Fuse box keeps tripping? Why it happens and when to call an electrician

Why fuse boxes trip

Modern fuse boxes (consumer units) have switches that cut the power when something goes wrong. That's a safety device working, not a fault in itself. There are two types you'll see:

• Circuit breakers (MCBs), one per circuit, labelled things like "sockets", "lights" or "cooker". They trip when a circuit draws too much current.
• RCDs, usually wider switches with a test button. They trip when electricity is leaking somewhere it shouldn't, which is exactly what protects you from a shock.

The common causes

• A faulty appliance. Kettles, washing machines, ovens, immersion heaters and outdoor equipment are the usual ones.
• Too much on one circuit. Heaters, kettles and tumble dryers all at once.
• Water or damp, especially in outside lights, outside sockets, or anywhere near a leak.
• Damaged wiring. A nail or screw through a cable, or rodents chewing wires in the loft.
• A worn socket, switch or light fitting.

A safe way to narrow it down

1. Switch off and unplug everything on the circuit that tripped.
2. Reset the switch at the fuse box.
3. Plug things back in one at a time. If it trips when a particular appliance goes on, that appliance is the likely culprit. Leave it unplugged.

If it trips with nothing plugged in, the fault is in the wiring itself. That's a job for a qualified electrician. Don't keep resetting it.

Call an electrician straight away if

• It trips again with nothing plugged in.
• There's a burning smell, scorch marks or buzzing from a socket, switch or the fuse box.
• Water has got into any electrics.
• A switch won't reset at all.
• Your fuse box is old, with wire fuses instead of switches.

Never hold a switch up, tape it in place, or swap a fuse for a bigger one. The trip is protecting you.

Power out on the whole street?

If the neighbours are out too, it's a power cut, not your fuse box. Call 105, the free power cut line.

Common questions

Is it dangerous if my fuse box keeps tripping?

The tripping is the safety system working. The fault causing it can be dangerous, especially with a burning smell or water involved, so get it checked.

Why does my RCD trip at night or when it rains?

Usually damp getting into outside lights, sockets or cables. It needs an electrician to find and fix.

Can I replace a faulty socket myself?

Some minor work is allowed, but if you're not trained, call an electrician. Electrical faults can cause fires and shocks.