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

It can be really frustrating when your RCD keeps tripping but your electrician visits and finds nothing wrong. The good news is this is a recognised and very common problem, and there are logical reasons why it happens.

An RCD (Residual Current Device) is the switch in your consumer unit that trips when it detects a small amount of electricity leaking to earth. It is designed to protect you from electric shock. It is extremely sensitive, typically operating at 30 milliamps, which is a very small amount of current.

Why faults can be invisible during a visit

The key word here is intermittent. Some faults only appear when conditions are right. A cable with slightly damaged insulation might only leak current when it is damp, warm, or under load. An ageing appliance might only misbehave after it has been running for 20 minutes. This is why the electrician tests everything, finds nothing wrong, and then the trip happens again the next morning.

Some common reasons the fault hides itself include:

1. Moisture in an outdoor socket, garden cable, or bathroom fitting that dries out before the visit.

2. An appliance such as a washing machine, dishwasher, or electric shower that only develops a fault under heat or load.

3. Accumulated leakage from multiple healthy appliances — each one leaks a tiny amount, and together they nudge the RCD over its threshold.

4. A loose connection that only makes poor contact at certain times.

5. Undergr

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Electriman covers Mill Hill, Barnet, Finchley, Edgware, Enfield, Watford and surrounding areas. All work is Part P certified and fully insured.