Why Are My Lights Flickering?

Flickering has a wide range of causes. Some are a five-minute fix, one is serious, and the pattern usually tells you which you have.

One light, or all of them?

This is the question that splits the problem in half.

One fitting flickering points at that fitting: the lamp, the holder, or its connection.

Every light flickering points at something shared: the incoming supply, the main connections, or a neutral fault. That is the version to take seriously.

When it is one fitting

Start with the lamp itself. Loose in the holder is the commonest cause of all, so turn it off, let it cool, and reseat it. A worn holder that no longer grips is next, and cheap LED lamps flicker as their internal driver fails.

LEDs on an old dimmer are the single most frequent call we get about flickering. Dimmers made for filament bulbs expect a load of 40 watts or more. Put three 5 watt LEDs on one and the dimmer cannot regulate properly, so you get flicker, buzz and a limited range. A trailing-edge LED dimmer matched to the lamps fixes it.

Mixing brands in one fitting causes the same trouble. Different drivers behave differently on the same circuit.

When it is everything

If lights across the house dip together, note when it happens.

Dipping when a large appliance starts, such as a shower, oven or washing machine, is usually normal voltage drop, though pronounced dipping can mean an undersized supply or a poor connection worth investigating.

Flickering that has no pattern, affects the whole house, and has appeared recently is the one that matters. A loose neutral is the classic cause. The neutral is the return path for the whole installation, and when its connection loosens, voltage across your circuits becomes unstable. It can push voltage above normal on some circuits, which destroys electronics, and the loose joint heats as it arcs.

Call an electrician promptly for whole-house flickering that started recently, especially alongside any of these:

• Buzzing from the consumer unit
• Lights brightening as well as dimming
• A burning smell anywhere near the board
• A consumer unit or meter tails warm to the touch

Also worth knowing: if your neighbours have it too, the fault is on the network side. That is your distribution operator's responsibility rather than an electrician's, and they run a 24-hour number on 105.

What we check

For a single fitting, the lamp, the holder and its terminals. For a whole-house problem, voltage at the origin under load, the main tails and neutral connections, and a thermal check of the board for joints running hot.

The short version

One fitting flickering is usually the lamp, the holder or a dimmer mismatch, and it can wait. Everything flickering at once, especially if it is new, gets looked at this week.