Buzzing, heat or a burning smell? Turn it off
Switch the light off and leave it off. If a switch or fitting feels hot, smells of hot plastic or crackles, turn off that circuit at the switchboard if you can do it safely, and call an electrician. If there's smoke or fire, get out and call 111. Burn marks, a strange smell or crackling at the switchboard itself mean don't touch it and contact your lines company straight away, which is ENA's advice.
What the pattern usually means
| Most likely cause | Who sorts it | |
|---|---|---|
| One bulb flickers | A bulb near the end of its life, or one that isn't seated properly | Try a new bulb, with the light off and cool |
| LEDs flicker on a dimmer | A dimmer that doesn't suit the LED bulbs or driver | An electrician, to fit a compatible dimmer |
| Lights dip when the oven, heater or dryer starts | A heavy load on a shared circuit, or a loose connection | An electrician |
| One room flickers on and off | A loose connection at a switch, fitting or junction | An electrician, soon |
| Every light in the house brightens and dims | The supply, or a loose main connection | Your lines company first, then an electrician |
| The neighbours' lights flicker too | The lines company's network | Your lines company |
Why LEDs flicker more than old bulbs did
LED bulbs and downlights run on electronics, and those electronics are fussier about the power they get. Many older dimmers were designed for incandescent bulbs, and at low settings they can make LEDs shimmer, pulse or hum.
Mixing brands on one dimmer can cause the same thing. So can a cheap LED that's simply failing. If the flicker only happens when the dimmer is turned down, the fix is usually a dimmer made for LEDs rather than anything in the wiring.
When it's the supply, not your house
If lights all over the house are brightening and dimming, and especially if the neighbours notice the same, the problem may be on the lines company's side. Network Tasman, for example, asks people whose power is fluctuating, with lights dimming and brightening, to ring its 24 hour fault line on 0800 508 100.
Not sure who your lines company is? The ENA map at ena.org.nz lets you enter your address and shows its name, phone number and website. If you live near a boundary, ENA suggests checking with the companies on both sides.
If the lines company finds nothing on its side, the next suspect is a loose connection at your main switch or meter board, and that's a job for an electrician.
Narrow it down before you call
Note which lights, and when
One fitting, one room or everywhere? All the time, only on the dimmer, or only when something big switches on?
Try a new bulb in the one fitting
With the light switched off and the bulb cool. If the flicker moves with the old bulb, the bulb was the problem.
Watch what happens when big appliances start
A brief dip as the oven or heater kicks in can be normal. A long dip, or a flicker that keeps going, is worth mentioning to an electrician.
Ask a neighbour
If they're seeing it too, contact your lines company rather than an electrician.
Leave anything warm or buzzing off
Don't keep testing a fitting that's hot or noisy. That's the one an electrician needs to see.
What the electrician checks
They'll start where the pattern points. For one fitting, that's the fitting, the switch and the connections behind them. For a room, it's the circuit and any junctions along it. For the whole house, it's the main connections at the board and whether the supply voltage is steady.
Loose connections get hot, which is why a flicker sometimes comes with a smell or a warm faceplate. If the electrician suspects a hidden hot spot, a thermal imaging check can show it without opening walls. Replacing a faulty switch or fitting is low-risk work and comes with an Electrical Safety Certificate.
What you can do, and what's licensed work
You can
- Change a bulb, with the light switched off and cool.
- Note the pattern: which lights, when, and what else was running.
- Ask the neighbours, and call your lines company if the whole street is affected.
- Turn off and leave off anything that's hot, buzzing or smells.
Leave to a licensed electrician
- Changing dimmers, switches and light fittings when there's a fault. The homeowner exemption for owner-occupiers doesn't make a flicker a DIY job.
- Tracing a loose connection in a switch, fitting, junction or the ceiling.
- Anything at the switchboard or main switch.
- Checking whether a circuit is overloaded.
Our rule of thumb
One flickering bulb, we'd swap the bulb. Flicker on a dimmer, we'd get the dimmer changed for one that suits LEDs. Anything that moves between rooms, comes with a noise or a smell, or affects the whole house, we'd treat as a fault and get an electrician who does fault finding to trace it. A flicker isn't an emergency, but it's rarely something that fixes itself.
Want a specialist to sort it?
Tell us the job and your postcode. We match the licence-checked local electrician who does this kind of work, and they call you. No ring-around, and your number goes to them alone.