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How to fix LED lights flickering. Most fixes start with the dimmer.
LED downlights flickering at the same time every night? Lights that only flicker when dimmed below a certain level? Or constant flicker that no globe swap fixes? There are three causes, and three fixes. In most Australian homes, the answer is the dimmer.
This article walks through the three most common causes of LED flicker in Australian homes, what to check first, and where PIXIE's smart dimmers, with built-in RippleShield, remove the problem altogether.
Two minutes on what causes LED flicker.
Before the troubleshooting list, here is the short version on screen. The same three causes, explained quickly.
It is not the LED. It is what is feeding the LED.
LEDs work very differently from the old halogens, incandescents, and CFLs they replaced. A halogen glowed because of a hot filament, and the filament's thermal inertia smoothed out any tiny variations in the supply. The eye never saw the noise.
An LED has no filament and no thermal smoothing. It responds instantly to the current it receives. If the supply is noisy, or the dimmer is incompatible, or the load drops below what the dimmer needs, the LED shows it as visible flicker. The noise was very likely there all along. The old globes just hid it.
Three questions narrow it down quickly.
Almost every flicker problem in an Australian home falls into one of three patterns. The fix for each one is different, so identifying the pattern first saves time and money.
1
Same time every night?
Flicker that arrives at the same time each evening, especially in NSW or South-East Queensland, points to the off-peak hot water signal in the supply network.
2
Only when dimmed low?
Flicker that only appears below a certain dim level points to the dimmer running out of minimum load, or to a dimmer and LED that are not properly matched.
3
All the time?
Constant flicker, at every dim level, points to a compatibility issue, a wiring fault, or an overloaded dimmer. This one usually needs an electrician.
Off-peak hot water signal. NSW and South-East Queensland.
In NSW and South-East Queensland, electricity suppliers inject a control tone into the supply network to switch off-peak hot water systems on and off. Every home connected to the network receives that tone, whether or not it actually has an off-peak hot water system.
The tone is harmless to most appliances and to old halogen lighting. To LED dimmers without flicker immunity, it looks like a brief power dip, and the dimmer passes it straight through to the LED as a visible flicker. It happens at the same time each night because that is when the network sends the signal.
For years, the only fix was to install a dedicated filter at the switchboard. Around $500+ of hardware, plus an electrician's call-out, and not always a guaranteed result.
PIXIE addresses this with a purpose-built combination: the PIXIE RippleShield Dimmer (SDD400RSBTAM) paired with the PIXIE RippleShield downlight range. RippleShield detects the off-peak signal and filters it inside the dimmer, before it reaches the LED. No add-on hardware at the switchboard, no specialist filter circuit, no service call. This is the only PIXIE pairing that delivers guaranteed off-peak signal immunity.
The RippleShield combination
RippleShield Dimmer, plus RippleShield downlights. Guaranteed immunity, day one.
RippleShield is the technology formerly known as SFI. The SDD400RSBTAM dimmer paired with the PIXIE RS downlight range is the only PIXIE configuration sized and tested to neutralise the off-peak signal in NSW and South-East Queensland conditions. It works on day one with no setup, and without the standard PIXIE Smart Dimmer (SDD300BTAM) being asked to do a job it was not built for.
What the off-peak signal actually looks like.
If you have not seen it on a real ceiling, this short clip from a PIXIE installation shows the flicker in motion, and what changes once a RippleShield-equipped dimmer is fitted.
Below the minimum, the dimmer runs out of headroom.
Every LED dimmer needs a minimum electrical load to operate cleanly. The standard PIXIE Smart Dimmer (SDD300BTAM) operates down to 2 watts, which is well below most LED downlight installations, and lets you set a minimum dim level in the PIXIE PLUS app. Below the minimum, any dimmer struggles to drive the LED smoothly, and you see flicker as you reach the bottom of the dim range.
There are two ways to fix this:
A
Set a minimum dim level
The PIXIE Smart Dimmer (SDD300BTAM) exposes a minimum dim level setting in the PIXIE PLUS app. Set it once, slightly above the flicker point, and the dimmer will never drop below that level. Set and forget.
B
Use lamps for low-light moments
For very low ambient light, like a movie room or a hallway at night, switched lamps on a PIXIE smart power point give a soft glow without asking the downlights to dim into the unstable zone.
There is a wider point here. LED downlights vary widely in how cleanly they dim. Some dim from one to one hundred percent without complaint. Others only behave well with a specific kind of dimmer. Pairing high-quality LEDs with a high-quality smart dimmer removes most of the variability before it starts.
Persistent flicker. Compatibility, wiring, or load.
If the lights flicker constantly, regardless of dim level and regardless of the time of day, the cause is usually one of three things. This is the point at which an electrician is the right call.
1
Dimmer and LED mismatch
Not every LED downlight works with every dimmer. Some need leading-edge, some need trailing-edge, some need a specific minimum load. The PIXIE Smart Dimmer (SDD300BTAM) handles the most common Australian LED downlights, but mismatches still happen with off-brand or older fittings.
2
Wiring fault
A loose connection at the dimmer terminal or at the LED fitting itself can cause persistent flicker. This needs an electrician with a meter, not a homeowner with a screwdriver.
3
Overloaded dimmer
Every dimmer has a maximum load rating. Exceed it and the dimmer overheats, the LEDs flicker, and eventually the dimmer fails. Check the wattage of all the LEDs on the circuit against the dimmer's rated maximum.
A capacitor, also called a load bypass device, can sometimes smooth out a stubborn dimmer-and-LED combination. It costs around $50 per dimmer, plus the electrician's call-out, and one is needed for each dimmer rather than each light. It is a reasonable fallback when nothing else works, but it is treating a symptom. Replacing the dimmer with one that has the right characteristics is usually the cleaner answer.
Two PIXIE dimmers. One flicker problem solved.
PIXIE makes two smart dimmers, designed in Australia, for Australian homes. Between them they cover all three causes, but they are built for different jobs.
For the off-peak hot water signal in NSW and South-East Queensland, the PIXIE RippleShield Dimmer (SDD400RSBTAM) paired with the PIXIE RippleShield downlight range is the only configuration that delivers guaranteed immunity. This is the one to specify for any home affected by the off-peak tone, and the only one to use with the RS downlight range.
For dimming compatibility, low-end stability, and broad LED support everywhere else, the PIXIE Smart Dimmer (SDD300BTAM) covers cause two and most of cause three. Configurable minimum dim level, 2-watt minimum load, and reliable behaviour with the most common Australian LED downlights.
Ask your electrician for the right PIXIE dimmer for the job, and the most common LED flicker complaints in Australian homes usually go away on day one. No filter at the switchboard, no capacitor add-on, no service call.
Flicker is a solved problem. If you start with the right dimmer.
Most flicker complaints come down to a dimmer that was not built for modern LEDs, or, in NSW and South-East Queensland, one that cannot filter the off-peak signal homes receive every night. The PIXIE smart dimmer family was built for both jobs, with a specific product for each.
The PIXIE promise
The right PIXIE dimmer for the cause, matched on day one.
For homeowners affected by the off-peak signal, the RippleShield Dimmer plus RippleShield downlights deliver guaranteed immunity. For everyone else, the standard PIXIE Smart Dimmer handles low-end stability and broad LED compatibility. For electricians and AC installers running PIXIE CLIMATIQ jobs, it means lighting that does not need a separate troubleshooting visit after the climate work is signed off.
End the flicker. Start with the dimmer.
Learn more about PIXIE smart dimmers, RippleShield, and the wider PIXIE smart home ecosystem they slot into.
Product family
PIXIE Smart Switch and Smart Dimmer
SDD300BTAM for general flicker, SDD400RSBTAM RippleShield Dimmer for off-peak immunity
Free service
PIXIE Free Smart Home Design
Send us your plans, we will design the smart home with you
Technical detail
RippleShield (formerly SFI) explained
How the filtering works and why it solves the off-peak signal problem
Read more
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