(02) 9662 1517

LED downlight flickering: why it happens and what fixes it

Nine times out of ten it is the dimmer, not the downlight. The rest is loose wiring, a dying driver or a globe that was never dimmable.

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In short. LED downlights flicker for four reasons: a dimmer that was made for halogen and cannot handle a small LED load, a dimmer and LED driver that are not compatible with each other, a loose connection between the driver and the light, or a failing driver. The first two are fixed with a trailing-edge dimmer rated for LED, fitted by an electrician; the last two mean replacing the fitting. Flicker that affects every light in the house at once is a supply problem and a call to your electricity provider.

Is it the dimmer?

If the flicker appears only when dimmed, or only at the bottom of the dimmer's range, it is almost certainly the dimmer. Old leading-edge (TRIAC) dimmers were designed for 40 to 400 watts of halogen; six LED downlights at 10 watts each are 60 watts, close to or below the dimmer's minimum, so the dimmer chops the waveform unevenly and the driver reproduces it as flicker, strobing or a hum. A trailing-edge dimmer rated for LED, from the downlight's own maker where possible, is the standard fix. Look for the dimmer on the downlight maker's compatibility list before buying either.

Is it one fitting or all of them?

One fitting flickering in a group is that fitting: swap it with a neighbour and see whether the fault moves. A driver on its way out often flickers when warm, so a light that is fine for ten minutes and then starts is a driver. If the downlight is a GU10 or MR16 type with a replaceable globe, check the globe says dimmable; many cheap LED globes do not, and they flicker on any dimmer.

Is it a loose connection?

Plug-in LED downlights have a lead from the driver to a socket in the ceiling. A plug that is not fully home will flicker when the ceiling is walked on upstairs or when the fan runs. Pushing the plug in is within what a householder may do; anything behind a terminal block is an electrician's.

When is it the house?

Lights across the whole house dimming or flickering together, especially when the oven, air conditioner or a neighbour's welder starts, is voltage fluctuation on the supply. Note the times and ring the electricity distributor; it is their fault to find.

Where this fits at Cosmo

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91-93 Anzac Parade, Kensington. Monday to Friday 9am to 5pm, Saturday 9am to 4pm. (02) 9662 1517.

From the shelves

LED-compatible dimmers on the shelves

Prices as shown on Cosmo Lighting's store at build time. Product photography from the supplier.

FAQ

LED downlight flickering questions

Why do my LED downlights flicker when dimmed?

Most often the dimmer is an old leading-edge (TRIAC) unit made for halogen loads of 40 watts and up. LED downlights draw 6 to 12 watts each, below the dimmer's minimum load, so it chops the waveform unevenly and the LED driver shows it as flicker. A trailing-edge dimmer rated for LED, or a dimmer from the same maker as the downlight, cures it.

Can I replace a dimmer switch myself?

Not in Australia. A dimmer is hard-wired to the lighting circuit, and that work must be done by a licensed electrician. Cosmo can tell you which dimmer suits your downlights; your electrician fits it.

Why does one downlight flicker and the rest are fine?

One flickering fitting in a group usually points at that fitting: a driver on its way out, a loose plug between driver and light, or a globe that is not dimmable in a GU10 or MR16 fitting. Swap it with a neighbour; if the fault moves, it is the fitting.

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