Why your lights are flickering

First, work out how much of the house is flickering

Most flickering turns out to be a dimmer that does not suit the LED globes wired to it, and that one is an annoyance rather than a danger. The version to take seriously is flickering that hits the whole house at once. That points at a loose connection carrying real current, or a problem on the supply side. Both of those make heat.

Before you ring anyone, spend two minutes working out the pattern:

• One fitting only. Note whether it flickers on every dimmer setting or only low down, and whether it settles once it warms up. Try a different globe if you can reach it safely.
• One room or one run of lights. That usually means one circuit, and usually one connection somewhere along it.
• The whole house at once. Watch what else is happening. If it dips when the air conditioner, pool pump or bore pump starts, that is a voltage dip. If it flickers at random with nothing running, treat it as urgent.
• Look outside at night. If the neighbours' lights and the street lights are doing it too, the problem is on the network, not in your house.
• Stand near the switchboard. Do not open it. If the cover feels warm, or you hear buzzing or crackling, or you smell hot plastic, turn off the main switch and get an electrician out.

What it usually turns out to be

By a long way the most common cause is a dimmer and LED mismatch. Old dimmers were built for the load of a filament globe. A couple of LED globes drawing a few watts is not enough to keep them stable. You get flicker at low settings, a faint hum, or globes that will not go fully off. The fix is a dimmer designed for LED loads, matched to the globes. Sometimes the globes need changing too, because cheap ones will flicker on anything.

Next is a loose connection, either at the fitting, at a switch, or on a terminal in the switchboard. A loose terminal arcs, arcing makes heat, and heat makes the connection worse. This is the one that starts fires, and it is why flickering across several circuits gets a same day response from us rather than a booking next week.

Third is voltage dip from a big load starting. A pool pump, bore pump or air conditioning compressor pulls a large surge for a fraction of a second. A brief dim as it kicks in can be normal. A deep dip, or one that keeps going after the motor is running, usually means the circuit feeding it is undersized, the motor is drawing more than it should, or the switchboard is tired.

Up this way there are a couple of local causes worth naming. Ants and geckos nesting in outdoor fittings and enclosures is a common fault we find, particularly in the wet season. So is salt air corrosion on terminals anywhere near the coast between Craiglie and Port Douglas. After a storm, damaged overhead services and water in fittings cause flicker that will not fix itself.

What not to do

Do not keep using a dimmer or a fitting that buzzes, gets hot, or smells like hot plastic. Do not pull a light fitting down to have a look, because the wiring above a ceiling rose is live even with the switch off. Do not swap a dimmer yourself. Under Queensland law, testing and locating faults on live equipment is energised electrical work and is not a homeowner job. And do not ignore a whole house flicker because it is intermittent. Intermittent is exactly how a failing connection behaves right up until it fails properly.

What we do when we get there

We start by confirming the pattern, then measure. Voltage at the board and at the affected point, voltage drop under load, and a check of switchboard terminations for heat and discolouration. From there it is either a dimmer and globe match sorted on the spot, a connection remade and torqued properly, or proper fault finding across the circuit if it is hiding. If the flicker is on the network side we confirm it with readings and tell you what to report. Where the board itself is the weak point, we will explain what a switchboard upgrade would involve before you commit to anything.

Sources: WorkSafe Queensland, testing and energised electrical work; Electrical Safety Queensland, electrical safety during storms.