RCD keeps tripping: causes and what you can safely check yourself
The most common causes
An RCD trips when current is leaking to earth. That leak has to come from somewhere:
- A faulty appliance. Washing machines, dishwashers, boilers and older fridges are the usual suspects.
- Moisture. An outdoor socket, garden lighting or a damp cellar, typically after heavy rain.
- Accumulated small leaks. Several appliances each leaking a little, together crossing the threshold.
- A damaged cable. A screw or nail through a wall is a classic.
- A worn RCD. They do age, and after twenty years they can trip on their own.
What you can safely test yourself
Switch every breaker on that RCD off. Reset the RCD. Now switch the breakers back on one at a time. The one that trips it identifies the circuit. Then unplug the appliances on that circuit and add them back one by one. This tells you where the fault is without opening anything.
When to call an electrician straight away
Call immediately if the RCD will not reset at all, if you smell burning, if a socket or the board is warm, or if it trips with everything unplugged. In those cases the fault is in the fixed wiring rather than an appliance, and that is not something to investigate yourself.
Prevention
Test the RCD every six months with its test button, keep outdoor sockets properly covered, and replace appliances that trip it repeatedly rather than working around them.
Veelgestelde vragen
Why does my RCD trip after rain?
Almost always moisture in an outdoor socket, garden lighting or a poorly sealed junction box. Water creates exactly the leakage path the RCD is built to detect.
Can I just switch it back on?
Once, yes. If it trips again straight away, stop and work out which circuit is responsible — repeatedly resetting it defeats the protection.
How do I test whether my RCD works?
Press the test button on the device itself. It should trip immediately. Do this every six months.
Can an RCD fail by itself?
Yes. They are mechanical devices and wear out. After about twenty years, unexplained tripping is often the RCD itself.