Why is my RCD tripping but the electrician can't find the fault – Advice from Electriman, North London Electricians

## Why Your RCD Keeps Tripping But the Electrician Can't Find the Fault

This is one of the most frustrating electrical problems a homeowner faces. Your RCD (Residual Current Device) is doing exactly what it should — detecting a leakage of current to earth — but the fault is either **intermittent**, **very small**, or spread across **multiple sources**, making it hard to pin down during a routine visit.

### What an RCD actually does

An RCD monitors the difference between current flowing out through the live wire and returning through the neutral. If more than **30mA** escapes (to earth or through a person), it trips instantly to protect you. Something doesn't have to be dramatically wrong for it to trip.

### Common reasons it's hard to find

- **The fault only appears under load or heat** — wiring insulation that's fine when cold can break down when warm

- **Damp or moisture** — a wet garden cable, a damp outdoor socket, or condensation in a light fitting can cause leakage that dries out before the electrician arrives

- **Ageing appliances** — washing machines, dishwashers, electric ovens, and immersion heaters develop small earth leakage over time

- **Cumulative leakage** — each appliance on a circuit may pass individual tests, but together they exceed the RCD threshold

- **Time-of-day patterns** — if it trips at night, suspect a storage heater, overnight appliance, or moisture build-up

- **Faulty RCD itself** — RCDs can bec

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