Why Does My RCD Keep Tripping?
An RCD that keeps tripping is doing its job — it has detected electricity leaking where it should not. But repeated nuisance tripping is frustrating and usually points to an underlying fault. Here is how to narrow down the cause safely, and when to call a Cardiff electrician.
What an RCD does
A residual current device monitors the balance between live and neutral current. If it detects a difference — meaning some current is leaking to earth, possibly through a person — it disconnects the supply in milliseconds. That sensitivity is exactly what makes it life-saving, and also why it trips so readily.
Common causes of nuisance tripping
- A faulty appliance leaking small currents to earth (kettles, washing machines, fridges).
- Moisture in an outdoor socket, garden light or shed circuit.
- Ageing cable insulation lowering resistance, especially in damp walls.
- A neutral-to-earth fault on a shared circuit.
- A circuit genuinely overloaded or a damaged cable.
Safe checks you can do first
Switch off and unplug all appliances on the affected circuit, then try to reset the RCD. If it holds, reconnect appliances one at a time to identify the culprit. Never bypass an RCD or tape a breaker to stop it tripping.
When to call an electrician
Call a professional if the RCD will not reset with everything unplugged, if it trips repeatedly with no clear cause, or if you notice a burning smell, scorch marks or heat from the board. These can indicate a fault in the fixed wiring that needs instrument testing to locate.
How professional diagnosis works
Using a calibrated multi-function tester we carry out insulation resistance testing, RCD ramp testing and circuit-by-circuit isolation to pinpoint the exact source of leakage — whether a degraded cable, a crossed neutral or a damp fitting — then quote for a permanent repair before any work starts.
Frequently asked questions
Can I just replace the RCD with a higher-rated one to stop it tripping?
No. An RCD is a safety device calibrated to disconnect on small earth leakage currents. Upsizing or bypassing it removes that protection and is unsafe. The correct fix is to find and repair the cause of the leakage.
Why does my RCD only trip when it rains?
Moisture getting into outdoor sockets, garden lighting or aged cable insulation lowers resistance to earth and triggers the RCD. A fault-finding visit can isolate the affected circuit and repair or replace the damaged section.
Related services
Available across Cardiff and the Vale of Glamorgan.
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