Troubleshooting inground pool light

[schooled by pool]

I had a persistent problem with my pool light. If it was on for 15 minutes or so, it would trip the breaker. Eventually it burned the bulb too, after less than a year of infrequent use. Today, I pulled out the light to replace the bulb. There was no water in the light.

After replacing the 500 watt bulb, I decided to time exactly how long the light would stay before tripping the breaker. But now, the breaker switch immediately trips when I turn on the light. Even when I remove the interrupter, and wire it directly from breaker box to light, it trips the second I turn on the power.

So, removing the possibility of a bad switch/interrupter, and blown bulb, I am left with possibilities of a bad breaker switch, or bad wiring, or replacing the light itself, which is an old swimquip.

Where should I start?

 

[kadavis]

You would have to locate the pool light junction box and disconnect the light from source wire. Make sure Power Is Off at breaker. Check the the light black wire to ground with ohm meter should be open, then check white to ground should also be open. If you have any continuity light fixture is bad. Then disconnect source wire from breaker, also disconnect white wire and ground, at junction box check black and white, black and ground, and white and ground with ohm meter. There should be no ohm readings. If you are unable to do these tests consult a licensed electrician

 

[max2k]

I had a persistent problem with my pool light. If it was on for 15 minutes or so, it would trip the breaker. Eventually it burned the bulb too, after less than a year of infrequent use. Today, I pulled out the light to replace the bulb. There was no water in the light.

After replacing the 500 watt bulb, I decided to time exactly how long the light would stay before tripping the breaker. But now, the breaker switch immediately trips when I turn on the light. Even when I remove the interrupter, and wire it directly from breaker box to light, it trips the second I turn on the power.

So, removing the possibility of a bad switch/interrupter, and blown bulb, I am left with possibilities of a bad breaker switch, or bad wiring, or replacing the light itself, which is an old swimquip.

Where should I start?

your breaker has built in GFI which trips when it senses electrical leak from light wires to the ground. There's possibility you won't be able to disconnect power cable from the light fixture as often times it is single assembly. You can turn the breaker off and try to measure resistance to the ground from one of the light wires at the breaker. It should be open circuit as was already mentioned. I went through this with my original lights which came with the pool- both had electrical leaks in their power cables and I had to replace them both.

 

[schooled by pool]

Thank you for your help. I will get an electrician to do that. But, at least I know where to start and what to ask of the electrician.

 

[schooled by pool]

Thank you too, max2K. I'll look into it. Both you and kadavis seem to be suggesting that I start with the GFI and power source, before the light itself. That gives me a beginning point. Thank you.

 

[gwegan]

Schooled:

Actually kadavis is suggesting tests for the actual light fixture and the cord that attaches to it. That is usually the source of the problem. You most likely need a new fixture. If the breaker trips only when you turn on the light then it generally means a bad fixture, but it could be a bad cord (still a fixture problem) or a problem in the junction box.

You state the breaker is tripping and mention an interrupter. I don't know what an interrupter is. Do you mean a switch? Does the circuit breaker have a (usually white) test button?

 

[JamesW]

I think that Interrupter means a gfci in series after the breaker. Some lights are wired with the gfci in the breaker and some are wired with a gfci after the breaker but before the light.

I would suggest opening the junction box and disconnecting the light from the power. Check continuity from the black and white light wires to the ground wire. Any continuity is bad.

Check continuity between the black and white light wires. It should be about 4 ohms. If it's 0, then you have a short.

Then connect a different load to the power at the junction box to see if the source will support a known good load (lamp etc).

If the breaker is tripping right away with no gfci, then you probably have a direct short to ground or a bad breaker.

If the supply supports another load at the junction box, then that would point to the light as the problem.

If the breaker trips with an alternate load at the junction box, then that would point to the breaker, switch, gfci or wiring to the junction box.

 

[schooled by pool]

Thank you for your help JamesW.

- - - Updated - - -

Yes. The by interrupter I mean on/off switch. The breaker has a red Test Button. It is a GE-Q-Line-20-Amp-Single-Pole-Ground-Fault-Circuit-Breaker-THQL1120GFP. $52.47 at Home Depot. When I looked at the breaker and in the junction box, I did not see any visible signs of bad wiring or faulty switch. But, that is not scientific, only a quick "eye test".

 

[schooled by pool]

Schooled:

Actually kadavis is suggesting tests for the actual light fixture and the cord that attaches to it. That is usually the source of the problem. You most likely need a new fixture. If the breaker trips only when you turn on the light then it generally means a bad fixture, but it could be a bad cord (still a fixture problem) or a problem in the junction box.

You state the breaker is tripping and mention an interrupter. I don't know what an interrupter is. Do you mean a switch? Does the circuit breaker have a (usually white) test button?

@kadavis & @gwegan, I took this advice, and bought a new Swimquip 05086 light fixture. When my pool was reopened, I installed the new fixture, and viola! The light works and it no longer shorts out. Thank you to all who weighed on on this thread last year. TFP is 2 for 2 in helping me troubleshoot problems....suction side air leak at plugs on my pump and the pool light. Thanks!