How to Fix
Your Pool Lights

By Nick Lally

There are several ways to illuminate the pool and pool area. There can be exterior floodlights, landscaping lighting, pole lights, underwater lights and pool house lighting. What we will be reviewing in this article is common underwater lighting in concrete swimming pools. We recommend that someone experienced with these types of lights conduct any investigation and repair.

There may be only one light in your residential pool or fourteen lights in your larger public pool. But they work the same. When the pool was constructed, a light niche was imbedded in the pool wall surrounded by concrete. Light niches can be made of plastic but most commonly they are aluminum.

swimming pool light

The light niche creates a void or space in the pool wall where the fixture attaches from the front side and the light conduit to attaches on the back side. The light conduit is a plastic or copper tube for the electrical supply wire to feed power to the light fixture. It is mostly buried under the deck.

The light fixture is a sealed housing where the light bulb attaches; it has a glass lens. The glass lens attaches to the fixture with screws or a clamp and is made waterproof with a rubber gasket. The supply wire is also sealed to the fixture, which is designed to function underwater. That is why they are called “wet niches”. The inside of the niche is not sealed; it is submerged.

If the pool light is not working there could be several causes. The most common problems can be categorized into two groups. The light is not working and has power; or the light is not working and does not have power. The easier situation to deal with is when the power is being supplied to the light. This means that the problem can be isolated to the fixture or bulb. The corrective action is replacing the either the bulb or the whole fixture. A bulb can cost a lot less than the whole fixture and this is worth investigating first. If it is a simple bulb replacement that has solved the problem, consider yourself lucky, that’s an easy inexpensive correction. But in order to investigate you will need to remove the fixture from the pool wall and disassemble the lens from the fixture to get to the bulb.

The pool light should have been installed with enough extra supply wire wrapped around the fixture to allow the removal and disassembly of the unit on the pool deck without disconnecting the wires from the supply. First make sure the power is of OFF at the breaker panel. If you are not sure how to do this part, it may be time to call for help, a handy pool guy or an electrician. When the pool is full of water, the best way to get the light out of the niche in the pool wall is to use goggles or a underwater mask. Then lay down on your stomach with your arms and head extended into the pool. Your arms should be long enough to reach the attachment screw at the top of the fixture this is usually a Phillips head screw. The goggles will help you see it. Unscrew the top of the fixture and remove it from the niche while unraveling the extra cord and placing the fixture on the pool deck.

Once you have unscrewed the bulb, this will reveal the condition of the fixture itself. Plan on replacing the rubber gasket each time you open up the light fixture, it will likely extend the time until the next bulb replacement.

Once the fixture is disassembled, you will need to inspect the condition of the inside of the fixture. If it looks like there has been corrosion and leaking, only putting a new bulb will correct the symptom not the problem. It is at this point you should strongly consider replacing the entire fixture. This would require a qualified pool mechanic or an electrician. Pool guys don’t mind getting wet, so this is usually the less expensive route.

swimming pool light fixture

If you determine you need a new fixture you will need to purchase the same type of fixture that you currently have. The light fixture needs to match up to the niche in the wall. Make sure you check what the voltage is of your current fixture. The new fixture should come with enough extra cord, if ordered properly, to fit your application. Rather than remove the old fixture and cord entirely, you can use the old cord to “pull” the new cord through the conduit. Simply cut off the old fixture and attach the end of the new cord to the cut side of the old cord at the pool. The power should have already been off when this project began. Now you can disconnect the old cord from supply wires at the junction box. Now you can use the old cord to pull the new cord through the conduit up to the junction box, simply displacing the new cord for the old one. Then you can finalize the connections at the junction box and install the new light fixture on the poolside. You will need the goggles and screw driver again. But to be sure your problem has been solved, quickly test the light while floating in the pool to be sure it works before finalizing the installation. Make sure not to leave the light on too long. If the light heats up and is not submerged you can cause damage.

The second type of problem is when the light is not working and does not have power being supplied to the bulb in the fixture. This will require some testing to figure out. If you properly replaced the fixture already, and it didn’t work, this is most likely the problem. If you have not replaced the fixture there are testing devices commonly use by licensed electricians and qualified pool guys to figure this out. The source problem could be bad wires, or wire connections. It’s kind of like having a bad extension cord feeding the junction box, but it’s underground.

It could also be that the breaker has tripped at the panel. If the breaker switch is a GFCI style switch, pushing the reset at the switch solves the problem. Sometime there are multiple lights on a circuit. If, for example, there were a breaker switch wired to supply a series of lights, then all of the lights in that series would be out at the same time if the problem were at the breaker.

If your underwater lighting is more than a simple bulb replacement, be sure to bring in the pros. It will be worth the time saved trying to figure out what a qualified mechanic already knows.


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