First, which thing is tripping?

Open the switchboard and look at what has gone to the off position.

  • A single circuit breaker (labelled Lights, Power, Oven and so on): overload or fault on that circuit.
  • A safety switch (RCD, usually with a test button): earth leakage somewhere on the circuits it protects. This is the most common one.
  • The main switch: a fault upstream of the circuits, or the supply is overloaded. Do not keep resetting this.

The seven causes

  1. A faulty appliance. Kettles, toasters, old fridges, heaters and anything with a heating element are the usual suspects. Unplug everything on the tripping circuit, reset, then plug things back one by one. When it trips, you have found it.
  2. Overload. Too much on one circuit at once. A heater, a hair dryer and a microwave on the same power circuit will do it. Spread the load or add a circuit.
  3. Moisture. After rain, an outdoor power point, garden light or pool pump with water in it will trip the RCD. Very common on the Coast in winter. Dries out and stops, then does it again next storm.
  4. A failing safety switch. RCDs wear out. If it trips with nothing plugged in and no pattern, it may be the device itself. Cheap to replace.
  5. A wiring fault. Rodent damage, a nail through a cable during a reno, or perished insulation in an older home. Needs fault-finding.
  6. A loose connection. Heats up, arcs, trips. Can show as a burning smell or a warm switchboard. Treat as urgent.
  7. Undersized supply. The house has grown (air-con, EV, pool) and the consumer mains or main switch cannot cope. Trips tend to happen at peak times, evenings in summer. The fix is a mains upgrade, which is Level 2 work.

When to stop and call

  • The main switch trips
  • Any burning smell or discolouration at the board
  • Tripping with nothing plugged in
  • The board has ceramic fuses or no safety switches at all
  • Tripping started after storm damage or a nearby tree fall

Old switchboards

A lot of Central Coast homes from the 60s to the 80s still have the original board. No RCDs, rewirable fuses, and no room to add anything. If yours looks like that, tripping is the least of the problems. A modern board with RCBOs on every circuit is from about $1,800 and turns "why does it keep tripping" into a labelled breaker that tells you. See switchboard upgrades and safety switches.