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Tips for Troubleshooting Your Pool Light

A glimmering pool light will add dazzling high notes to your poolscape; but a dim or broken light can leave you in the dark as to how to fix it. When your light goes kaput it is time to roll up the shirt sleeves, pull out the test probes and go to work.

But where to start? That is a tough question, as a pool light can have a hundred or so feet of cable, circuit breakers, GFCIs, and junction boxes to contest with. I’ve learned to start with the easy and then work your way up to the hard. We will walk through some simple fixes and some not so simple.

So, sit back, relax and let us enlighten you. I swear that is the last pun in this blog…

What’s the bright idea? (I lied)

The Easy

Loose Fixture

A pool light, despite all its waterproofing and hundred or so volts of electricity, is held into the pool wall by one bolt called the lockscrew. The lockscrew is located at the 12 o’clock position on the light fixture face. If the fixture wobbles when touched or a strong ripple hits it then a loose screw is likely the cause.

Lockscrew

To fix the issue, dip into your pool with a phillips head screwdriver and tighten the screw. If the screw is stripped or lost, make sure you replace the screw and the gum o-ring.  The o-ring is important to prevent excess water leakage into the niche or housing.

Leaky Pool Light

For the close observing swimmer, you may notice water in the light fixture. Most of the time, this issue is not discovered until the bulb blows. As we all should know, water and light sockets do not mix.

A leaky pool light stems from a bad lens gasket. This part is also called the housing gasket. The heavy gauge rubber ring acts as a clamp seal that waterproofs the joint between the lens and light housing. Chlorine exposure or old age can deteriorate the rubber to warp so that it allows water to reach the light internals. A fixture filled with water can also cause a breaker to trip, so be mindful of that when troubleshooting. Replacing a pools light lens gasket is pretty simple and even the more novice pool owners can do the job.

POOL LIGHT LENS GASKET
Pool Light Lens Gasket

Another less likely cause of a pool light fixture leak is a power cord conduit seal leak. If the conduit seal degrades to that point, the light is likely dead and will require replacement.

Change the Bulb

If your pool light will not turn on and you suspect the bulb, the old shake test is simple enough for  any pool owner to do. The steps on the bulb shake test are simple: remove the light bulb from the fixture and shake it next to your ear. If you hear the ring-a-ting-ting of a broken filament then it’s time for a new bulb.

If the bulb was relatively new before it blew, I would not run out and replace it right away.  A test of the circuitry may be necessary to be certain the new bulb will not be ruined by a power surge or some other electrical issue.  Take a look at our guide on replacing a pool light bulb.

The Not So Easy…

Tripping the Breaker

The dreaded CLICK of a tripped breaker is an annoying and sometimes befuddling event. Annoying because most of the time the reason for the trip is a mystery, unless of course you just plugged in an appliance that overloaded a circuit.

Before we do anything, we want to reset the breaker and also restore the circuit to the point before the trip. To perform the latter, we will unplug any appliance that may have immediately caused the overload.

Next, we will reset the breaker at the box. When a breaker is tripped, it flips to an idle position and will not resume current flow until it is completely reset by hand. To reset the breaker, find the flipped breaker, push it to the complete off position and then flip on. If the switch is not completely reset, it will spring back to idle. If you correctly reset the breaker but it continues to flip to neutral, replacing the breaker may be necessary.

TRIPPED BREAKER
Tripped Breaker

Bad Breaker

The actual task of checking the breaker is not the difficulty, mainly because the task consists of touching a couple probes to terminals. The usual hurdle homeowners have to overcome is getting a multimeter to complete the task. Your run of the mill meter can be found at a local hardware store or borrowed from friendly neighbor.

To test a single pole 120 Volt breaker we will need to remove the front panel of the breaker box to access the terminals. Before removing the panel, make sure to mark the switch that handles the light’s load.

The multimeter will have two leads: one Red lead (positive) and one Black lead  (Negative or Ground.)The black lead is connected to COM port and the red to the mAVΩ port, the latter will be touched to the “hot” wire to measure volt load. Set the multimeter to read 120 Volt AC or higher so it can accurately read your breaker.  Touch the red lead to the single pole terminal and the black lead to the neutral base row. The neutral row is normally labeled, but if it is not look for terminal row with the white wires.

Tripping the GFCI

The ground fault circuit interrupter, better known as the GFCI is a safety device used on installations with a higher than normal risk of electric shock. Most homeowners are familiar with GFCIs from their bathroom electrical sockets. The socket GFCI are also used on construction sites where machinery cords could come into contact with water or sheared.

GFCI BREAKER
Gfci Breaker

The GFCI works by reading a circuit’s current for an irregularity that could be a symptom of a shock hazard. A GFCI circuit can be activated by a current change as low as 4 milliamps. Interrupter switches are an absolute necessity for safety at home or work, but that sensitivity can cause a nuisance, quite literally.  A phenomenon known as nuisance tripping occurs when a GFCI trips when it mistakenly reads a current change as a potential shock hazard.

Common triggers of nuisance trips are:

  • Circuits longer than 100 feet
  • Lighting circuits using fluorescent bulbs
  • Permanently installed electric motors, i.e. bathroom exhaust fans

If the above do not apply to your tripping circuit, it may be time to replace your GFCI. Like any electronic component, these interrupter switches have a lifespan and need to be tested monthly to determine their status.

Line Continuity

A pool light may have up to 200 feet of wire running from the power source to the fixture. Within that length of cable, there may be a fault in a junction, the line or the fixture. Checking line continuity is the process of finding the source of a fault in circuit. Again this task can be done with the handy dandy multimeter. We will be starting from a point in which we assume you have already checked the GFCI and breaker as mentioned earlier in this piece.

  • Set the multimeter to read for 120 or 12-volt range for proper readings.
  • Measure line voltage at junction box. A junction box is the point at which multiple electrical device cables can be joined to one main line. Not all applications utilize a junction so this step may not apply.  If the junction reads 0 then the mainline leading to box is malfunctioning. Have an electrician inspect and install a new main line from box to breaker.
  • Remove fixture from niche, then remove bulb from fixture, touch multimeter leads to fixture socket for reading. If the meter reads 0 from the socket, the fixture is dead and needs to be completely replaced.

As you can see the testing of a pool light is straightforward due to the simple nature of its design. One electrical circuit to the fixture allows for a relatively easy troubleshoot without hard labor. As with anything electrical, if you have any questions or reservations, ask a professional before fiddling with live wires. A working pool light is not worth risking electrocution.

author avatar
Matthew Simmons Technical Writer & Pool Product Expert
Swimming pool expert at InyoPools and host of Poolside Chat, brings over a decade of experience in the pool industry.

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279 responses to “Tips for Troubleshooting Your Pool Light”

  1. Gil in AZ Avatar

    Hi! I have a 14 year-old Pentair 120V/100W incandescent, in-ground pool light that trips panel circuit breaker. 10K gallon salt pool. I am tempted to simply replace the fixture due to it’s age… without draining the pool, is it necessary to plug the niche conduit opening with pool putty/epoxy after fishing the new fixture cable through it?

    1. Matthew Simmons Avatar

      Epoxy can be used, but I suggest using a rubber cord stopper. These look like a rubber cork, that has been cored to allow the light cable through. These are easier to install and easier to remove in the future if you are changing the light again.

  2. Kris Avatar

    My color wheel wasn’t working, so I took the pool light out. After finding out that the repair is going to cost more than I would like, I went to put the light back in; however, I had a small amount of water that I could see behind the pool lens. I replaced the gasket, but I consistently am noticing a small leak behind the pool lens. I have tried to screw the clamp and make the two sides touch…still leaks. I left about 1/2 inch of space between the two sides of clamp…still leaks. Any ideas as to how I can stop the leak so I can just put the light back into my pool?

    1. Matthew Simmons Avatar

      What kind of light is this, a Pentair SAM Light or some kind of fiber optic cable light?

  3. Curtis Avatar

    Hello Matt,

    My inground pool light comes on for somewhere between a few second and a minute then goes out. I wait awhile with the switch off then turn it back on and the same thing happens. I checked bulb wattage (100W) which is what the transformer is rated for. I checked J-box connections which are okay. Light fixture has no water in it and it is submerged. The only other things I can think of are a bad transformer or light fixture thermal protection. Your thoughts?

    1. Matthew Simmons Avatar

      Have you tested the voltage that is at the socket end? The wire connections could be good but a bad transformer is causing something to go wrong. Try a new bulb, just to eliminate that element.

  4. Lauren Avatar

    Hi Matt,
    I just purchased a brand new LED 35w light bulb to replace my old inground, burnt out halogen pool light bulb. I switched on the breaker and light switch, the light did not turn on. I can not reset the gcif, (the red and black button) is stuck and won’t “click” in. I’ve test the electricity in the outlet next to it, and it is working. Could I have a bad Gcif?

    1. Matthew Simmons Avatar

      It could be a bad GFCI, change it out and see if it fixes it.

      The only other thing I would check is if there is water in the light fixture. If water is in the fixture, that is causing the short.

  5.  Avatar

    Is there a way to test the pool while the lights are on to make sure no one gets a shock while in the pool??

    1. Matthew Simmons Avatar

      Yes, it is called “hire an electrician” it is a costly method, but the safest.

  6.  Avatar

    Hi Matt, my bulb I just bought will not turn on, my buddy checked the fixture and it had 13 v running to it but the light would not fire in, the bulb is 12v new

    1. Matthew Simmons Avatar

      What kind of bulb is it? If it is an incandescent then shake the bulb, and listen for a loose filament. If it is a LED, it may be defective; depending on the manufacturer, they may have a way to troubleshooting the bulb.

  7. Cass Avatar

    Installed an led light in a pentair housing. The bottom row got wet as water seeped in through the gasket. Only one day went by before I pulled the housing again. About 10 of the individual led’s no longer function. Will they come back after drying out, or are they gone for good?

    1. Matthew Simmons Avatar

      That is a wait and see game. You will have to give it time to dry out, and hopefully, the circuits can regain their pre-soaked integrity.

      If it works for an iPhone it may just work for a LED light.

  8.  Avatar

    Just recently replaced my existing 120V bulbs with 120V LED’s and outside of the pool the lights worked perfectly. Once installed underwater in their sockets, they do not work. I assumed a leaky gasket and removed them back to the pool deck where they are bone dry internally. Powered back on and voila! Lights work……back underwater and nothing. Any clues as to what the culprit might be as I am befuddled and I am fairly experienced and familiar with electrical circuits.

    Thanks,

    Chris

    1. Matthew Simmons Avatar

      Are the breakers tripping when the bulbs are not working underwater?

      The hole in which the light fixture cable enters the light fixture, is it completely sealed? Does it seem irregularly loose?

  9. Kimberli Avatar

    Hi

    I have a Hayward Colorlogic light in my pool that will not come on. What steps do I take to make sure it is the light and not something more?

    1. Matthew Simmons Avatar

      We cover the steps in the article, please have a read.

  10. Michelle Avatar

    My pool light will go on and off by the remote, However it will not change color anymore. Any suggestions?

    1. Matthew Simmons Avatar

      What is the make and model of the light and remote?

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