Why are my lights flickering?

Glossary · Wiring, circuits and faults

What causes flickering lights

The cause is either in the bulb or in the wiring. A bulb near the end of its life, or one that is not seated properly, can flicker on its own. NICEIC says that if your lights flicker on the odd occasion you may just need to change the bulb. If the lights constantly flicker, or the bulb is always burning out, it may point to a bigger problem.^{[2]NICEIC, Rewiring your house: an essential guide for homeowners}

Electrical Safety First goes further on the wiring side. Lights that keep blowing or flickering can indicate a loose connection rather than a faulty bulb.^{[3]Electrical Safety First, Haunted or Just Hazadous? Residents in Uk's Spookiest Cities Urged to Call an Electrician, Not a Ghostbuster This Halloween} Its advice for the living room is that flickering lights should not be ignored, because they can be a sign that the installation needs to be inspected by a registered, competent electrician.^{[1]Electrical Safety First, Electrical Safety Advice for Living Rooms}

A loose connection matters because it can heat up. NICEIC lists flickering lights, buzzing sounds, discoloured switches or sockets and hot plugs among the signs that a home may need rewiring, and says that if you notice them you should contact an electrician immediately.^{[2]NICEIC, Rewiring your house: an essential guide for homeowners} Our guide to full and partial rewires explains when a rewire is the answer and when a repair is enough.

What you can check yourself

The checks that are safe for a householder are the ones that do not involve opening anything.

• Note whether it is one light or several. One fitting suggests the bulb or that fitting. Several lights on the same lighting circuit point further back.
• Note when it happens, for example only when a large appliance switches on, or all the time.
• Look for company: a burning smell, buzzing or crackling, a hot or discoloured socket or switch.
• Write the details down so the electrician can see the pattern.

On that third point, Electrical Safety First says not to ignore burn marks, arcing sounds (buzzing or crackling), fuses blowing, circuit-breakers tripping or anything hot to the touch, and to unplug and contact the retailer, manufacturer or a qualified repair technician.^{[4]Electrical Safety First, Electrical Safety Advice for Earthing and Bonding}

Do not open light fittings, switches or the consumer unit to look for the fault. Electrical Safety First advises contacting a competent registered electrician to investigate suspected electrical faults such as flickering lights.^{[1]Electrical Safety First, Electrical Safety Advice for Living Rooms}

When to call an engineer

Call an electrician if the flicker is constant, if bulbs keep blowing, or if it comes with any warning sign above. Electrical Safety First also says tripping electrics can mean circuits are overloaded or the wiring is deteriorating, so flickering together with tripping is worth reporting in the same visit.^{[3]Electrical Safety First, Haunted or Just Hazadous? Residents in Uk's Spookiest Cities Urged to Call an Electrician, Not a Ghostbuster This Halloween} See why an RCD keeps tripping for that side.

If the home is rented, report it to the landlord. Electrical Safety First says unpleasant smells such as burning plastic should be reported immediately to the landlord.^{[3]Electrical Safety First, Haunted or Just Hazadous? Residents in Uk's Spookiest Cities Urged to Call an Electrician, Not a Ghostbuster This Halloween} For an installation that has not been tested for years, an Electrical Installation Condition Report shows the state of the wiring, and our guide to what an EICR tests explains the checks.

Example

Carl in Armley notices the hallway light dimming every few minutes. He changes the bulb and the flicker continues. The pendant also feels warm when he turns it off. He leaves it switched off, tells a registered electrician about the heat and the history and books a visit. The electrician finds and repairs the cause and tests the circuit before leaving. Carl did only what was safe: he swapped a bulb, noticed the warmth and made the call.

What people get wrong

Many people put flickering down to the bulb, change it three times and carry on. NICEIC says a bulb that keeps burning out suggests a bigger problem. A fault that keeps destroying bulbs is a fault in the circuit, and bulbs are the cheap part.

The opposite mistake is assuming flickering always means the wiring is failing. Occasional flicker on one bulb can be the bulb. The skill is noticing when it is not.

The bottom line

Flickering lights are sometimes a failing bulb and sometimes a loose connection or deteriorating wiring. Change the bulb once, and if the flicker stays, or bulbs keep blowing, stop guessing. Electrical Safety First says flickering should be investigated by a registered, competent electrician, and a burning smell, buzzing or heat makes it urgent.