Why does my lighting circuit keep tripping?

The most common causes are a faulty light fitting, a loose connection at a ceiling rose or junction box, or a failed LED driver. If you recently changed bulbs or fittings, that is the likely culprit.

Can the wrong type of LED bulb cause tripping?

Yes. Incompatible LED bulbs, especially in dimmer circuits, can cause issues. Some LED bulbs have a high inrush current on startup that can trip a 6A MCB. Use LED bulbs specified as compatible with your fittings.

Are recessed downlights a common cause?

Yes. Recessed downlights can overheat if covered by loft insulation or if the wrong type is fitted without fire hoods. They are also prone to condensation issues. Modern fire-rated LED downlights are much better in this regard.

Is it safe to change a light fitting myself?

Simple like-for-like replacements are generally acceptable if you isolate the circuit at the consumer unit first. However, any changes to the circuit itself, adding new lights, or working on bathroom fittings should be done by a qualified electrician.

Could a dimmer switch be causing the problem?

Yes. Old dimmer switches designed for halogen bulbs often do not work well with LED bulbs. If your lights flicker or the circuit trips when dimmed, you may need an LED-compatible dimmer switch.

Caution

Updated 30 August 2026

Lighting Circuit Keeps Tripping

Your lighting circuit keeps tripping, plunging rooms into darkness.

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What's happening?

A dedicated lighting circuit MCB (typically rated at 6A) keeps tripping, turning off all the lights on that circuit. UK homes usually have one or two lighting circuits, so the trip may affect lights throughout the house or on one floor. Lighting circuit faults are often related to light fittings, switches, or wiring in the loft and ceiling voids.

What usually causes it?

Faulty light fitting with a short circuit or earth fault
Incorrect bulb type or wattage causing overheating in a fitting
Loose connection at a ceiling rose, junction box, or light switch
LED downlight driver failure causing a short circuit
Water ingress into a ceiling light from a leak above
Damaged cable in the loft, especially if disturbed during loft boarding or insulation work

Is it dangerous?

A tripping lighting circuit is not an immediate danger, but it does leave you in the dark, which creates trip and fall hazards, especially on stairs. The underlying fault — particularly loose connections in ceiling roses — can cause arcing and overheating, which is a fire risk. Do not ignore persistent tripping.

Can I fix it myself?

Switch off all the light switches in the house (or on the affected floor) and reset the MCB. Turn lights on one at a time. If a particular light causes the trip, the fitting or its connections are faulty. Check if you recently changed any bulbs — incompatible LED bulbs or wrong-wattage bulbs can cause problems. Do not remove or open light fittings unless you have isolated the circuit.

When should you call an electrician?

Call an electrician if you cannot identify which light is causing the trip, if the circuit trips with all lights off (suggesting a wiring fault), if you have recessed downlights that may have overheated, or if there are any signs of water near a light fitting. Lighting circuit work should be carried out by a qualified electrician.

What will the electrician actually do?

Test the lighting circuit for short circuits and earth faults
Inspect each light fitting, ceiling rose, and junction box for loose connections
Check LED drivers and transformers for faults
Inspect loft wiring for physical damage or disturbed connections
Replace faulty fittings, drivers, or connections
Test the circuit after repair and verify all lights operate correctly