Troubleshooting an old pool light


May 17, 2015
Munster, IN
Last spring I brought my improperly closed swamp of a pool back to life with the help of the folks on this forum. I closed the pool myself last fall and it opened up crystal clear and trouble free last weekend.

Now I want to get my pool light fixed. I always figured it was just a bulb that needed to be replaced. So I pulled the light out and replaced the bulb, but no dice. I tore open a few of the junction panels/switch boxes where all of my pool equipment is wired up and traced the light cable back to a junction box in the concrete deck of my pool. I found that the junction box was a little wet and the wires (both coming from the breaker and going to the light) were very corroded and disconnected from each other.

I cleaned it all up the best I could and reconnected the wires. I test a full 120v between the junction box and the breaker (so those wires are probably fine) but then I can't get more than about 85-90v testing to the actual light bulb receptacle.

The only conclusion that I can come to is that the wires to the light are corroded causing high resistance on the line, and low voltage to my light receptacle, and therefore no light.

Logically the process for replacing the light seems simple to me but I want to make sure I'm doing it right.

I believe it is a "wet niche" style light where the entire housing and electrical cable is sealed and then screwed into the "niche" in the side of my pool. Is it as simple as pulling the light cable out through the niche, fish some tape thru the conduit into the pool and pull the wire on a new sealed housing back through the conduit and connect? How do I know if a new housing will fit my niche? Are they generally standard for a given diameter?

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
You have a good understanding about it all. The biggest "unknown" in this scenario is almost always the condition of the conduit and how successful you'll be pulling new wire through. Some will use wire gel, but others make sure the conduit is full of water which helps a bit as well. The conduit itself is designed to be full of water up to the point by the equipment pad where the conduit is level with the pool water level. Because the niche is usually full of water, you can see why so many pool owners have a leak where the conduit snaps at the back of the niche and lets water seep out.

Best thing to do with your light itself is look for any kind of model number or something that you can match it up with on-line. Then you can order the correct ring, gasket or any other misc parts required for the job. Hope that helps a bit. Some others may post who have done may light replacements. Good luck!