i have underwater lights 1 keeps going out but the other 3 are fine why?

Question

all 4 are on the same wiring harness.

Answer 1

You dont say what kind of lights they are, but if they are hologens then the problem is that you are touching the glass w/o gloves or a clean rag , etc. the oils from your skin will heat up on a hologen lamp and cause it to burn out.

Answer 2

The long and short of this problem is water is leaking in the fixture causing a short