Light fixture leaking? - questions

rhythm said:

Hello,

I pulled my light fixture yesterday because I could see some water behind the glass. Less than a year ago I replace the bulb and put on a brand new gasket. I was pretty careful to follow all of the steps properly. Because the gasket was new, I'm wondering if my fixture is now leaking. Before I put on a new gasket and put the fixture back in the water to check for air bubbles escaping, I wanted to post this picture of the inside back of the fixture and ask if this looks like where the problem could be. There's a thin black layer of 'something' that seems to have been flaking/chipping off over the years and I don't know if this is a leak spot or not.

Thank you,
Greg

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Get a silicone gasket for the light. Install the bulb, gasket, lens, tighten the clamp so that the ends nearly touch. Place the assembly in a bucket of water and turn it on. Watch for bubbles. I do that even with new lights, just to be sure.
Black "stuff" is the edge of the potting compound at the socket that is coming off. A 300 or 500 watt incandescent bulb gets very hot and that compound gets damaged after a while. To save energy, and the fixture if it isn't leaking, get an LED bulb. They are worth it, especially pure white.

Yes, potting compound that can flake off over time. Mine does it too and my picture would be similar to yours, except I'm not getting any water intrusion. I have some flaking even though I have used very low power LEDs for years. Might just be fatigued compound, vibrations over time, etc., but I would want to believe there is enough of the compound originally poured that it can handle some flaking without letting in water. I wonder about the water source and whether next time it might be worth saving it and testing to see if it's pool water (eg chlorine content) or perhaps ground water seeping in. That leads me to ask about your picture that seems to show an open pipe (copper?) coming through. I'm not sure what that pipe is for, and whether ground water could intrude through it. I don't have such a pipe.

Another thing and I'm not sure why @1poolman1 didn't mention it - maybe there is a reason. But when I service the light I carefully clean all surfaces that come in contact with the gasket, sanding any crud away with fine sandpaper or emery cloth, then wiping gasket and surfaces to be perfectly clean. Most gaskets that I've worked with are also stamped with which side should face the pool - hard to see the stamping but it's there, at least on ones I've used. And perhaps more important than any of that, I coat the gasket and metal contact surfaces with magic lube or equivalent, then tighten clamp very far as @1poolman1 wrote. I coat all screws with magic lube too, in hopes of making it easiest next time. Contrary to most recommendations I usually re-use the gasket, again with no leaks (yet!).

Tough to tell from that new picture if that is truly a seam in the assembly - or just some crud that got there off the coiled wire. Mine has no such uniform "seam" - just some misc crud and scratches. Maybe sand on it a bit and see if the assembly looks to be seamed there?
Edit: I just realized I was a bit "all wet" about the "pipe", since it's in the socket luminaire assembly, not through the niche, sorry. So groundwater would not come through there, but I still don't know what the pipe is for, unless the picture is misleading me.

rhythm said:

One last thing, can water be getting in through here?

Thanks,
Greg

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Not sure, but I always seal that area with silicone sealant when servicing a light. If water can get in, it will. There are no seams in a metal light fixture.

rhythm said:

I'll go ahead and use a sealant in and around that cord area that is shown in the second picture. Anything specific that I need to make sure I buy, or avoid?

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I use a clear RTV sealant like this from Home Depot (don't use it on the gasket):