Originally Posted by Geomancer
Yes ... and they are designed to be used over a hood, not an open tank. There is a difference.
I'm not saying this is instantly catastrophic, or a guarantee, it's something that happens slowly over time. It might arc, it might burn, it might do nothing. Risk.
I guess ask yourself, why do they make exterior light fixtures if moisture makes no difference? If it's just because they last longer, why do building codes require the use of an exterior fixture?
Perhaps I didn't state it right. My 5 gallon Mini-bow hood WAS meant to be used over open water. It had a really cheap basically pointless condensation "guard" which is what I assume it was meant to do or perhaps to shield the bulb from direct splashes. It did basically nothing for condensation. Other then that it is a standard incandescent dual socket and was wired no differently then any other lamp socket I have seen. Originally it had wire nuts and a extra plastic 'shield' around the base of the wires and base of socket. Neither the bulb guard or plastic shield protected it sufficiently IMO. I completely rewired and modified it from the start. Its safer IMO then it was previously, still I run plastic wrap between the hood and the tank to keep the moisture off it and stop evaporation.
IMO main difference between interior and exterior fixtures is simply testing and perhaps a grounding wire and some small added moisture resistance. There is extra cost to test fixtures in a humid/outdoor setting to make sure they preform thus they are more expensive.
Regardless of the fixture any aquarium should be on a GFCI if you are truly worried about electrical equipment. All but one of my tanks are on GFCI outlets.
If your worried about dangerous malfunction there are many manufactured aquarium fixtures that have done that. My main point is a lot of aquarium hood/lights are overpriced pieces of junk. Odyssea is one brand name of cheap aquarium lights that has a lot of fire reports and other problems in the past.
Then again I am running ballasts that have absolutely no casing on them at all