Where the hum is coming from
Stand under the light, then beside the switch. A hum from the wall plate usually points to the dimmer. Older dimmers were made for filament globes and cut the power in a way many LED drivers don't like, so the dimmer, the driver or both vibrate and sing. It often gets louder at lower settings.
A hum from the ceiling points to the fitting. Many homes that moved from halogen to LED kept the old transformers and simply changed the globes. Those transformers were built for a much bigger load, and with a small LED globe on them they can buzz, flicker or cut out. Cheap globes and downlights with low-grade drivers can also whine on their own, even on a plain switch.
Mixed fittings and too few lights on a dimmer
A dimmer needs a certain minimum load to work smoothly. Put three or four efficient LEDs on a dimmer designed for a room full of halogens and it may never settle. Mixing two or three makes of downlight on the same dimmer causes similar trouble, because each driver reacts differently. The usual fix is a dimmer matched to the drivers, one fitting range per circuit, and the old transformers taken out.
When buzzing is a sign of a fault
A steady, faint hum is mostly a nuisance. A crackle or sizzle, a buzz that comes and goes with flicker, a switch plate that feels warm, a fishy or burning smell, or brown marks around a fitting can mean a loose or overheating connection. That is a fire risk rather than a noise problem.
Changing a dimmer, switch or fitting is electrical work. Energy Safe Victoria says it isn't a DIY job, even for small jobs like changing light switches. When we fix it, we check the driver and dimmer pairing, remove any leftover transformers and issue a Certificate of Electrical Safety for the work.
What you can safely do now
- Turn the light off at the wall if the buzz comes with crackling, flicker, heat or a smell, and leave it off.
- Try the dimmer at full brightness. If the hum stops, the dimmer and the LED drivers are probably a poor match.
- Note which room, which lights and which globes or fittings are involved, and keep any product boxes.
- If a fitting or switch is scorched or smoking, switch that circuit off at the switchboard if it is safe to reach.
Services that can help
Read more in our guides
Related questions
- Why does my light switch buzz or feel warm?A dimmer can hum faintly and feel a little warm, because it is an electronic device that sheds some heat while it works.
- Why do my lights turn on or off by themselves?Lights that switch on or off by themselves are usually following instructions you've forgotten: a smart switch schedule, a routine in an app, a motion or daylight…
- Why do my light globes keep blowing?Globes that fail early usually have help.
- Why has the ceiling around my light gone brown?A brown ring hugging the edge of a light is usually heat or dust.
Sources for this answer
2 sources, with the date each was checked
- 1.Energy Safe Victoria: Electrical work isn’t a DIY job, even for small jobs such as changing power points or light switches. Accessed 30 September 2026.
- 2.Energy Safe Victoria: Whenever a licensed electrician completes any electrical installation work, they must provide a Certificate of Electrical Safety (COES). Accessed 30 September 2026.
General information for homes in Victoria. Every installation is different, so treat this as a starting point. Where this answer refers to Victorian safety or rental rules, the sources above have the current requirements.