Short answer: A dimmer that buzzes, hums or makes LEDs flicker is usually a compatibility problem: the dimmer isn’t designed for the LED globes or drivers it’s controlling, or the load is below the dimmer’s minimum. Sometimes it’s a cheap or non-dimmable globe, a loose connection or a failing dimmer. A buzzing switch that’s hot, smells or crackles is a safety issue, so switch it off and call an electrician.
Dimmers were designed for old incandescent and halogen globes. LEDs work very differently, and many dimmer problems come from mixing old dimmers with new lights. Here’s how to work out what’s causing your buzz or flicker and what fixes it.
If you smell burning, see scorch marks or the dimmer is hot to touch, stop here. Turn off the light circuit at the switchboard and call an electrician. Our guide to a burning smell from a power point explains why heat is a warning sign.
Where is the noise coming from?
| Source | What it suggests |
|---|---|
| The dimmer on the wall | Dimmer not suited to the LED load, or near the end of its life |
| The light fitting or globe | Globe or driver not compatible with the dimmer, or not dimmable |
| The ceiling, near the fitting | LED driver (transformer) humming with the dimmer |
| Both, plus flicker | Classic incompatibility between dimmer and LED load |
The common causes
1. Non-dimmable LEDs
Not all LED globes are dimmable. A non-dimmable globe on a dimmer will often buzz, flicker or fail early. Check the packaging or the globe itself.
2. Wrong type of dimmer
There are different dimmer types, such as leading-edge and trailing-edge. Many LEDs work best with trailing-edge dimmers. An old leading-edge dimmer designed for incandescent globes can make LEDs buzz and flicker. Check the manufacturer’s compatibility list for your globes or downlights.
3. Load below the minimum
Dimmers have a minimum load. A dimmer designed for several 50 W halogens may not work properly with a few 8 W LEDs. The fix may be a dimmer with a lower minimum load, or a different dimmer type.
4. Mixed brands or drivers
Mixing LED brands, or different drivers, on one dimmer can cause uneven dimming and noise.
5. Low-quality LEDs
Cheap LEDs and drivers can hum or flicker on any dimmer. Quality fittings from a reputable supplier tend to dim more smoothly.
6. Loose connections or a failing dimmer
A worn dimmer or a loose terminal can buzz and heat up. This is the case where safety matters most.
What you can safely try
- Check the globes are dimmable. Swap a non-dimmable globe for a dimmable one.
- Turn the dimmer to full. If the buzz stops at full brightness, it’s likely compatibility rather than a fault.
- Try one brand of globe across the whole circuit.
- Note when it happens: at low settings, all the time, or only when warm.
Anything that involves removing the dimmer from the wall is electrical work for a licensed electrician.
What an electrician will do
- check the dimmer type and rating against the LED drivers
- check the minimum and maximum load
- tighten or replace connections
- replace the dimmer with a compatible model, often trailing-edge or universal
- recommend matched LED fittings if the existing ones are poor quality
Our LED downlight buying guide explains how to choose fittings that dim well.
Flicker without a dimmer?
If lights flicker on a normal switch, the cause may be the globe, a loose connection or something on the supply. See why are my lights flickering?.
Smart dimmers
Smart dimmers have the same compatibility issues, plus some need a neutral at the switch. Check compatibility before buying. See smart home wiring.
Dimmer buzzing or lights flickering? We replace dimmers and match them to your LEDs so they dim smoothly and quietly. See our LED lighting in Petersham or call 0421 772 661.
Planning new dimmable lighting
If you’re installing pendants, downlights or feature lights, choose the dimmer and fittings together. Ask your electrician which combination is tested and compatible.
We fix dimmer and lighting problems in Dulwich Hill, Leichhardt, Stanmore and nearby suburbs. See our indoor lighting service for more.
Frequently asked questions
Why does my dimmer switch buzz with LED lights?
Usually because the dimmer isn’t compatible with the LED globes or drivers, the LEDs aren’t dimmable, or the load is below the dimmer’s minimum.
Is a buzzing dimmer dangerous?
A slight hum from incompatibility isn’t usually dangerous, but a dimmer that’s hot, crackles or smells of burning is. Switch it off and call an electrician.
Can I change a dimmer switch myself?
No. Replacing a wall dimmer is electrical work and needs a licensed electrician in NSW.
What dimmer works best with LEDs?
Many LEDs work best with trailing-edge or universal dimmers. Check the LED manufacturer’s compatibility list.