Why can I hear crackling in my walls or ceiling?

Roof timbers and metal roofing tick and crack as they heat up on a summer afternoon and cool in the evening. Hot water pipes tick as they warm after a shower or while the dishwasher runs, and heating and cooling ducts can pop as warm air comes through. Scratching, scurrying or thumping at night, often near the eaves, is more likely rats, mice or possums.

These noises follow the weather, the time of day or the plumbing. They don't change when you switch lights or appliances on and off.

Arcing sounds like a crackle, sizzle or fizz rather than a tick, and it comes from where wiring connects: behind a switch or power point, at a light fitting or downlight, or at the switchboard. It often changes when a particular light or appliance is switched on, and may come with flickering, a warm or discoloured plate, a burning or fishy smell, or a breaker tripping. Energy Safe Victoria lists flickering lights and sparks from switches, power points or switchboards among the warning signs of faulty wiring.

Rats and mice also chew cable insulation in roof spaces, so animal noises followed by a new electrical fault deserve a proper check.

If a sound might be electrical, switch off the lights and appliances near it. If it carries on, switch circuits off one at a time at the switchboard, through the open door and without removing any covers, and listen for whether it stops. If turning off one circuit stops it, leave that circuit off and book a check. Don't open walls, pull down light fittings or go into the roof space to hunt for the source.

We test the circuit, open up the fittings on it and look for heat damage at the connections, so you know whether the noise was electrical and what was causing it.