How to Replace a Pool Light (LED and Incandescent)

A pool light that's gone dim, flickering, or dark usually isn't a sign of anything serious. Bulbs and even LED fixtures wear out over years of use, just like any other light in your house. Replacing one is a genuinely doable weekend project for most pool owners, but it sits at the intersection of electricity and water, so the process is less about wrench-turning and more about doing the steps in the right order. Here's how it works for both incandescent and LED pool lights.

Cut the power before you do anything else

Pool lights are wired on their own dedicated circuit, and that circuit should be protected by a ground-fault circuit interrupter (GFCI). Most local electrical codes require GFCI protection on pool lighting circuits, though exact requirements vary by jurisdiction, so it's worth confirming what you have with a licensed electrician if you're unsure. Before you touch the fixture, find the breaker for the pool light (it's often labeled separately from the pump breaker) and switch it off. Then test the fixture with a non-contact voltage tester to confirm it's actually dead, don't just trust the label on the panel.

Incandescent vs. LED: what actually changes

Older pools typically use standard incandescent (or halogen-style) pool light bulbs, usually in the 300 to 500 watt range, screwed into a niche mounted in the pool wall below the waterline. Many newer installs use LED fixtures instead, which run cooler, use meaningfully less energy, last far longer, and often add color-changing or color-selectable options that incandescent bulbs simply can't do. The good news is you don't necessarily have to replace the whole fixture to go from one to the other.

If your pool currently has an incandescent fixture, look for an LED retrofit bulb rated to fit your specific niche size and voltage before assuming you need a whole new housing. Most residential pool lights run on 12-volt low-voltage systems, though some older pools use 120-volt fixtures, so match that first. Many manufacturers make retrofit LED bulbs designed to drop into existing incandescent niches, which is the simpler and cheaper path. A full fixture swap is really only necessary if the niche itself is damaged or you want features the retrofit bulb doesn't support.

What you'll need before you start

• A replacement bulb or fixture matched to your pool light's voltage (12V or 120V) and niche size, check the old bulb or fixture housing for a model number before shopping.
• A new gasket sized for your fixture. Don't plan to reuse the old one.
• A Phillips or flathead screwdriver, the retaining screw at the bottom of the fixture varies by brand.
• A non-contact voltage tester.
• Silicone dielectric grease for the gasket and threads.
• A helper, some fixtures come out easier with someone holding the cord slack while you work.

Step by step: pulling the fixture and swapping the bulb

• Turn off the breaker for the pool light and verify it's off with a voltage tester.
• Remove the single retaining screw at the bottom of the light fixture, usually accessible from the pool deck or by reaching just below the waterline.
• Gently pull the fixture straight out of its niche. Pool lights are wired with extra service cord coiled behind the niche specifically so the fixture can be lifted up onto the deck without draining the pool or disconnecting any wiring.
• Set the fixture on a towel on the deck, away from standing water, before opening it up.
• Remove the lens retaining ring or screws, take out the old gasket, and swap in the new bulb or LED module, following the manufacturer's instructions for your specific model.
• Seat the new gasket evenly with no twists, then reassemble the lens and retaining ring snugly, not overtightened.
• Lower the fixture back into the niche and reinstall the retaining screw before restoring power.
• Restore power at the breaker and test the light. If it doesn't come on, recheck the bulb seating and the GFCI before assuming the new bulb is bad.

The gasket is the part people skip

The rubber gasket between the lens and the housing is what keeps pool water out of the electrical compartment, and it's the single most common thing people reuse when they shouldn't. Gaskets compress and flatten over years underwater, and a flattened gasket won't reseal properly even if it still looks intact. Replace it every time you open the fixture, not just when it's visibly cracked, and add a light coat of silicone dielectric grease before reassembly. It costs a few dollars and prevents the far more annoying problem of water working its way into the housing and shorting out your new bulb a few months later.

Common mistakes that send you back to the pool deck

• Skipping the gasket replacement and reusing the old one because it 'still looks okay.'
• Running an incandescent bulb out of water for more than a minute or two while testing, the heat can crack the lens. LEDs are generally more forgiving here, but check your model's instructions.
• Overtightening the lens screws, which can crack the housing or pinch the new gasket unevenly.
• Mixing up voltage: an LED retrofit bulb rated for a 120-volt niche won't work safely in a 12-volt system, and vice versa.
• Restoring power before the fixture is fully reseated and the retaining screw is back in place.

Pool lights aren't something you think about until one goes dark, which is exactly why it's easy to lose track of when yours was last serviced. Logging the swap (bulb type, date, and what you noticed beforehand) in Skimmer means the next time something looks off, you'll have a record to check instead of a guess.