RCD or trip switch keeps tripping: how to find the faulty circuit
Quick answer
An RCD that keeps tripping is detecting a real leak of current, usually from one faulty circuit or appliance. Switch every breaker off, reset the RCD, then turn breakers back on one at a time. The one that trips it carries the fault: leave it off. If it trips with everything off, will not reset, or you smell burning, call 07703 295654.
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Why the trip switch keeps going off
An RCD trips when electricity is leaking somewhere it should not go, often through damp, damaged cable or a failing appliance. It is doing its job. The task is to find which circuit carries the fault, not to hold the switch on.
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Find the faulty circuit safely
Switch every individual breaker on the board off, then reset the RCD. Turn the breakers back on one at a time, pausing between each. When the RCD trips, the last breaker you touched feeds the faulty circuit.
Leave that breaker off and reset the rest. If the faulty circuit is sockets, unplug everything on it and try again. A single appliance is often the culprit: kettles, washing machines and outdoor lights lead the list.
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When to stop and call
Stop if the RCD trips with every breaker off, if it will not reset at all, if anything smells hot, or if water has been anywhere near the board or sockets. Those faults sit in the fixed wiring and need proper test equipment.
Stop too if you simply do not feel confident. Nobody sensible pokes at a live board at 2am.
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What we do when we arrive
We test each circuit with proper instruments, find the leak and either repair it there and then or isolate it safely, with a fixed quote for the repair.
Related questions
Why does my RCD trip when it rains?
Water is getting into something on that circuit: an outdoor socket, garden lights, a cable to an outbuilding, or a junction box in a damp spot. Leave the affected breaker off and have the outdoor circuit tested.
Is it safe to keep resetting a trip switch?
Once is fine. Repeated resetting pushes current into a fault and can damage cables or appliances. If it trips again, leave it off and find the cause.
What is the difference between an RCD and an MCB?
An MCB (a normal breaker) trips when a circuit draws too much current, such as an overload or short circuit. An RCD trips when current leaks to earth, which is what happens with damp, damaged cable or a faulty appliance, and it is what protects you from a shock.