GFCI outlet for pool lights keeps tripping

[pcm2a]

My voltmeter has a clamp on it, maybe to measure current. However, it's an auto meter so there are no settings. Meaning no controls to select anything.

I measured the hot side of each light, but I'm thinking now that I needed to measure the neutral side instead? The readings fluctuate a little.
Pool light #1 0.25A (big led)
Pool light #2 0.22A (big led)
Spa light: 0.024A (small led bulb)

 

[Wire4money]

What NEC section requires the service plug within 25'?

I have misspoken. There is no service receptacle required for a pool pump in a residential setting. In a commercial setting, 25’.

 

[ajw22]

I have misspoken. There is no service receptacle required for a pool pump in a residential setting.

 

[pcm2a]

I thought I would take a stab at testing the neutral wire, but clearly I have no idea how to do it. The amps read the same as on the hot wire. When I try testing with the voltmeter from neutral to ground it just tells me that they are connected. Doesn't give me any volt reading.

 

[ajw22]

The links in post #24 explain why your regular clamp on ammeter cannot measure leakage. It takes a specialized meter to measure the small amount of current.

 

[pcm2a]

I see, thanks for pointing that out. I guess my next step will be to inspect and replace the spa light, since that is the easiest and cheapest. Inspect before adding in additional GFCI outlets to compensate for the issue.

 

[1poolman1]

I see, thanks for pointing that out. I guess my next step will be to inspect and replace the spa light, since that is the easiest and cheapest. Inspect before adding in additional GFCI outlets to compensate for the issue.

The most commonly overlooked part of a pool/spa light that can cause GFCI tripping is the cord itself. It is sitting in the light conduit that is full of water to the height of the pool water. The cable is of the SJ class (you can look up the ratings), meaning it is a very good cable (think very expensive extension cord) but still affected by long-term water/chemical immersion. The insulation will break down over time and electricity will leak. As it only takes a 5mA (.005 amp) leakage to trip a GFCI, an old light (or one subjected to bad water chemistry) will eventually have this issue.
In the industry, if a light trips a GFCI it gets replaced (after eliminating other possible causes, which take about 10 minutes). Another, not quite as common cause, is the light switch itself, whether a standard switch or a relay in automation. I've found that out the hard way a few times by eliminating all the other possibilities. That's when eliminating the other possible causes took more than 10 minutes.

 

[Dirk]

1poolman1's cable explanation makes a lot of sense. I just want to point out, based on your troubleshooting reports, that you might have more than one cable leaking, explaining why your only getting trips with all three are online. So if it is the cable, just replacing one might not fix the problem. And even if replacing two does (if you happen to stumble on which two are the culprits), you'd have reason to doubt the third one, which might not be too far behind in terms of its failure timetable.

 

[pcm2a]

Update time! This has taken quite a while of slow troubleshooting. What I have done is hook up two lights at a time and run them at night, until they flip the breaker. With only two lights hooked up this does not happen very fast, can be days. Finally I think I had it pinpointed to one pool light. I bought new seals for all three just in case. I took out the one pool light and it was bone dry in the can, the seal also looked as good as new (but I still did not reuse it). Here is where it gets really interesting, I took the led light out and put it in a lamp inside, about the 1/3rd of the leds are flickering or out on the bulb. I put it back in, with the broken leds, and a new seal. After some days the breaker flipped again.

I replaced that led bulb with a new led bulb. All three lights have been running for about three weeks without any issues. Bulb link for reference https://www.amazon.com/dp/B0793SW38V. I paid $42 for it, which seems like a great deal compared to years ago when I paid $100.

Now for my question : why would the led bulb's mechanics failing cause the breaker to flip and why would it take a variable amount of time to happen?

 

[ajw22]

Now for my question : why would the led bulb's mechanics failing cause the breaker to flip and why would it take a variable amount of time to happen?

To fully answer that you need to put a recording ammeter on the light circuit and find out what amps the bulb is drawing over time.

LEDs have electronic circuitry that takes the 120 Volts and reduces it and controls the brightness and colors in the lights. It is usually the electronics that fail in an LED light and not the LEDs. The flickering indicates the electronics had failed. Inexpensive electronic circuitry is sued in a low cost consumer product like that.

Circuit breakers use the heat caused by amps to decide when to trip. That heat can come in milliseconds with very high amps or it can come in hours if the amps are slowly heating up the CB past its trip point.

So the failed electronics were drawing more amps then it should and eventually the CB did its job when heated up past its trip point. That is why you have CBs so that electricity does not start fires by heating up wires past their capacity.