Replacing a burned-out pool light bulb is a job most homeowners can DIY in under an hour without draining the pool. The trick is doing it safely — pool lights run at 120V (or 12V) and water plus electricity is a serious combination. Here’s the step-by-step.
Important: shut off power at the breaker
Pool lights are GFCI-protected, but the wiring inside the niche is still energized. Always shut off the dedicated pool light breaker before unscrewing anything. Verify the light is off by looking at the bulb — even a faulty bulb should be cool to the touch after 30 minutes.
What you’ll need
- Replacement bulb matched to your fixture (Hayward Astrolite uses S11 bulbs; Pentair Amerlite uses similar)
- A flathead screwdriver
- A towel and waterproof container (the fixture comes out of the pool with you)
- Replacement lens gasket (always replace)
Step-by-step
Confirm with a voltage tester on the light fixture wiring.
Most pool light fixtures have a single screw at the top of the lens ring. Unscrew it and pull the lens off — the fixture pulls out of the niche on its own cable, leaving enough slack to bring it to the pool deck.
Pull the fixture and cable out of the niche. Place it on a towel on the pool deck. Don’t lay the fixture in standing water.
Unscrew the lens retaining ring. The lens lifts off. The bulb screws out of a standard screw-base socket (most pool lights are Edison-base; some are bayonet).
Match wattage exactly. A pool light fixture rated for 300W with a 500W bulb will overheat and crack the lens or short the wiring. Most residential fixtures take 300W–500W incandescent OR a corresponding LED bulb (~40W LED replaces 300W incandescent).
This is the part most owners skip. The old gasket has compressed and won’t seal again. Replace any time you open the fixture. Apply a thin film of silicone pool lubricant to the new gasket.
Put the lens back on, tighten the retaining ring evenly (don’t over-tighten — you’ll crack the lens), and reinstall the screw. Restore power and verify the bulb lights. Then power off again.
Coil the excess cable inside the niche behind the fixture — never pull it out tight. The slack is there for future maintenance.
Push the fixture into the niche, reinstall the top retaining screw, and tighten just enough to seat the gasket. Restore power and confirm the light works underwater.
Upgrade to LED while you’re at it
If you’re already pulling the fixture out, this is the cheapest time to upgrade to LED. Drop-in LED bulbs replace 500W incandescent with 40W LED — same socket, dramatically lower energy use, longer life. See our LED upgrade guide (or just search Pool Light on the PST catalog).
Hayward ColorLogic 4.0 LED 12V
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Hayward ColorLogic 4.0 LED 115V
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PAL Treo Retro Multi-Color Nicheless
Shop NowNeed help matching a replacement bulb or full LED upgrade to your existing niche? Send PST Pool Supplies a photo of the fixture out of the water and we’ll match the right part.