How do I tell which switch has tripped on my switchboard?

On a modern board the devices sit in rows behind a hinged door. A tripped one stands out because its lever doesn't match its neighbours. Some brands drop the lever to a middle position rather than all the way off, and some have a small coloured window that changes when the device is off. Open the door only; never unscrew or lift off the panel behind it.

Check the main switch as well, because if it's off, everything is off. If every device is on and part of the house is still dead, the problem may be the supply or a sub-board somewhere else, such as in a garage, extension or granny flat.

Which device tripped tells you what kind of fault it was. Energy Safe Victoria says a safety switch always has a test button and 30mA printed on it. It trips when current leaks to earth, often from a faulty appliance or moisture, and it usually covers several circuits, so a whole group of rooms goes dark. A circuit breaker has no test button and trips for an overload or a short on its own circuit. An RCBO does both jobs for one circuit and has a test button too.

Before resetting, switch off or unplug what was running in the rooms that lost power. If the lever sits in the middle, push it fully down first, then up. If it stays on, plug things back in one at a time and watch for the trip. If it won't stay on, or trips again, leave it off. Energy Safe Victoria's advice is to call a licensed electrician if a safety switch won't reset.

Write down the label, the time, the weather and what was running. Labels on older boards are often missing or wrong, so the rooms that actually lost power tell us more than the label does. If your labels don't match what goes off, we can test and relabel the circuits.