Lighting faults: flickering, buzzing and lights not working

If one light flickers, try a new bulb. If it has a dimmer, check that the bulb says it is dimmable and that the dimmer is made for LEDs. Older dimmers were designed for filament bulbs and can make LEDs flicker or buzz.

If lights flicker across several rooms, a loose connection on the lighting circuit or the neutral is more likely. If the whole house flickers, and especially if your neighbours notice it too, the cause may be on the network side. Call 105 to report it. The London Fire Brigade lists flickering lights among the warning signs of loose or dangerous wiring.

A switch that buzzes or feels warm usually has a loose terminal or is a dimmer working too hard. A loose terminal makes heat, and heat damages the switch and the cable behind it. Stop using it and have it checked. See our advice on a light switch buzzing.

In Edwardian and Victorian houses, common in Ealing, Wandsworth and Hackney, light switches are often fixed into old metal boxes in plaster walls, with cable that has been extended over the years. These joints are a frequent source of trouble.

Water from a leak or overflowing bath often finds its way into ceiling lights, because the cable holes are the easiest path down. If water is coming through a light, do not touch the fitting or the switch. Switch off the main switch if you can reach it without standing in water, stop the leak if you can, and keep the lights off until the circuit has been tested. Our page on electrics after a leak or flood explains what happens next.

Most homes have one lighting circuit for each floor, sometimes more in bigger houses. If all the lights on one floor go out at once and the sockets still work, check the consumer unit for a breaker marked lights or a dropped RCD.

If it has tripped, switch off every light on that floor at the wall, reset the breaker, then switch the lights back on one at a time. If it trips when one light comes on, that fitting or its bulb is the likely cause. A bulb that blows can trip a breaker by itself, so try a new bulb first.

If nothing has tripped but the lights are still off, the circuit may be broken at a loose joint. That needs testing. Lighting circuits in older London houses often have junction boxes hidden under floorboards or above ceilings, added when rooms were knocked through or extended.

One extra check: lighting circuits wired before the 1960s, and some later ones, may have no earth conductor. Metal light fittings and metal switch plates should not be fitted on a circuit with no earth. An electrician can tell you whether yours has one. Our guide to rubber wiring in London homes explains the signs of very old circuits.