RCD Tripping? Causes & How to Fix It
A residual current device that keeps tripping means there is a real earth fault somewhere on your installation. Here's how we find it — and why a full RCBO board is the permanent fix.
Never bypass a tripping RCD
Some unscrupulous tradespeople will swap a tripping RCD for a non-RCD MCB to "make it work". This is illegal, dangerous and will fail any future EICR. Always have the underlying fault diagnosed.
Top 7 causes of RCD trips
- Faulty kettle, washing machine or dishwasher leaking to earth
- Water ingress in an outdoor socket, garden lights or shed wiring
- Failed immersion heater element in the hot water cylinder
- Damaged cable — nail/screw through a wall, rodent damage, age
- Moisture inside an external or bathroom light fitting
- Cumulative leakage from many electronics on the same RCD (LEDs, chargers, TVs)
- The RCD itself has reached end of life (15–20 years)
RCD controlled circuits — what's protected?
In a UK home an RCD must protect every socket likely to feed equipment outdoors, all bathroom circuits, all cables buried less than 50mm in walls, and all final circuits in domestic premises (BS 7671 18th Edition). That is essentially every circuit in the house — which is why one RCD trip takes out so much.
Tripping RCD? We'll find the fault — same week
Insulation resistance & earth fault loop testing. Devon-wide. CHAS approved.
Frequently Asked Questions
Why does my RCD keep tripping?
An RCD (Residual Current Device) trips when it detects current leaking to earth — usually 30mA or more. The most common causes are a faulty appliance, water in an outdoor socket, a damaged cable, a failing immersion heater element, or moisture in a light fitting. Sometimes the RCD itself has aged out (typical life 15–20 years).
How do I find which appliance is tripping the RCD?
Unplug everything on the affected circuits, reset the RCD, then plug appliances back in one at a time until it trips. If it trips with nothing plugged in, the fault is in the fixed wiring — call us for an insulation resistance test.
Is it dangerous if my RCD keeps tripping?
The RCD doing its job is not dangerous — that is exactly what it is designed for. What is dangerous is bypassing it or ignoring repeated trips. Repeated trips indicate a real earth fault that needs locating before it causes a shock or fire.
What is a residual current device?
A Residual Current Device (RCD) is a life-saving switch in your consumer unit that disconnects the supply within 40ms if it detects electricity leaking to earth — typically because someone has touched a live part or an appliance is faulty.
Should I replace my dual RCD board with RCBOs?
Yes — we strongly recommend a full RCBO consumer unit. With a dual RCD board one fault knocks out half the house. With RCBOs only the faulty circuit trips. Full RCBO upgrades from £650 plus VAT.