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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. James Avatar

    Can ants in a junction box, along with some moisture cause a 12 volt spa light 100 watt bulb to blow? The multimeter measures a steady 12.8 volts, there is no water in the interior of the fixture however I do get 9 volts if I measure from the receptacle tip to the outside of the fixture housing……6 inch American Standard light fixture with 15 ft cord.

    1. Matthew Simmons Avatar

      Have you just tried the simple trick of putting in a new bulb to see if that solves the issue?

      If the ants find a way to interrupt/overload the circuit, then they might cause an issue.

      1. James Avatar

        Of course…the first new bulb lasted about four on/offs…..the second bulb worked once, then would not light upon the second turn on two days later….so my curiosity is wether ants disrupting this circuit could possibly cause a bulb to blow out or is this light done and need to be replaced for $150 or so? In other words…what issues would wet ants in the circuit box,wire nuts cause?

        1. Matthew Simmons Avatar

          Unfortunately, I am neither an exterminator or an electrician, so I couldn’t tell you with exact certainty what wet dead ants would do to a circuit. But if water got in there it could pop a bulb.

          If the voltage is sturdy, as you say, then there needs to be something else in the circuit (wet dead ants or otherwise) causing the bulbs to pop. Another possibility, though unlikely, is that you bought two defective bulbs in a row.

  2. Eddie Garcia Avatar

    My spa light will come on but my pool light won’t! I have changed out the bulb on the pool light but still nothing!

    1. Matthew Simmons Avatar

      Then it could be fixture cable or breaker issue. Have you checked that voltage is reaching light fixture, per the article?

  3.  Avatar

    I just replaced the bulb in my spa and it seems to work fine for a few minutes then as the water heats up it begins to intermittently go off and on, off and on. Purchased the bulb at a local Leslie’s . It is not tripping the breaker and the switch seems to work fine. Any ideas?

    1. Matthew Simmons Avatar

      Is this an LED replacement bulb or a standard incandescent? With the previous bulb, was this issue popping up?

  4. Sakthi Avatar

    A single GFCI connects the pool and spa light. Pool light works fine but when I turn the spa light, GFCI trips and obviously both the lights done work. I can reset and pool light works just fine.

    What troubleshooting steps should I follow?

    1. Matthew Simmons Avatar

      Does the spa light work fine with the pool light is not on? If the spa light works fine, then you may try changing the breaker. If the spa light trips the breaker even with the pool light off, your spa light cable or fixture may have a short. You will end to to pull the light to check if water is in the housing.

  5. Sandra Avatar

    Hi, I replaced my pentair remote and they did sync it but the spa light only comes on for 3 seconds the shuts off! Any suggestions?

    1. Sandra Avatar

      The pool lights stay on

    2. Matthew Simmons Avatar

      I am not the best with automation, you may want to shoot over to INYO’s Forum for an answer.

  6. Cody Black Avatar

    I just bought my first home and have never owned a pool before. It’s an inground concrete pool. The light in the pool hasn’t worked since I moved in 3 weeks ago so I’ve been trying to investigate this problem. I have taken the entire housing out of the pool and it is so corroded I cannot get any of the housing to come apart and the labeling is all warn to the point of no reading. I want to buy a new housing and fish the wires through to the junction box but I am not an electrician and am not sure to buy a 12v or 120v housing! My local pinch-a-penny only has 12v housings listed as an option. If the housing can put out either voltage and it just depends whats coming from my Breaker to the Junction box. Since this house was built in the 60’s and I don’t see a converter! My guess is everything is 120v. Just really need to know if I can buy any housing? Thank you.

    1. Matthew Simmons Avatar

      The housing accepts the voltage it does not put it out, so you will need to determine the voltage coming from the breaker. A 120-volt circuit will have a line running directly from the breaker to the light or a junction box. A 12-volt circuit will have a line from the breaker routed to a 12-volt transformer then to the light or junction box.

      Walk the path of the light circuit to locate a transformer: if there is no transformer present then you have a 120-volt light. Buying the correct fixture voltage is especially important for LED lights because unlike the incandescent fixtures the bulbs cannot be substituted out to switch voltage.

      To determine a proper light replacement, you will need to measure the outside diameter of the face rim and the depth. Similar to the image of a Pentair Amerilite shown below. Review our light section for lights that have similar dimensions:
      Pentair Amerilite.

  7. VictoriaL Avatar

    PLEASE HELP,
    I was checking my in ground pool light fixture. I have continuity every where except a little silver part (tab) in the very bottom of the fixture, where the bulb screws in, does this mean I have to purchase a new fixture?
    If I have replace the whole fixture which would you recommend?
    Thank you for all of your help,
    Dumb Broad

    1. Matthew Simmons Avatar

      I am not sure what that tab could be. Can you post a new thread on Inyo’s Forum with a picture of the light and tab? Maybe the group of pool owners and techs can figure it out.

  8. Eamonn Avatar

    Hello. My pool light won’t turn off. The switch isn’t like a normal switch. It looks like a low voltage thing. There are several buttons but only one works anything….the pool light. What do you think?

    Thanks.

    1. Matthew Simmons Avatar

      This may be a question better suited for Inyo’s Forum, so you can post pictures of the equipment.

    2. Ed Avatar

      Hi
      When we turn pool lights on they stay on for a few seconds then trip GFI switch everything was working great just started this week.electrican thinks it could be lights

  9. Christopher Chabot Avatar

    The light was installed when the pool was installed, 6 years ago – I know that LED lights should last “a long time”. There does NOT appear to be water in the housing. If it is the light- seems like I will want to wait until the pool is drained below the light case (for the winter)?

    1. Matthew Simmons Avatar

      To me that sounds like a bad bulb, there may be a troubleshooting procedure for your particular model in the owner’s manual or found online. But generally, the LED bulb replacements are almost the same cost of a whole new light.

      To install a new light, you do not have to drain the pool to replace a bulb, read this guide: How To Replace a Pool Light Fixture

  10. Christopher Chabot Avatar

    HI – My LED pool light flashes only briefly when the switch is thrown. I have an Intermatic PX100. When I put a voltmeter on it I get a 120V input line reading and a 12.3V output from the transformer – seems like the transformer is fine. My GFCI is not tripping…
    Thasnk for your help!
    -Chris

    1. Matthew Simmons Avatar

      You may have a faulty light. How long has the light been installed? Also when you pool the light up on your deck, was there water in the housing?

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