm stumped as to why only the combination pops the GFCI, while neither will pop it on their own. So curious if you solved this.

Thanks

Jonathan

 

[danpik]

Could be bad insulation in the wiring. one light won't draw as much current as two. Two lights may draw enough current that a weak spot in the insulation may allow some leakage to ground which will trip the GFCI.

 

[marcgr]

Could be a shared neutral somewhere. Each live must go back to it's own neutral and to no other neutral. If you have neutrals from different circuits joined together at some point (other than at the breaker box), weird stuff happens.

Do you have AFCI on that GFCI? I have heard some of the newer AFCI+GFCI breakers have sensitivity to how much wire is connected to them (unlike the older GFCI-only, which didn't).

Hope that helps or gives you a point to look at,

Marc

 

[jonathankass]

Thanks - will keep an eye out for anything I can see that looks like its thin / fraying.

Could be bad insulation in the wiring. one light won't draw as much current as two. Two lights may draw enough current that a weak spot in the insulation may allow some leakage to ground which will trip the GFCI.

 

[jonathankass]

Thanks - just double checking - the GFCI is an outlet, not a breaker. Breaker isn't popping just to be clear, just the GFCI. No AFCI as far as I can tell. I don't think there is any combination of neutrals happening prior to getting back to the GFCI (or breaker), but of course there are alot of neutral and load lines being tied in the junction box where the underground conduit lines (2 for the pool lights, and 1 bringing the switch signals from the house) connect with the pool control panel. Haven't found any obvious suspects yet, starting to think I have to get another GFCI outlet just to make sure this one isn't too sensitive. That and pull the pool light I guess just to make sure it isn't actually leaking though I think that would trip the gfci without the spa light being turned on...

Thanks again