I think the underground power lines to me light have collapsed/been compromised. After heavy rain saturates ground, GFCI trips after a bit when pool light turns on. Yeah, run all the wiring underground to hide...seemed like a good idea 18 years ago...now, not so much.
Anyway, just gonna run new conduit from control/switch to pool light junction box. No big deal, black, white, green to light junction box, connect as they were before. What to do, however with the wet-niche insulated #10 AWG bonding wire coming out of conduit into the pool light junction box? Previous config had it pigtailed in with green wire from light cord, run to outlet box next to light junction box, terminated at lug in outlet box. Since i'm eliminating the outlets in the run from GFCI to light junction box, the outlet box with the terminating lug will no longer be there to terminate niche bonding wire. Pool light junction box has never been true 'pool light junction box' but rather a 4x4 PVC junction box with no internal grounding lugs.
It all passed county electrical inspection back in 1998 so it musta been 'OK' back then...