Homeowner guide
How to reset a tripped RCD
An RCD (Residual Current Device) trips to disconnect the supply when it detects current leaking to earth — usually because an appliance has failed or water has got into a circuit. Here's how to find the cause without guessing, and when to stop and call.
Open the consumer unit and identify what's tripped
An RCD (or RCBO) trips down to the OFF position. Its main switch stays up. Note which device tripped — main RCD, one side of a split-load board, or a single RCBO.
Turn OFF every MCB on the affected side
If a whole-side RCD has tripped, switch every MCB below it to OFF before trying to reset. This isolates the fault so you can bring circuits back one at a time.
Reset the RCD
Firmly push the RCD switch back to ON. If it won't stay up even with every MCB off, the fault is inside the consumer unit — stop and call an electrician.
Bring MCBs back on one at a time
Switch each MCB back to ON, waiting a few seconds between each. The one that trips the RCD again is on the faulty circuit. Leave that MCB OFF and turn the RCD back on.
Find the faulty appliance on that circuit
Unplug everything on the suspect circuit. Reset the MCB. Plug appliances back in one at a time — the one that trips the RCD is the culprit. Stop using it and have it PAT tested or replaced.
If nothing is plugged in and it still trips
The fault is in the fixed wiring — damaged cable, water in an outdoor fitting, faulty light fitting or accessory. Leave that MCB off and call an electrician for a fault-find.
Safety rules
- Never bypass a tripped RCD or wedge it in place — it's protecting you against electric shock.
- If you smell burning, see scorch marks or the consumer unit itself is warm — do not reset. Turn the main switch OFF and call.
- If the RCD trips again the moment you press it with every MCB off, stop resetting. Repeated tripping under fault current can damage the device.