Why Does My RCD Keep Tripping? London Electrician's Guide

An RCD (Residual Current Device) measures the current flowing out of your installation versus the current coming back. If they differ by more than 30 milliamps, that current is going somewhere it shouldn't — usually through a person, water, or damaged insulation.

A tripping RCD is doing its job. Never bypass it. Find the cause.

1. A faulty appliance. By far the most common. Anything with a heating element or motor (washing machine, dishwasher, kettle, hairdryer, vacuum) is the usual suspect.

2. Water ingress. Shower pull-cords with damp inside, outdoor sockets after rain, leaks above ceiling-mounted fittings.

3. Damaged cables. Stapled-through by a careless picture-hanging, rodent-chewed, or perished by age.

4. Worn-out lamp holders or pendant fittings.

5. Overloaded earth leakage from multiple LED drivers, motors and IT loads on one RCD (a "nuisance trip").

6. A failing RCD itself (rare, but happens with older devices).

7. Storm-induced trips from grid surges (one-off, resets after the storm).

Unplug everything on the affected circuit. Reset the RCD. Plug appliances back in one at a time. The one that trips it again is your culprit.

Do NOT remove your fuse-board cover, do NOT poke testers into terminals, do NOT bypass the RCD with a jumper.

If the unplug-and-test approach doesn't find the fault, or if the trip happens with everything unplugged, you have an installation fault — damaged cable, leaking joint, failing accessory — and need diagnostic testing. Our fixed-fee £90 diagnostic covers most domestic faults in the first hour.