Ok, here's my situation - I had a Pentair SAM light that went out last summer, and I waited till this season to replace the bulb. I replaced the bulbs, but the GFCI breaker kept tripping when I put everything back together. There was no water in the light whatsoever (I never put it back in the water). I disconnected the wiring at the junction box, and tried to hit the switch...and the breaker did not trip...so obviously, there was a connection problem between the junction box behind the diving board and the light.
I called an electrician, and they came out to look at it. Essentially, I paid them $115 for them to tell me the same thing (the electricians guess was the trasnformer in the light was busted). I even asked him if he thought that since my pools concrete was sinking at the diving board, would that "pinch" the conduit and cause a short? He said, nope - it didn't appear to have sunk that much to damage the conduit.
So basically, I get the Pentair Intellibrite 5g color light to replace the SAM - mainly so I wouldn't have to change the niche out. So I get in the pool, and TUG as hard as I can on the cable. Nothing. I call a buddy over, and we tie the cable around a 36" crow bar, and we both put our feet on the pool wall and pull with everything we got. The cable snapped, but there's still plenty of slack left (thank God).
My question is, how do I fix this? Tear up the concrete at the diving board, dig up the old conduit, replace the conduit, and replace with new concrete? The concrete only sunk about 1" around the diving board, so it's not extreme, but I think it's enough. I really wish someone would just tell me about some "secret" relief screw on the Pentair niche that would free the cable, but I don't think that's the case (I don't have that star shaped nut in the niche, I checked). But please, someone help!