When I purchased my house the light did not function. I found out that it was tied to a GFCI outlet close to my pool equipment and if I reset the outlet it would allow my light to turn on for less then 30 seconds and then trip the GFCI again. After reading online I found information pointing to a leak in the light around the O ring or from the housing itself.
I was also told that anytime you replace the bulb the O ring should also be replaced. I ordered the ring and went ahead and replaced the light. For those of you who have not done this it is very simple. However this did not solve my problem, the GFCI still tripped. I checked the light and no bubbles were coming from the housing and it was as dry as could be.
Then I checked the integrity of the GFCI outlet by plugging a light or a small radio in and seeing if it tripped the outlet. Nope, so the outlet was ok.
I next decided to check the junction box. If you do not know these boxes are set back from your pool in line with your lights. It will have two conduits or pipes running to it. One goes to your light and the other to the wiring of the house.
MAKE SURE TO TURN OFF YOUR BREAKER TO YOUR LIGHT!
A simple flat head unscrewed mine and from the picture you can see there was six wires.
Two were screwed to the junction box I made sure these were tight and secure to the box as they are the ground.
The other 4 were separated and twisted into two pairs.
When I unscrewed the cap you can see that one wire was a frayed type wire and the other was a thick gauge. The thick gauge goes to my house and the frayed to the light. Here is where my problem was, when I went to unscrew one was barely twisted to the house wire and the other had some corrosion in the inner cap. I can only imagine from the chlorine that is coming up the conduit from the light housing.
I took some wire strippers and striped back some fresh wire and twisted securely with two new twist caps. I made sure all was place carefully back and sealed the box up.
I reset the GFCI and the light stayed on for four hours as I enjoyed my first night swim in two summers. I have not had a problem since.
I wanted to write this just in case there was someone out there like myself who was banging their head trying to fix the light and never thought to check the wiring in the box.