1968 was the year that the National Electrical Code (NEC) finally decided to include swimming pools in their standards and regulations (article 680). It has been modified and updated many times since, with the most recent revisions being 2011.

If your pool was built prior to 1968, there likely exists some sub-standard electrical design for your underwater lighting and filter pump. You should update this if it hasn’t been done already.

Seeing a junction box in the pool deck and under the diving board, instead of off the deck, and raised 12” is one such change. Bonding the pool shell, ladder sockets, light niche and pool equipment is also not seen on very old pools.

Most local electrical codes require that electrical work be performed by a licensed electrician. The electrician adds a circuit to the home breaker box or pool sub-panel, and runs power to a junction box, where the wires from the breaker join the wires from the pool light.

Remember that water and electricity don't mix. If you notice anything that looks questionable or possibly hazardous, have it checked out immediately. Every year in the news, there are several cases of fatalities from improperly wired and grounded pool lights.

Underwater Pool Lighting

Underwater lights or UW lights have become a common, standard item in all pools. There are many manufacturers of light fixtures on the market, including Pac-Fab, Paragon and Purex (now owned be Pentair), Hayward, American Products and Swimquip (now owned by Pentair).

At first, all pool lights used an R-40 bulb, a large incandescent flood lamp. In the 80’s, halogen pool bulbs began to gain favor, as well as fiber optic lighting that can run above or below water.

The most popular pool lights in use today have LED bulbs. Now in their fifth generation, LED lamps are bright and colorful. Prices for LED lamps have also come down in recent years, even as the number of LED’s and light output has increased.

Your UW lighting should give you few problems overall. Most incandescent bulbs will burn for 1,000 hours before re-lamping is necessary. LED’s can last 50 years or more. The light fixture and the lamp itself may only last several decades, however, corrosive pool chemistry can weaken the fixture and the screws which hold it together, and this may necessitate replacement. Damage to the light cord can also occur over 2-3 decades, which also necessitates lamp replacement, as a pool light cord cannot be replaced.

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 1-2 seconds without it being fully submerged. The light requires submersion to prevent overheating, and if operated without water covering the lens, the lens will shatter in under a minute.

The lamp or light 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 fixture in place.

In the back of the niche is where the wiring conduit connects from the light niche to the junction box. The junction box is where the wires from the light (load) connect with the wires from the breaker panel (line). An approved junction box, if used, is located at least 4 ft back and 8" above pool water level.

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 R-40, medium based, reflective flood lamps of special design.

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 wipe the surfaces to remove any dirt or grease. Inspect the lamp housing for any signs of warping around the rim, or small pin holes allowing water to get in.

Reassemble with a new bulb and gasket and tighten the bezel securely to the housing to stop any potential gasket leaks. Hold the lamp underwater before reinstalling. If you see a steady stream of air bubbles coming out of the lamp, water is entering the lamp again.

Threaded screw receiver stripped?

On older pool lights, the screw hole at 12:00 can become broken and no longer hold the screw into the light niche. A product called the light wedge can be inserted between the niche and the lamp to hold the light securely in place once again.

Pool bulb burned Out?

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) that fits into a slot on the niche or light housing. You may need to pry and wiggle the lamp to detach the tab and remove the fixture after the screw is removed. Once removed, lift it up above water onto the pool deck.
  3. To get 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 with a #2 or #3 Phillips screwdriver, and for clamp bands use a 5/16” nut driver. After the clamp or screws are loose, remove the light bezel, or light ring. Next, gently pry the glass lens out of the front of the fixture with a small flathead screwdriver.
  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 ¼ turn CCW 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 to prevent injury. After removing the bulb, use the cloth to wipe clean and dry all interior surfaces. Wrap the bulb with a soft cloth, both for safety and to keep finger oils off of the bulb. Thread in the new bulb, specifically made for the fixture, tightening all the way into the base.
  5. Before reassembly, turn on power Very Briefly (for 1 - 2 seconds) to check that the bulb/lamp is working.
  6. Look for printed instructions on the lens for proper alignment of lens to fixture. Reassemble the lens onto the fixture, using a NEW lens gasket. This is the rubber gasket around the lens, of approximately 8" diameter. The gasket fits around the lens only, it does not wrap around the bezel or light ring, and no lubricant is necessary. Complete the reassembly of the fixture by clamping the bezel over the lens with the screws or clamp band. Screws should be tightened in a pattern to ensure even tightening.
  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 made a good seal.
  8. Leaning way over the edge of the pool, 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. A diver’s mask can be helpful to see. Tighten the screw down just snug (not too tight), and then test your light again.

Changed the Pool Bulb but it still doesn’t Work?

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. It’s 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.

It can also happen that new bulbs arrive defective or suffer damage in shipping or handling. Light bulbs can be tested by measuring resistance with an Ohmmeter. Or perhaps you were given the wrong bulb? Check that the light bulb you are using is the correct voltage and wattage for the lamp.

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, but a power issue.

Buying a new Pool Lamp?

If you decide to replace your pool light, you should check a few things in advance of ordering. Some states or counties require pool lights to be low voltage, 12V lamps. 12V pool lights operate with the use of a transformer that steps down the voltage from 120V to 12V. 120V bulbs will not work in a 12V pool, and vice versa, and a 12V bulb will burn out if used in a 120V lamp. The first thing then, is know what voltage your pool light is, 12V or 120V. It will state such on the pool light label.

Secondly, you need to know the distance to the junction box. Pool lights are sold with cords of different lengths, usually in 15’, 30’, 50’ 75’ and 100’. Add up the distance, plus 6-8 feet for the vertical distance and the cord left inside the light niche. If you buy a pool light with a cord that is too short, there is no way to lengthen it.

Third, your light niche is a specific size, so try to replace with the same lamp, or one of the same size, so the lamp will fit the niche. If upgrading to an LED color pool light, check the specifications to determine that it will fit into your light niche.

Related Product Pages:

Pool Lights
Junction Box
Light Bulbs
Light Wedge
Light Niche

Related Blog Posts:

All About Pool Light Bulbs
How to Replace an Underwater Pool Light
Install LED Pool Lights This Weekend!
Swimming Pool Lighting: Care & Repair
The Dangers of Underwater Pool Lighting