Pool Light Troubleshooting & Repair: Fibreglass Pool Faults Fixed
Fibreglass pool light not working? Fix common faults - tripped safety switch, failed transformer, water in the lens - and know when it's an electrician's job.
Most fibreglass pool light problems trace back to one of three places: a tripped safety switch, a failing 12-volt transformer, or a perished seal letting water into the fitting. Knowing which one you're looking at tells you straight away whether it's a two-minute fix in the pump shed or a call to a licensed electrician. This walks through how the lights are actually wired during a build, a symptom-by-symptom fault table, and where the law draws the line on what you can touch yourself.
How fibreglass pool lights are wired
Modern fibreglass pool lights run on 12 volts, not mains power. When we build a pool, the light is a sealed LED unit that sits flush against the gelcoat, bonded into a pre-formed penetration in the shell. A low-voltage cable runs from the back of that fitting, through conduit behind the shell, back to a transformer (also called a driver) mounted near the equipment pad. That transformer is the only part that touches 240-volt mains — it plugs into a weatherproof power point, usually on an RCD-protected circuit, and steps the voltage down to a safe 12 volts before it ever gets near the water.
That split matters for every fault below. The 12-volt side — the light itself, the cable, the transformer's low-voltage output — is extra-low-voltage and safe to inspect. The 240-volt side — the power point, the circuit, anything hardwired — is licensed electrical work under AS/NZS 3000. Colour changing is handled by flicking the wall switch or a controller in a set sequence; the light "remembers" its last colour by counting how the power was cycled, which explains one of the more common complaints we hear.
Pool light fault finder: symptom, cause and who fixes it
Start here. Match your symptom, read the likely cause, then check the last column before you pick up a screwdriver.
| Symptom | Most likely cause | DIY-safe or electrician? |
|---|---|---|
| Light won't turn on at all | Tripped RCD or breaker; failed transformer; wall switch fault | Check the RCD and power point yourself; a dead transformer is an electrician swap |
| Flickering or strobing | Loose 12V connection, failing driver, or voltage drop on a long cable run | Electrician — the fault is inside the wiring or driver |
| Stuck on one colour, won't cycle | Colour sequence lost sync from a quick power flick | DIY reset by power-cycling the switch correctly |
| Water or fog inside the lens | Perished face gasket or lens seal | Reseal is DIY-ish on a surface-mount unit; wet wiring is electrician territory |
| One LED dead, a dim patch in the beam | Failed diode cluster inside the sealed unit | Replace the whole fitting — the unit is sealed, not serviceable |
| Green or white crust on the fitting | Chlorine or salt corrosion on the housing | Clean it yourself; corroded contacts need an electrician |
Light won't turn on
Nine times out of ten this is power, not the light. Go to the switchboard first and check whether the RCD (the safety switch) or the light's breaker has tripped — reset it and see if the light comes back. Then check the power point the transformer plugs into; a bumped or weathered outdoor GPO is a common culprit. Both of those are things you can safely check. If power is reaching the transformer and the light is still dead, the transformer itself has usually failed, and replacing it means working on the mains side — that's an electrician.
Flickering or strobing
A flickering 12-volt light almost always means a connection is loose or the driver is on its way out. On long cable runs — a light at the far end of a large pool — voltage drop can also make an LED stutter. None of these are a DIY fix: the fault sits inside the low-voltage wiring or the transformer, and diagnosing it properly needs a meter and someone licensed to open the connections.
Stuck on one colour
This one looks alarming and usually isn't. Colour-changing LEDs step through their sequence based on how you cycle the power. Flick the switch too fast, or lose power mid-cycle in a storm, and the light "sticks" on whatever colour it landed on. Turn the light off, wait ten seconds, and turn it back on cleanly — most units drop back to the start of the sequence. If it still won't cycle after a clean power-off, the controller has failed and needs a look.
Water inside the lens
Fog or standing water behind the lens means the face seal has perished — chlorine and UV eventually harden the rubber gasket that keeps the fitting watertight. Caught early, this is a reseal. Left alone, water reaches the LED and the fitting is done. On a surface-mount fibreglass light you can lower the pool below the fitting, remove the face, and replace the gasket. The moment you find water in the wiring rather than just the lens, stop and call an electrician — wet 12-volt cable can still fault the transformer upstream.
The Australian legal line: what you can and can't touch
In Australia, you cannot legally do your own mains electrical work. Anything on the 240-volt side of a pool light — the power point, the circuit, hardwiring or replacing a transformer — must be done by a licensed electrician. This isn't red tape for its own sake: water and mains electricity around a pool is exactly the scenario AS/NZS 3000 wiring rules are written to prevent, and pool areas carry their own zoning requirements for how close any electrical fitting can sit to the water.
What you can do yourself is everything on the safe side of that line:
- Reset a tripped RCD or breaker at the switchboard
- Check whether the transformer's power point has power (a plug-in tester or another appliance tells you)
- Unplug the transformer to isolate the light before inspecting the fitting
- Reseal or clean the surface-mount light itself once the power is isolated
- Power-cycle the switch to reset a stuck colour
If the fix lives on the 12-volt side and the power is off, you're clear. If it touches mains, book the electrician — and if you're mid-build with us, that wiring is certified as part of the handover.
Replacing an LED in a fibreglass pool
You don't replace a single diode — the light is a sealed unit, so a dead LED means swapping the whole fitting. The job is more approachable than it sounds because fibreglass lights are surface-mounted, not buried in a concrete niche.
Two ways to reach the light:
- Bring it to you. Many 12-volt fittings are installed with a coil of spare cable behind the shell specifically so the light can be drawn up to the coping and worked on above water. You unclip the fitting, pull the slack, and swap it dry.
- Lower the water. If there's no cable slack, drop the pool level just below the light, work on it in place, then top the pool back up.
Either way the sequence is the same: isolate the power at the transformer, disconnect the fitting at its 12-volt junction, fit the replacement sealed unit, reseal the face gasket, feed the cable back and re-mount it flush to the gelcoat. The 240-volt transformer connection never gets touched. If your fitting is hardwired rather than plug-connected at the light, that connection is the electrician's part.
Upgrading halogen to LED
If you're still running an old halogen or incandescent pool light, an LED upgrade pays for itself on power alone. Halogen units draw 300 to 500 watts, run hot enough to cook their own seals, and burn out in a season or two. A 12-volt LED draws a fraction of that, runs cool, and lasts years. It also opens up colour changing, which a halogen can't do without a mechanical colour wheel.
Every pool we build comes with a colour-changing LED as standard, so a new fibreglass pool is already on the efficient side of this. Adding extra lights — a second or third fitting to wash a feature wall or light a deep end — costs $325 installed per additional LED. For a full rundown of why LED wins on cost and control, the benefits of LED pool lighting is worth a read, and if you're weighing up fittings, the types of pool lights worth trying covers the options.
What LED pool lights actually cost to run
A colour-changing LED pool light costs roughly $20 to $25 a year to run. Here's the maths, using a typical 40-watt fitting and Queensland electricity at about 30 cents per kilowatt-hour:
| Light type | Power draw | Cost per night (5 hrs) | Cost per year |
|---|---|---|---|
| Modern LED (colour) | ~40 W | ~6c | ~$22 |
| Old halogen | ~300 W | ~45c | ~$164 |
Run two LEDs and you're still spending less than a single old halogen cost. That gap is the real reason we don't fit anything but LED — the running cost of the lighting disappears into the noise of the rest of the pool. Lighting also does a lot of the heavy lifting once the sun goes down, which is why it's worth planning alongside the rest of the pool landscaping rather than as an afterthought.
FAQs
Why is my pool light not working?
Most often it's a tripped safety switch or breaker, not a dead light. Check the RCD and the transformer's power point first — both are safe to check yourself. If power is reaching the transformer and the light is still off, the transformer has usually failed and needs a licensed electrician to replace.
Can I replace a pool light myself in Australia?
You can work on the 12-volt fitting yourself — swapping a sealed LED unit, resealing the lens, cleaning corrosion — provided you isolate the power first. You cannot legally do the mains-side work: replacing the transformer, touching the power point, or any hardwired connection must be done by a licensed electrician under AS/NZS 3000.
How long do LED pool lights last?
A quality 12-volt LED pool light typically lasts several years of nightly use, far longer than the season or two you'd get from a halogen. The seal usually fails before the diodes do, which is why keeping the face gasket in good condition matters more than the LED itself.
How much does it cost to add a pool light?
An additional LED pool light costs $325 installed. New pools we build already include a colour-changing LED as standard, so this is for adding a second or third fitting to light a feature wall, spa, or deep end.
Why is my pool light stuck on one colour?
The colour sequence has lost sync, usually from flicking the switch too quickly or losing power mid-cycle. Turn the light off, wait about ten seconds, then turn it back on cleanly. Most units reset to the start of the sequence. If it still won't cycle, the controller needs checking.
Is water inside the pool light dangerous?
The light runs on 12 volts, so it isn't a shock risk in the way mains would be — but water in the fitting will destroy the LED and can fault the transformer upstream. Treat it as urgent: isolate the power and reseal or replace the fitting before the water reaches the wiring.
Still stuck after checking the safety switch and the seal? Drop our team a line and we'll help you work out whether it's a fitting you can swap yourself or a job for the electrician.
