Pool Lights


1968 was the year that the National Electrical Code (NEC) finally decided to include swimming pools in their standards and regulations (article 680). If your pool was built prior to 1968, there likely exists some sub-standard electrical design for your underwater lighting and filter pump. You may wish to update this at some point for safety reasons.


Most local electrical codes require that electrical work be performed by a licensed electrician. The electrician wires it up to the breaker box or sub-panel, and then take it from there to the load.


Remember that water and electricity don't mix. If you notice anything that "looks" questionable or possibly hazardous, have it checked out immediately.


Underwater Lighting


UW lights have become a common, standard item in all pools. There are many manufacturers of light fixtures on the market, including Pac-Fab (now owned be Pentair), Hayward, American Products and Sta-rite (now owned by Pentair). Smaller, halogen lamps are now being installed, as well as fiber optic decorative lighting that can run above or below water.


Your UW lighting should give you few problems. Most bulbs will burn for 1,000 hours before re-lamping is necessary. The light fixture itself can last several decades, however, corrosive pool chemistry can weaken the fixture and the screws which hold it together, and this may necessitate replacement.


The light fixture is gasket sealed to prevent water from reaching the bulb behind the lens, however water surrounds the entire fixture, keeping it cool. Do not operate the light for more than one second without it being fully submerged. The light requires submersion to prevent overheating.


The fixture sits inside of a "bucket" turned on its side, towards the pool, called the light niche. The niche is larger than the fixture itself to allow room for several feet of cord to be coiled up behind the fixture. The excess cord makes it possible to bring the fixture up on deck for service and repair. The light niche also provides the threaded hole that accepts the screw which holds the light into place. In the back of the niche is where the wiring conduit connects from the fixture to the junction box, located at least 3 ft back and 18" above water level. The junction box is where the wires from the light (load) connect with the wires from the breaker panel (line). This box should be water and child proof.


Light doesn't turn on?


Check all breakers, fuses, switches and Ground Fault Circuit Interrupter (GFCI) outlets. Frequently, a GFCI outlet is wired into the UW light circuit. If the GFCI 'red button' has popped out, the power will not continue on towards the light. Ensure all of these switches are in the ON position. If you find that a breaker or fuse or GFCI continues to trip, and the light will not come on, you should call for service at this point to determine where this irregularity is originating. If all switches are on, but we have no light, we'd want to remove the fixture from the niche and inspect the bulb for continuity (Of course, we have turned all switches / breakers OFF at this point). Burnt bulbs are replaced with identical voltage bulbs of either 12 volts or 120 volts. 12 volt bulbs are 300 watts, while 120 volt bulbs are available in either 300 or 500 watts. These are medium based, reflective flood lamps of special design. Do not use your garden variety flood lamp bulb.


Water behind the lens?


This is a startling observation for many to see. Many times the lamp continues to burn even with water surrounding the bulb. If you notice a line of water in the lens, the fixture should be removed. Allow the lamp to dry out and replace the gasket.


You may notice one hot summer evening that the pool light has attracted bugs all the way to the deep end!


To change an underwater light bulb, here's the process:
  1. Shut off power at the breaker, and also at any other switches.

  2. It is not necessary to lower the water level. Most all light fixtures have enough cord coiled up inside of the light niche to allow the fixture to be brought up onto the coping stone for repair. Remove the single stainless steel screw at the top of the light (at 12 o'clock). Once this is removed, use a flathead screwdriver to pry the fixture out of the niche. Most fixtures have a tab at the bottom (at 6 o'clock). You may need to pry and wiggle in the direction of the tab to remove the fixture. Once removed, lift it up onto the coping stone.

  3. Now we will go inside of the fixture. Use quality tools of proper size, so as not to strip any of the soft metal screws, bolts, etc. On very old fixtures, screws may break easily, or be corroded from years of water and chemical exposure. Old model lights have 8 brass screws around the fixture, which tighten down on tabs. Newer models have a clamp band with only one screw or bolt/nut. Remove the screws or clamp and gently pry the glass lens out of the front of the fixture.

  4. After the lens is removed, remove the bulb. Most will twist out counter-clockwise. Some spa lamps or small halogen lamps for pools have small bulbs that you need to push in and then twist to remove. Whatever it's type, be careful in removing the bulb, old bulbs may break at the base during removal. It's good practice to cover the bulb with a soft cloth before turning it (counter-clockwise to remove). After removing the bulb, use the cloth to wipe clean and dry all interior surfaces. Thread in a new bulb, specifically made for the fixture. Don't use something other than the real thing.

  5. Before reassembly, turn on power Very Briefly (for 1 - 2 seconds) to check that the bulb/lamp is working.

  6. Reassemble the lens onto the fixture, using a NEW lens gasket. This is the rubber gasket around the lens, approx 8" diameter. Complete the reassembly of the fixture. Make sure screws are very tight. Follow any printed instructions on the lens for proper alignment of lens to fixture.

  7. Place light under water and check for air leaks (a few bubbles may come off of the fixture ring). If you have no bubbles streaming out of your gasket, you have a good seal.

  8. Replace the fixture into the niche. First coil the cord around the back of the fixture, then locate the bottom tab (on the fixture) and tab receiver (on the niche). Line them up and insert the tab into position, and push the fixture flush into the niche. Then it's just the "not always simple" task of getting the top screw back in through the light bezel ring and into the threaded hole in the niche. Tighten screw down just snug (not too tight). Test your light again.

If you change the bulb but the light still doesn't work, use a test meter to check power at the breaker, switches and junction box. (The junction box is usually located off the deck, about a foot high {except on very old pools} near the light. A small box, about 4" x 3", with conduit pipes running up into the bottom. Many times they are behind or under  the diving board.)

Some would say, however, that before you change the bulb, you should make sure there is power all the way to the bulb. Because you may not have a bad bulb at all.


Re-lamping the fixture:


Bulbs used in this application are not cheap. They average $25 each! A gasket is around five bucks. Re-lamping is usually done in under an hour.


Replacing the fixture:


If corrosive water has eaten away at the fixture, or the cord and connections have become damaged, or if the junction box is being moved, a new fixture is in order. New fixtures cost about $195. Labor is usually one hour.