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)

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The Easy

Loose FixtureLOCK SCREW

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.

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 POOL LIGHT LENS GASKETthe 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.

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…

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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.

TRIPPED BREAKERBefore 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.

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

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.

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274 thoughts on “Tips for Troubleshooting Your Pool Light

  1. Hello, so I have an old pool built in the 60’s the light is a purex which I’ve learned is obsalete. Parts are few and far between for it. Question is I have power at the switch but no power at the light fixture. The switch is located approximately 6-7 feet behind where the light is located. There is not an external junction below the diving board or gfci breaker. So I’m trying to figure out the issue I’ve bought the new bulb an rubber gasket that goes around the glass lense

    1. So update I just flipped the breaker and no power at the switch now after I flipped it back on power at the switch again but still not at the fixture. I have a new socket I’m going to try and see if that is the problem or replace the switch. Any other ideas?

      1. So final update I put the new lens gasket on and new light bulb and reassembled the fixture and screwed it back into the nitch light turned on. I was hoping that it was grounded and apparently it was

        1. Sorry, I couldn’t get to this in real-time, Jeremy; but thank you for giving us updates on your troubleshooting steps.

          Was the fix that the light needed a new bulb or did you do other work on it? In your second comment, you said you got a new socket, did you mean bulb or did you install a new socket into your fixture?

  2. Whenever I turn on the lights in my pool I hear a loud grinding noise. The light bulbs are working. Any idea what causes this? Thank you!

    1. I tried googling this issue because I have never heard of it happening. The only stuff that came up were old forum posts about Pontiac Firebirds. I don’t think the causes would carry over into this situation. I would call an electrician.

  3. Hello, we have colored pool lights and it seems to be stuck on one color. Do you know what can be causing this and how it can be fixed?

  4. Hi Matthew,
    My pool light goes out every year. Once a year. We use the light less than 10 times a year. But as soon as I replace the bulb, it works. So something is causing my bulb to burn out. Any ideas? I couldn’t find that specifically in your article or any of the questions.
    This is the third year in a row it has happened on a 6 year old pool. Thanks!

    1. I should add that there is never any water in the housing. My seal is solid and i change the gasket every time.
      Thanks.

    2. Could be a few things, poor quality bulb, water is seeping into the fixture, or the voltage reaching the fixture is not right. For the poor quality bulb, try a different make and model of the bulb. Do you see any moisture in the fixture for the water in the fixture when you replace the bulb? Also, are you replacing the lens gasket when you replace the bulb? If not, that may be the cause of the repeated bulb failures. Regarding the voltage, if you are handy and feel comfortable doing so, use a voltmeter to measure the socket’s voltage. If the socket voltage is off but more then 10-percent, that would be the issue.

  5. Great article; just what I needed! After trouble shooting with a fresh bulb and checking breakers, I started hunting and finally found a GFCI outlet through which wiring was routed into my pool’s control panel box. It had tripped, so I reset it and the light came on. Thanks so much!

  6. Hello I have 3 Colorlogic lights in my pool. 2 small in shallow and one large in deep end. The one on the deep end comes on for 30-60 seconds the shuts off. While on it works correct with lgbt colors and so forth. What do you think it might be? Is this a dead giveaway for. Certain problem? Thank you for your help in advance.

    1. I can give you hints on what it may be, but nothing is a substitute for actually inspecting and testing the circuit for continuity. The light that only works for a minute could be caused by the light not receiving enough voltage from the breaker.

  7. I have a question that I cant seem to find an answer online to, Our pool light is on but it is super dim, you can barely see it. I can flip the switch off and the light still stays on, still dim but it will not go off. It is a ColorLogic LED. Any ideas? Bad switch?

    1. Some LED lights have thermal protection, to prevent the bulb from overheating and damaging itself. The Colorlogic thermal protection dims the bulb if the internal temp exceeds 70 degrees Celcius. You may have a circuitry issue. Low circuit voltage can cause a higher draw in amps, which will raise the internal temp. I would start by testing the line voltage.

  8. My pool light works of a photocell at dark and had been working fine for years… Now i notice it “strobes” when it comes on?? The strobe is a constant pulse every 3 seconds… ????? I didn’t do anything different…

  9. So my lights come on but very dim and lately 2 of the three lights will light up periodically at full brightness but then back dim again.. I don’t know where to even start with this scenario.

  10. Hey Matthew

    I have a 4- year old pool with 8 LED lights. Every light has filled with water and needs to be replaced. Two lights have filled with water and been replaced multiple times, with one light having been replaced 4 times in 4 years. Am i just having bad luck or is there possibly something more systemic going on. the lights are all Pentiar.

      1. thanks Matthew. so they had to do an acid wash shortly after the pool went operational, would that have damaged the gaskets?

  11. My pool lights have stopped working. They are multicoloured LED light types. I normally operate them via the chlorinator go App. Once I switch them on, I get a buzzing noise on the control panel but the pool lights won’t come on. I can’t find any GCFI panels and there’s no trip on my switchboard. The pool pump controlled from the same panel works just fine.

    1. Some things I mention in the article to check: Have you checked to see if there is water in the light? How old are the lights? Have you tried switching the lights to a different breaker to determine if there is an issue with the light or the breaker?

  12. I noticed that there is some water inside one of my pool lights. Is it dangerous to swim in the pool with the lights off?

    1. If the water reaches the socket or any part of the circuit the GFCI should trip ending any chance electric shock. But you may just want to turn it off at the breaker as a preemptive measure.

  13. Hi Matthew,

    I had my pool re-plastered. They redid all my pool/spa light gaskets, and they worked. within 24 hour of my pool being filled with water my spa light fixture filled half way with water. They came out and replaced the gasket again, but still the same problem (half filled with water (visible water line)). Now they want me to buy a whole new light fixture and charge me to replace it. Is it the fixture? Or is it more likely that the gasket was put back on wrong? The light worked just fine until they touched it. I’m just having problems with believing that I need to spend another $500. Advice please.

    1. I think they were just doing something wrong with the gasket installation, there is nothing during the replastering process that I know of that is going to cause the gaskets to go bad that quickly.

      1. That was my thoughts too. I will try to replace the gasket on my own. I find it hard to believe that two gaskets would be bad as this is their job, but maybe they are just trying to get more money out of me. Thank you for the insight and your time and consideration.

  14. Hi!
    My pool is two years old. I have 2 Hayward led lights,one pool, one spa. Separate breakers but same on off button. Spa light won’t come on. Breaker not popped. Should I start with warranty replacement with Hayward or check the transformer. No evidence of Water in bulb. Not sure how long the warranty is from Hayward
    Thank you!!

      1. Just. Recently moved into a home. With a. Pool. Light turns on fine but after about ten minutes the light starts blinking on and off…?

        1. Welcome to the blog, this is a great place to start your research on how to troubleshoot your pool light circuit. Give the article a read and post a comment after you have completed troubleshooting if you have any further questions.

  15. I have the Pentair 5G 12V LED lights attached to my EasyTouch 8. Two lights in pool. One in spa. Each on separate circuits obviously with separate 12V/100W transformers. Spa light suddenly stopped working. Come on sometimes but usually not. Sometimes it comes on one color and just flashes. I’ve pulled the light and see no water inside. I’ve yet to pop open circuit breaker boxes but I can hear the relay in EasyTouch clicking and I feel it at the transformer. These lights are about 3 yrs old. Any thoughts as I stumble through the weeds? I have lots of electrical experience but not pool lights. I’m the one who put them in. Oh what fun that was. Attached nylon rope to old light wires, applied pool grease, pulled very carefully. Attached new wires to rope I pulled through, greased it, slide back through. Not so tough when the run is 10-15 feet away. The one must have gone around the world and back. Straight line to junction box is about 30’. Had to use a 75’ light. Good thing I measured the old cable before buying the new one. I was going with a 50’ until I realized how long that run. Talk about holding your breath if it gets stuck or the rope comes off somehow. Just my experience in case anyone benefits. Right now just need my spa light back to 100% without having to buy and expensive LED board.

  16. Matt,
    About 2 months ago I replaced my pool light with a LED color changing bulb. It had a regular flip light switch. I decided to have an electrician install a Wifi switch for convenience. The old light worked just fine. When installing the new WiFi switch the breaker would continue to trip. Finally found one that worked without tripping the breaker but I noticed when I turned the light on that it was flickering very fast. We pulled the pool light out and there was a little bit of water in the light. The fixture was installed in 2005. Is it possible that it is a breaker issue or is it pretty much a slam dunk that the fixture is fried. We tested the existing fixture with a light bulb and it pops the breaker instantly. I guess my questions are, why did it flicker with the pool light but once we pulled it out and used a test bulb it trips right away. The second is is it possible that it’s just a coincidence that all of this happened when switching the light switch out.

  17. Hi Matt,

    I have an intellibrite underwader pool light and it is stuck on Red only? When I change to another color that color comes on for a second but then switches to solid Red. Any ideas?

  18. Hi, Matt,
    We recently switched over to an LED color changing bulb for our in-ground pool. While we didn’t notice at first, when turned on there appears to be smoke streams emitting from the light (perhaps the fixture itself). We called our local pool technician out who suspected water may be getting in so he resealed. Even after, we are still seeing the smoke streams and our technician is at a lost. GFCI is not tripping, but of course there is some level of concern. Any thoughts come to mind on what might be causing this?

  19. Hi,

    I have a Jandy CPHVLEDS150 pool light. The blue and green colors work, but none of the other colors will come on. Is there a way to just fix those colors, or does the entire light need to be replaced?

  20. Installed a new 12v led. Voltage going into transformer is 120v. Voltage coming out of transformer is 14v. When I turn the switch on to the light, the light works fine. However, when I cycle the switch to change the color of the led light it causes the GFCI to trip. This also happened when I tested the light outside of the pool prior to the install so I know it is not being caused by water intrusion. Thoughts?

      1. Yeah I can but this is one I installed a year ago so seems odd that it would be bad. I can actually cycle the light to change colors by hitting the test and reset buttons on the gfi. Once I get it where I want the light will stay on for hours. It just seems like tuning the switch on at the wall is causing a brief power surge that trips the GFI. What if I switched the light switch with a dimmer and set it to a lower setting so that less voltage would go through when the switch is turned on?

        1. A lot of LED pool lights do not work with dimmers. It seems like the circuit between the Switch and GFI is the issue. I would make sure connections are tight; or replace wires and/of the switch; and be done with it.

  21. Hi Matthew,
    I had a service company come out and install an iaqualink (replacing an RS8). They were able to hook up the pool light but not the spa light (both Hayward colorlogic). They are trying to tell me my 3+ year old spa light needs to be replaced. It worked fine when I closed the pool last year. (The installation was done at the same time pool was opened).Tech was clearly in a hurry and wanted to leave. Any advice in how I can validate. Thanks

    1. Because the ColorLogic is an enclosed system, I’d try hooking it up to a different breaker to confirm if the light is dead or if further troubleshooting is needed. Before switching the light to a new breaker, test the breaker with a voltmeter to make sure it is working.

  22. Hi Matthew,

    Our pool is brand new, job completed this past Jan, 2019. This past weekend we decided to use our pool, we heated it up overnight and at night when we wanted to swim the pool lights were out, we did find the GFCI and it was tripped so we reset it but only the pool light came on and the spa light did not. What could be the reason for this. We tested the GFCI several times to see if the spa light would come on but it never did. Any suggestions?

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