Flickering lights are one of the most common electrical complaints in UK homes. Sometimes the cause is trivial. Sometimes it indicates a serious fault. This guide helps you work out which.

Simple causes (check these first)

Loose or failing bulb

The most common cause of a single flickering light is a loose bulb or a bulb that is reaching the end of its life. LED bulbs can flicker when their driver circuit starts to fail.

What to try: Turn off the light, let the bulb cool, and reseat it firmly. If it still flickers, try a replacement bulb.

Incompatible dimmer switch

If your lights flicker on a dimmer, the dimmer may not be compatible with the bulbs. This is extremely common when halogen bulbs have been replaced with LEDs without upgrading the dimmer switch.

Standard leading-edge dimmers (designed for halogen) often cause LED bulbs to flicker, buzz, or not dim smoothly. A trailing-edge dimmer designed for LED loads resolves this.

What to try: If the flickering only happens on a dimmed circuit, the dimmer is likely the issue. Replacing it with an LED-compatible dimmer is a straightforward job.

Loose connection at the light fitting

A loose wire at the ceiling rose or light fitting can cause intermittent flickering, particularly if the light flickers when the fitting is touched or when there is vibration (such as someone walking on the floor above).

What to do: This requires the power to be switched off at the consumer unit and the fitting to be inspected. If you are not comfortable doing this, call an electrician.

More serious causes

Loose connection in the circuit

A loose connection at a junction box, switch, or socket on the lighting circuit can cause flickering. These loose connections generate heat and can be a fire risk if left unaddressed.

Signs that the cause is a loose connection:

Multiple lights on the same circuit flicker
The flickering is intermittent and unpredictable
You notice a warm or discoloured switch or socket on the same circuit

This needs an electrician to inspect and tighten or replace the affected connection.

Overloaded circuit

If your lights dim or flicker when a high-power appliance kicks in (such as a washing machine, electric shower, or kettle), the lighting circuit may be sharing a supply with the appliance circuit, or the incoming supply may be undersized for the total load.

Occasional brief dimming when a large appliance starts is relatively normal. Persistent or severe dimming is not.

Deteriorating wiring

In older properties, the insulation on lighting cables can degrade over time. This causes intermittent contact between conductors or between a conductor and earth, resulting in flickering or tripping.

If your home was built before 1970 and the lighting circuit has not been rewired, deteriorating cables are a realistic possibility.

Incoming supply problem

If every light in the house flickers simultaneously, the problem may not be inside your home. It could be:

A loose connection at the meter or cutout
A fault on the electricity distributor’s supply
Work being carried out on the local network

What to do: Check with your neighbours. If they are experiencing the same issue, contact your electricity distributor (the company that owns the cables and meter, not your energy supplier). If the issue is only in your home, contact an electrician.

Neutral fault

A loose or damaged neutral connection can cause voltage fluctuations that make lights flicker, brighten, or dim unpredictably. This is a serious fault that can damage appliances and is a fire risk. If your lights are noticeably brighter than normal, or if you see voltage fluctuations across different circuits, switch off at the main switch and call an electrician immediately.

When to call an electrician

Call an electrician if:

Multiple lights flicker on the same circuit
Flickering is accompanied by a buzzing or humming sound
You see discolouration or feel warmth at a switch or socket
Lights flicker persistently after replacing the bulb
All lights in the house flicker simultaneously
Lights are noticeably brighter or dimmer than usual

Next steps

If you are experiencing persistent flickering that is not resolved by changing a bulb or replacing a dimmer switch, contact us for a fault finding appointment. We will test the affected circuit, locate the cause, and carry out the repair.

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Lights Flickering in Your House? Here's Why