Why does my electric keep tripping? Fuse box and RCD causes, and what to do

Which switch tripped: RCD or circuit breaker?

Open your fuse box and look for the switch that's down. RCDs are usually wider switches with a test button marked T, and each one protects a group of circuits. Circuit breakers (MCBs) are the narrower switches, one per circuit. Some boards use RCBOs, which combine both for a single circuit. Older fuse boxes may have fuse wire or cartridge fuses instead.

A circuit breaker usually trips because a circuit is overloaded or there's a short circuit. An RCD trips because current is leaking to earth. Knowing which one went helps narrow down the cause.

The most common causes

• A faulty appliance. Kettles, toasters, washing machines, dishwashers, immersion heaters and old extension leads are frequent culprits.
• Water or damp. Outdoor lights and sockets, bathroom fittings and anything near a leak can let moisture in.
• Damaged cable. A nail or screw through a cable, or a cable damaged during building work.
• Too much on one circuit. Heaters, kettles and other high-power appliances on the same circuit can overload it.
• Lots of small leakages adding up. Many appliances on one RCD can trip it between them.
• A worn-out RCD or breaker. Less common, but they can fail with age.

How to find the culprit safely

1. Unplug everything on the circuits that went off. If you're not sure which ones, unplug everything you can.
2. Reset the RCD or breaker once.
3. If it stays on, plug appliances back in one at a time. If it trips when one goes back in, that appliance is the likely cause: leave it unplugged and get it checked or replaced.
4. If it trips straight away with nothing plugged in, the fault is in the fixed wiring or a fitting. Leave it off and call an electrician.

Never tape, wedge or hold a switch in the on position. It's switching off to protect you.

Why does my electric trip at night?

Usually because something switches on by itself overnight: a fridge or freezer compressor, a storage or immersion heater on a timer, or an outdoor light on a sensor. If the trip happens around the same time each night, think about what runs then.

Why does my electric trip when it rains?

Almost always because water is getting into something outside: an outdoor light, socket, garden lighting, a shed supply or a cable run. The fitting or cable needs checking, drying out and resealing or replacing, and outdoor circuits must be RCD protected.

Why does it trip randomly, or every few hours?

Intermittent trips are the hardest to trace. They're often caused by an appliance that only faults when it heats up or cycles on, damp that comes and goes, or a loose connection. An electrician can test each circuit's insulation and narrow it down, which is quicker and safer than repeatedly resetting.

Fuse box humming, clicking or smelling of burning

A faint hum from some boards can be normal, but loud buzzing, crackling, clicking, a hot case, scorch marks or a burning smell are warning signs of a loose connection or an overheating component. If it's safe to do so, switch off at the main switch and call an electrician straight away. If there's smoke or fire, get everyone out and call 999.

When it's an emergency

Call an electrician straight away if you can smell burning, see scorch marks or sparking, if water has got into a fitting or the fuse box, or if you've lost power to essential circuits and can't restore it. If your neighbours have lost power too, it's a power cut: call 105.

Need a hand?

E.A Electrician Ltd is a North London electrical company based in Wood Green, N22, rated 5.0 from 32 Google reviews. See our 24/7 emergency electrician service, or call 07871 056970 for a free estimate.

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Published by E.A Electrician Ltd. Last updated 1 November 2026.