Usually one appliance has a fault: often a kettle, washing machine, oven, immersion heater or outdoor light. Unplug everything on the circuit that tripped, reset it, then plug things back in one at a time until it trips again. If it trips with everything unplugged, the fault is in the wiring and needs an electrician.
Stop first if you see any of these
Find it in ten minutes
- See what tripped. A single breaker, an RCD (it has a test button), or the main switch. Note which one is down before you touch anything.
- If it is a single breaker, unplug everything on that circuit. For a kitchen or utility, that means the kettle, toaster, washing machine and dishwasher too.
- Reset the breaker. If it stays on, plug appliances back in one at a time. When it trips again, the last thing you plugged in is your suspect.
- If an RCD tripped, switch off every breaker below it, reset the RCD, then switch the breakers back on one at a time. The one that trips the RCD is the circuit with the fault. Then unplug things on that circuit as above.
- If it trips with nothing plugged in, or trips the moment you reset it, the fault is in the fixed wiring or a fixed appliance like an oven, shower or immersion heater. That is a job for an electrician.
The usual suspects
| Cause | Tell-tale sign |
|---|---|
| Kettle, toaster or iron | Trips when it is switched on, often after limescale or water gets into the element |
| Washing machine or dishwasher | Trips part way through a cycle, when the heater comes on |
| Oven or hob | Trips when heating up, especially after cleaning or a spill |
| Immersion heater | Trips overnight or on a timer |
| Outdoor lights and sockets | Trips when it rains, or the morning after |
| A nail or screw through a cable | Started after a shelf, picture or kitchen went up |
| Too much on one RCD | Random trips with no pattern, on an older dual-RCD board |
When the board is the problem
Two things point at the board rather than an appliance. First, an RCD that is wearing out can trip at a lower leakage than it should, and an electrician can measure that. Second, a dual-RCD board adds up the normal leakage from everything on its side, and in a modern home that can be enough to trip it with nothing faulty at all.
The fix for both is the same: an RCBO on every circuit, so each circuit only carries its own leakage and a fault only switches off the circuit it is on. Read RCD or RCBO for why, or send us three photos for a fixed price from £449.
If you need the fault itself found first, our sister company Wired & Certified does fault finding from £95.
