Why does my RCD keep tripping?

Why Does My RCD Keep Tripping? An RCD (Residual Current Device) is the safety switch in your consumer unit (fuse box) that protects you from electric shock and fire. It constantly monitors the electrical current flowing through a circuit, and if it detects even a tiny imbalance — as little as 30 milliamps leaking to earth — it cuts the power in milliseconds. When it trips, it's doing its job. The question is why. Most Common Causes Faulty appliance — A damaged kettle, washing machine, dishwasher, or electric shower is the number one cause. Internal insulation breaks down over time, allowing current to leak. Wet or damp conditions — Water ingress into outdoor sockets, garden lighting, or garage circuits is extremely common, especially after rain. Overloaded circuit — Though more typical of MCBs, some combined RCBO units can trip under load. Old or deteriorating wiring — Aged rubber-insulated cables or damaged conductors can cause intermittent earth faults. The RCD itself is faulty — RCDs have a lifespan and can become oversensitive or fail mechanically. What You Can Safely Do 1. Unplug every appliance on the affected circuit (check which circuit by looking at which RCD tripped). 2. Reset the RCD — push the lever firmly upward. 3. Plug appliances back in one at a time, waiting a moment between each. 4. When the RCD trips again, the last appliance plugged in is likely the fault. Stop using it and have it tested or replaced. When to Call an Electrician The RCD won't reset at all, even with everything unplugged. The RCD trips immediately with nothing connected. The RCD trips randomly with no apparent pattern. You suspect damp or water damage in the wiring. The RCD has been tripping for years — this is not normal and needs investigation. Never ignore a repeatedly tripping RCD. It is warning you of a potentially dangerous fault. A registered electrician (look for NICEIC or NAPIT registered) can diagnose the problem safely.