I have 4 Pentair 120v lights in my pool (3 in pool, one is spa). System control is Jandy Aqualink One touch. Lights are on GFCI circuit from Jandy panel (not GFCI circuit breaker). I also have each of the lights on individually switches, so I can manually turn each light on/off. My lights this winter started tripping the GFCI. Just now warm enough for me to start trouble shooting.
I narrowed problem down to 1 light in pool. I removed it from niche and removed cover gasket. It looked fine. I removed bulb and left in sun for 2 days in case something was wet and needed to dry out. I hoped this would solve issue of GFCI tripping. It did not; with Jandy system lights on, and all other lights working fine, as soon as I turn switch on for this light, it trips the GFCI. If the problem is not water in fixture, then what could issue be? Possible ground wire that is attached to niche corroded or broke?