If your fuse box keeps tripping, something in your electrical system is triggering a protective device to cut the power. This is the consumer unit doing exactly what it is designed to do. But understanding why it is tripping helps you decide whether it is a simple fix or something that needs professional attention.

Understanding what is tripping

There are two main types of protective devices in your consumer unit:

MCBs (Miniature Circuit Breakers) protect against overcurrent. They trip when a circuit is overloaded (too many appliances drawing power) or when there is a short circuit (a live wire touching a neutral or earth wire).

RCDs (Residual Current Devices) protect against earth faults. They trip when current leaks from the circuit to earth, which usually means a cable is damaged, an appliance is faulty, or someone is getting an electric shock. RCDs are much more sensitive than MCBs and can trip at very low fault levels.

If your board has RCBOs, these combine both functions in one device for each circuit.

Common causes of tripping

A faulty appliance

This is the most common cause. A faulty appliance can leak current to earth, tripping the RCD. Common culprits include:

Washing machines and dishwashers (moisture and vibration damage seals over time)
Kettles and toasters (heating elements degrade)
Fridges and freezers (compressor faults)
Electric showers (water ingress to the heating element)
Outdoor equipment (lawnmowers, pressure washers used in wet conditions)

What to try: Unplug all appliances from the affected circuit and reset the breaker. Plug them back in one at a time to identify which appliance causes the trip.

An overloaded circuit

If an MCB trips (not the RCD), you may simply have too much load on one circuit. This is common in kitchens where a kettle, toaster, and microwave are all on the same circuit.

What to try: Reduce the number of appliances running simultaneously on that circuit. If the tripping stops, the circuit is overloaded rather than faulty.

Moisture or water ingress

Water and electricity do not mix. Common scenarios include:

Rain getting into an outdoor socket or junction box
A leak dripping onto wiring in the ceiling or walls
Condensation in a bathroom extractor fan
A washing machine leak reaching a socket behind the unit

What to try: Check for any visible signs of water near sockets, switches, or the consumer unit. If you find water, stop using the affected circuit and call an electrician.

Damaged wiring

Cables can be damaged by:

DIY work (drilling into a cable hidden in a wall)
Rodent damage (mice and rats gnawing through cable insulation)
Age (insulation degrading over decades)
Movement (cables in areas that flex, such as under floorboards that are walked on)

This is not something you can fix yourself. If you suspect damaged wiring, you need a fault finding inspection.

A faulty protective device

Occasionally, the MCB or RCD itself can develop a fault and trip without a genuine cause. This is more common with older devices that have tripped hundreds of times over their lifespan. Replacing the device resolves the issue.

When to call an electrician

Call an electrician if:

The RCD trips immediately every time you reset it
You cannot identify which appliance is causing the trip
The tripping started after DIY work or building work
You see scorch marks, smell burning, or feel warmth at the consumer unit
Multiple circuits are tripping at the same time
The tripping is intermittent and you cannot find a pattern

Do not repeatedly reset a tripping RCD without investigating the cause. The RCD is protecting you from a fault. Overriding it by holding the switch or taping it in place is extremely dangerous.

What about the main switch?

If the main switch on your consumer unit trips (cutting power to the entire house), this is different from an individual circuit tripping. It usually indicates a fault on the incoming supply or a serious fault within the consumer unit itself. Contact your electricity distributor (not your energy supplier) or an electrician.

Can I fix it myself?

You can safely:

Reset a tripped MCB or RCD
Unplug appliances to identify a faulty one
Check for obvious signs of water ingress

You should not:

Open the consumer unit beyond the cover
Touch any wiring or terminals
Bypass or tape down a tripping device
Ignore repeated tripping

Next steps

If your fuse box keeps tripping and you cannot identify the cause, contact us for a fault finding appointment. We use systematic testing to locate the fault efficiently, and in most cases we can diagnose and fix the problem in a single visit.

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Fuse Box Keeps Tripping: Causes and What to Do