I recently was asked to relocate a deck box for an in the ground pool. To do this I needed to bend the brass pipe down and extend it with another stick of brass and install it into a deck box. Problem is when I bent the pipe I created a flood. I told the homeowner that he needed to reduce the level of the water and have the light fixed. I thought it was leaking. When I spoke to the pool installer he told me that the light was supposed to leak, that is what keeps the lamp cool. Question is: Am I being hosed? Is this true? This is a 120volt light in the pool. Something doesn’t add up. 120volt and water.. Am I whacked or what???
He's right. It's a wet-niche which means that the Fixture housing is in water. It is a sealed fixture. There is water inside the conduit up to a point even with the water level of the pool. This is why the Deck box must be up higher than the maximum water level or else the box would have water in it.
Wet niche light fixtures come with a cord attached. You have to install the j-box close enough to allow the light fixture to be removed from the niche, set up on the pool deck (while unwinding the cord) then open up the fixture to replace the bulb. The cord usally will not reach to a pool house. This is why the pool junction box is located as close as 4 feet from the pool edge and is to be 8" above the max water level. This allows you to change out the bulbs without draining the pool. The only service call I know of where you get paid to go swimming.
You have to be careful with these lights too. We've had instances of the chlorine eating away the mounting hardware and the light floating to the top of the pool. This can cause the light to explode when parts of it are no longer surrounded by water. They're sometimes a fun way to break up your day if you get to go into the pool.