Lights flickering in the house: bulb, dimmer or wiring?

Most flickering lights are not an emergency. A tired bulb or a dimmer switch that does not like LEDs causes more flicker than anything else. But flicker can also be the first sign of a loose connection, and loose connections create heat. The job is to work out which one you have.

If you would rather have someone test it, our lighting and circuit faults page explains how a visit works.

Start with the pattern

Where and when the flicker happens tells you a lot.

Pattern	Most likely cause	What to do
One light only, others fine	Bulb, bulb holder, or LED not suited to the dimmer	Swap the bulb for a known good one
Only on a dimmed light	LED and dimmer mismatch	Fit a dimmer made for LEDs, or use non dimmable bulbs on a plain switch
Several lights on one circuit	Loose connection on that lighting circuit	Get it tested
Lights dip when a big appliance starts	Loose connection, or a long and undersized circuit	Get it tested, sooner if it is getting worse
Every light in the home flickers at once	Loose connection at the main switch, meter tails or supply	Call 105 if neighbours see it too; otherwise call an electrician
Flicker with buzzing, warmth or burning smell	Overheating connection	Switch off that circuit and call now

Step one: rule out the bulb

Turn the light off at the switch and let the bulb cool. Swap it for a bulb you know works in another fitting. If the flicker stops, you are done.

With LEDs, also check the box. Many LED bulbs are not designed for dimmers. Put one on an older dimmer switch and it may flicker, buzz or glow faintly when off.

Step two: think about the dimmer

Older dimmer switches were designed for filament bulbs that drew a lot of power. A room of LEDs may draw so little that the dimmer cannot control it smoothly. The result is flicker at low settings.

The fix is usually a dimmer made for LED loads, or LED bulbs that list your dimmer type as compatible. If the dimmer itself is warm or buzzing, see our guide to a light switch buzzing or warm.

Step three: look at the whole house

If more than one light is flickering, the bulb is not the problem. Check:

• Is it all the lights on one floor? Lighting circuits are often split upstairs and downstairs.
• Does it happen when the oven, shower, kettle or heater switches on?
• Are your neighbours seeing the same thing?

If the whole street is affected, it is a network issue. Call 105, or check the UK Power Networks power cut page. They also take calls on 0800 31 63 105.

If it is only your home, the cause is somewhere between the meter and your light fittings. Do not open the consumer unit or any fittings to look. A loose neutral connection in particular can cause odd voltage on other circuits, and that is a job for testing equipment.

Why loose connections matter

A loose screw terminal does not just interrupt the power. It creates a small gap where electricity arcs across. That arcing gives off heat and slowly damages the cable and the fitting. Flicker is often the visible sign.

London Fire Brigade lists flickering lights among the signs of loose or dangerous wiring, alongside scorch marks, hot plugs and sockets, and breakers that trip for no obvious reason. LFB says it has attended 26,376 electrical fires in London since 2017.

Enfield homes and flicker

Enfield is a good example of where flicker tends to come from. The VOA’s housing stock figures show that 37% of homes in Enfield are terraced houses, the highest share of the areas we cover, and 23% were built before 1919. Another 35% were built between 1919 and 1939.

Those Victorian and Edwardian terraces in Edmonton, Bush Hill Park, Palmers Green and Winchmore Hill have usually been rewired at some point. The question is when. A rewire done several decades ago may have ceiling roses (the round fitting where a pendant hangs) and junction boxes under the floor with terminals that have worked loose over time. Loft conversions and kitchen extensions often added new lights onto the old circuit rather than a new one.

If you live in an older terrace in Enfield and the flicker affects more than one room, ask for the lighting circuit to be tested, not just the fitting swapped.

What an electrician will test

A lighting fault visit usually goes like this:

1. Ask when the flicker happens and which lights are affected.
2. Check bulb and dimmer types.
3. Measure the voltage at the fitting while loads are switched on and off.
4. Test the circuit’s connections and insulation from the consumer unit.
5. Open and check the ceiling roses, switches and junction boxes on the circuit, making good any loose or scorched terminals.
6. Check the main connections at the consumer unit and the meter tails (the thick cables from the meter to the consumer unit).

If the meter tails or the main fuse look like the problem, the electrician will tell you. The main fuse (the cutout) belongs to the network operator, and the meter belongs to your supplier.

When to stop using the light

Switch off the lighting circuit at the consumer unit, and call for help, if:

• The fitting or switch is warm to touch
• You can smell burning or hot plastic
• You see scorch marks on the ceiling or around the switch
• The light is near a leak or a damp patch
• The flicker started after water came through the ceiling. See our guide to water leaking through a light fitting.

Getting it looked at

Most flicker is cheap and easy to fix once the cause is found. The hard part is finding it. If you have ruled out the bulb and dimmer and it is still happening, request a visit through our lighting faults service. The price is confirmed after a look at the job.