Flickering lights range from completely harmless to a genuine warning sign. The key is telling them apart. This guide runs through the causes from least to most serious, so you know whether to swap a bulb or pick up the phone.

Start simple: the bulb and fitting

Most flickering is mundane:

• LED bulb incompatible with the dimmer. The most common cause today — many older dimmers weren’t designed for LEDs and cause flicker. Fitting LED-compatible (trailing-edge) dimmers usually fixes it.
• A loose or failing bulb. Make sure it’s screwed/seated properly; try a new bulb.
• End-of-life bulb. Flickering then failing is normal for a dying bulb.

If only one fitting flickers and a new, compatible bulb fixes it, you’re done.

Worth attention: loose connections

If flickering persists or affects a whole circuit, the cause is often a loose connection — at the light fitting, switch, or in the wiring. Loose connections cause arcing, which is both a flicker source and a fire risk. This isn’t a DIY fix: it needs an electrician to find and tighten or remake the connection safely.

A sign of overload

Lights that dim or flicker when a big appliance kicks in — the shower, kettle, washing machine, or when the fridge compressor starts — suggest the circuit or supply is being heavily loaded. Occasional slight dimming can be normal; persistent, noticeable dimming is worth investigating, as it can indicate an overloaded circuit or an undersized supply.

When it’s the whole house

If all your lights flicker, or it happens across multiple circuits:

• It could be a loose connection at the consumer unit or main supply — potentially serious.
• It could be a supply issue from the network (sometimes a neighbourhood problem). If neighbours have it too, report it to your DNO (distribution network operator).
• A failing main connection can cause whole-house flicker and is a genuine hazard.

Whole-house flickering that isn’t a known supply issue should be checked promptly.

The warning signs that mean call now

Treat flickering as urgent if it comes with:

• A burning smell or scorch marks near switches, sockets, or the board
• Buzzing or crackling from fittings or the consumer unit
• Fittings or switches warm to the touch
• Flickering that started suddenly across the whole house

Any of these — switch off the affected circuit if you safely can and call an electrician; see our emergency electrician service.

How an electrician diagnoses it

Beyond the obvious bulb/dimmer checks, an electrician will look for loose terminations, test the circuit, check the consumer-unit connections, and measure whether the supply voltage is stable. If flickering is down to old, deteriorating wiring or connections, it may point to the need for remedial work or, in older homes, a rewire — our signs your house needs rewiring guide covers that.

Quick self-check before you call

1. Does a new, compatible bulb fix it? (bulb/fitting issue)
2. Is it only on a dimmer? (try an LED-compatible dimmer)
3. Does it happen when a big appliance starts? (possible overload)
4. Is it whole-house or with a smell/buzz? (call an electrician — possibly urgent)

Get flickering checked

If it’s more than a bulb — a whole circuit, the whole house, or any smell or buzzing — GFL Electrical can find and fix the cause safely. NICEIC-approved, covering East London. Call 020 3774 5604 or get in touch.