Why did my pool light fill with water?

Water gets into a pool light when the seal around its lens or cord fails, and the usual suspect is the lens gasket. If your light has filled with water, switch it off at the breaker, leave it off and have a licensed electrician look at it before anyone swims. Water and the light's electrical parts are a shock risk, and this is not a repair to attempt yourself.

How water gets in

An underwater light is a sealed unit. A rubber gasket sits between the lens and the housing, and the cord enters through a seal. When any of those fails, pool water works its way in, and you see fog, droplets or a pool of water behind the lens.

The best-documented cause is a worn or reused gasket. Pentair's manual tells installers to use a new lens gasket whenever the light is taken apart, and warns that failure to do so may permit water to leak into the assembly.^[1] In other words, the seal is a part that is meant to be replaced, not reused, so a light that was opened once for a bulb or a cord change and put back with its old gasket is a likely candidate.

Other possibilities are a lens or face ring that was not seated or tightened evenly, a damaged cord jacket or cord seal, an old gasket that has hardened with age, or a light that was run out of the water. Pentair warns never to operate its light for more than ten seconds unless it is totally submerged, since otherwise the assembly gets extremely hot.^[1] Which of these applies to your light is something the electrician finds when it is opened.

What to do first

1. Turn the light off at the circuit breaker, not just the wall switch. Pentair's instruction is to always disconnect the power to the pool light at the circuit breaker before servicing the light.^[1]
2. Keep people out of the pool until the light has been checked. A light that flooded may also have lost its protection, and the electrician needs to confirm the circuit is safe.
3. Do not try to open, dry or re-seal it yourself. The rest of this page explains why.
4. Note what you saw: when it started, whether the light flickered or tripped the GFCI, and whether anyone had worked on the light recently. This helps the diagnosis.

Why it is not a DIY job

Pentair's warning about a missing new gasket spells out the consequence: water leaking in could cause an electrical hazard resulting in death or serious injury to pool users, installers, or others due to electrical shock, or breakage of the lens, which likewise could result in serious injury to pool users, installers, or bystanders, or in damage to property.^[1]

Other items in the same manual show why the repair belongs to an electrician. It warns: "Under no circumstances replace lights by splicing wire under water or behind niche."^[1] A flooded light is also the moment to check the supporting electrical protection. Among the requirements Pentair says the pool's electrical system must meet are a GFCI on the lighting circuit for line voltage models and bonding of the light and metal items within 5 feet of the pool.^[1]

What the electrician will decide

Usually it comes down to repair or replace. If the fixture is sound, the pro may be able to open it, inspect it, fit a new gasket and reseat the lens. If water has damaged the electronics, the lens or the cord, replacing the light is the safer answer. See what replacing a pool light involves for how a swap works, and how much pool light repair costs in Virginia for what drives the bill.

Ask for the diagnosis in writing: what was found, whether the gasket and cord seal were replaced, and whether the circuit protection was tested. If the light was flooded after earlier work, say so.

Permits in Virginia

Virginia's building code requires a permit application before installations or alterations involving electric wiring, but it exempts replacement of luminaires (lighting fixtures) in a single dwelling unit.^[2] A repair that only reseals or swaps the fixture may fall under that exemption, while work on wiring may not. Ask your local building department, and ask the electrician whether the quote includes any permit.

When to call a licensed pro

Call one now. In Virginia no individual may work, or offer to work, as an electrical tradesman without a tradesman licence, unless working under the supervision of a tradesman licensed in that specialty.^[3][4] DPOR also says that if the work is valued at $1,000 or more, a valid Virginia contractor's licence is required for the licence category in which the contractor is to work.^[5] Check the business in the DPOR licence lookup before you agree to a price, and read how to check if a contractor is licensed in Virginia.

Until the electrician arrives, leave the breaker off. You can also browse more pool and spa equipment answers or find pool and spa businesses.

To get it fixed, describe the pool light problem and licensed local businesses quote it.