Why Does My Electric Keep Tripping?

You go to boil the kettle and the power goes off. You reset the switch, and an hour later it happens again. A circuit that keeps tripping is frustrating, but it's also the consumer unit (the fuse box) telling you something is wrong. Here's what is usually behind it.

RCD or circuit breaker?

First, look at which switch has gone off. An RCD (often marked RCD or with a "T" test button) protects against current leaking to earth, which could otherwise give someone a shock. A circuit breaker (MCB) protects one circuit against too much current. An RCBO does both for a single circuit. The type that trips gives a clue to the cause.

Common causes

A faulty appliance

By far the most frequent cause. Anything with a heating element (kettles, toasters, ovens, washing machines, dishwashers, immersion heaters) can develop a small leakage as the element ages. Often the trip happens when that appliance switches on, or partway through a cycle.

Moisture

Water and electricity don't mix, and even a little damp lets current leak. A bathroom extractor fan, a light fitting below a leaking shower, or an external wall that gets soaked can all cause trips, often only after rain or a shower.

Outdoor circuits

Garden sockets, outside lights, pond pumps and cables to sheds and garden rooms are exposed to the weather. Seals perish, cables get nicked by spades, and fittings fill with condensation. If your trips come with wet weather, start your suspicions here.

A damaged cable

A nail or screw through a cable when hanging a picture or fitting shelves, a rodent chewing cables in the loft, or old insulation breaking down can all create a path for current to leak. These faults usually trip whether or not anything is plugged in.

An overloaded circuit

If a circuit breaker (rather than an RCD) trips, the circuit may simply be carrying too much: a heater, a tumble dryer and a kettle on the same sockets, for instance. Spread the load. If it keeps happening, you may need more circuits.

The safe isolate-and-test steps

These are the only checks we suggest a homeowner tries:

1. Check the consumer unit labels to see which switch has tripped and which circuit or group of circuits it covers.
2. Unplug every appliance on the affected circuits, or switch them off at the wall, including fixed items like the immersion heater and outside lights if they have their own switch.
3. Reset the switch. If it stays on, the fixed wiring may be fine.
4. Reconnect appliances one at a time, waiting a little between each. If it trips when a particular one goes back in, leave that appliance unplugged and have it checked or replaced.
5. Test the RCD with its test button once it's holding. It should click off, then switch it back on.

When to call an electrician

• It trips with everything unplugged, or won't reset at all.
• It trips at random and you can't link it to any appliance.
• There's a burning smell, scorching, buzzing or a hot socket. Switch off if safe and call straight away.
• It happens in wet weather and you suspect an outdoor circuit.

Please don't open sockets or the consumer unit, or tape a switch on to stop it tripping. Our fault finding service uses proper testing to find the cause. If the board itself is old or has no RCD protection, a consumer unit upgrade may be worth considering.