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Lights flickering? Why it happens, and when to worry.
One light, every light, or only when the kettle goes on: what each pattern means and how to fix it.
Flickering lights are usually harmless and easy to fix, but sometimes they’re the first sign of a loose connection that’s overheating. Where the flicker happens tells you which.
One light flickering
- The bulb. Check it’s screwed or pushed in properly. Try a new bulb.
- An LED on a dimmer. Very common: see below.
- A loose connection in the light fitting or switch. If changing the bulb doesn’t fix it, or the switch is warm or crackles, call an electrician.
All the lights flickering
If lights flicker all over the house, ask a neighbour whether theirs are doing the same. If they are, it’s probably the electricity network: call 105, the free number for your local network operator. If it’s only your home, there may be a loose connection at the fuse board, the meter tails or the main earth. That needs an electrician promptly.
Lights dim or flicker when something switches on
A brief dip when a big appliance starts (a kettle, oven, electric shower or heat pump) can be normal. A noticeable dim every time, or one that’s getting worse, points to a poor connection or an overloaded circuit. We test the circuit and the supply to find out which.
LEDs and dimmer switches
Most flickering LEDs are on old dimmer switches designed for filament bulbs. Fixes:
- Use dimmable LED bulbs, and the same make and type in every fitting on the circuit.
- Fit an LED-compatible (trailing-edge) dimmer rated for the load.
- Check the dimmer’s minimum load: a few low-wattage LEDs may be below it.
Planning new lighting? See smart home and lighting control.
Questions we’re asked
Are flickering lights dangerous?
Often not: a loose bulb or an incompatible dimmer is the usual cause. But flickering with a warm or crackling switch, a burning smell, or flicker across the whole house can mean a loose connection that is overheating, which needs an electrician.
Why are my LED lights flickering?
Usually because they are on a dimmer designed for old filament bulbs, or the bulbs are not dimmable. A trailing-edge LED dimmer and matching dimmable bulbs normally fixes it.
Why do my lights flicker when the heating or kettle comes on?
A big appliance starting causes a small voltage dip. A slight flicker can be normal; a noticeable dim every time suggests a poor connection or an overloaded circuit.
All my lights are flickering. Who do I call?
Check with a neighbour first. If theirs are flickering too, call 105 for your network operator. If it is only your home, call an electrician.
Written by SEGplc. Last updated 19 October 2026.
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