An RCD trips for one reason: it has detected electricity leaking somewhere it shouldn't be, often through a faulty appliance, damaged cable or moisture. That's the device doing its job. The trick is working out what's causing it.
Here's the safe way to narrow it down yourself, without opening anything or touching a single wire.
Step 1: Unplug, then reset
Unplug every appliance you can reach on the affected circuits: kettle, toaster, washing machine, dishwasher, chargers, lamps, the lot. Then try resetting the RCD.
If it stays on with everything unplugged, one of your appliances is the likely culprit. If it trips again immediately with nothing plugged in, the fault is in the fixed wiring, and it's time to stop and call an electrician.
Step 2: Plug things back in, one at a time
Reconnect appliances one by one, waiting a moment between each. When the RCD trips again, you've found your suspect. Leave that appliance unplugged and see if the problem disappears.
Appliances with heating elements are the usual offenders: kettles, washing machines, dishwashers, tumble dryers and immersion heaters. Elements absorb moisture as they age and leak current long before they stop working.
The usual suspects
- Kettles and small appliances with worn elements or damaged flexes
- Washing machines, dishwashers and dryers, especially mid-cycle when the element heats up
- The immersion heater, a classic cause of early-morning tripping on a timer
- Outdoor sockets, lights and pond or garden equipment after rain
- Extension leads and adaptors that have been damaged or soaked
- Rodent-damaged cables in attics and under floors
When it's more than a nuisance
Call a registered electrician straight away if the RCD won't reset with everything unplugged, if tripping is paired with a burning smell, buzzing or scorched fittings, or if water has got into any part of the installation.
Frequent random tripping with no obvious cause is also worth investigating properly. Sometimes it's cumulative leakage from many ageing appliances sharing one RCD. Splitting circuits across individual RCBOs usually cures it for good, and it's one of the most common small jobs we do.
Never tape down, hold in or bypass a tripping RCD, and never move fuse wire or parts around inside the board. If it keeps tripping, it keeps tripping for a reason.
Stuck?
If you've worked through the steps and the problem is still there, that's what we're for. Fault finding is detective work, and with the right test equipment it's usually solved in a single visit. Give us a call and we'll get you sorted.