RCD Keeps Tripping? Causes & How to Fix It

⚡ What is an RCD and Why Does It Trip?

An RCD (Residual Current Device) is a safety device in your consumer unit (fuse box) that instantly disconnects power if it detects a leakage current — protecting you from electric shocks and preventing fires.

An RCD trips when it detects electricity going somewhere it shouldn't — such as through a person, a faulty appliance, or damaged wiring.

RCDs save lives. If your RCD trips, something has caused it to trip — it's not a fault with the RCD itself (usually). Find and fix the underlying cause.

🔍 How to Find Which Circuit is Tripping Your RCD

Step 1 — Note what was happening when it tripped

Was it when you switched something on? Turned the kettle on? Stepped out of the shower? This gives a big clue.

Step 2 — Identify which RCD tripped

Modern consumer units have two RCDs covering different circuits. The one that's tripped will be in the down position.

Step 3 — Isolate circuits one by one

Turn off all the MCBs (individual circuit breakers) under the tripped RCD
Reset the RCD — it should stay up now
Turn MCBs back on one at a time
When the RCD trips again, the last MCB you turned on is the faulty circuit

Step 4 — Identify the faulty appliance

Unplug everything on the faulty circuit, reset the RCD, then plug appliances back in one by one until it trips again — that's your faulty appliance.

🏠 Common Causes of RCD Tripping

Cause	When it Trips	Fix
Faulty appliance	When appliance is plugged in/switched on	Replace appliance
Damaged extension lead	When lead is plugged in	Replace lead
Water in sockets/fittings	Often in bathroom/kitchen circuits	Dry out, call electrician
Damaged wiring	Randomly or when circuit is loaded	Electrician required
Faulty RCD itself	Trips with no load at all	Replace RCD
Old wiring (no insulation)	When circuits are loaded	Rewire required

If your RCD trips even with all MCBs off, the RCD itself may be faulty and needs replacing. Call FE Maintenance on 020 8445 1303.

RCD Keeps Tripping? Here's Why