Fuse Board Keeps Tripping? Here's Why

A tripping fuse board is frustrating — but it's actually your electrical system doing its job. Something is causing a fault or overload, and the protective devices are responding correctly. Here's how to work out what's wrong.

Which Device Is Tripping?

Modern consumer units have several types of protective device:

• MCB (Miniature Circuit Breaker): Protects an individual circuit against overloads and short circuits. Trips for that circuit only.
• RCD (Residual Current Device): Protects a group of circuits against earth faults and electric shock. When it trips, everything on that RCD goes off.
• RCBO: Combines MCB and RCD protection in one device — each circuit has independent protection.

Identifying which device is tripping, and whether it trips immediately or after a delay, tells you a lot about the nature of the fault.

MCB Keeps Tripping

Trips immediately: Short circuit — a direct connection between live and neutral, often a damaged appliance, a nail through a cable or a faulty fitting. Call an electrician.

Trips after a delay: Overload — too many appliances on the circuit drawing too much current. Spread the load or have an additional circuit installed.

RCD Keeps Tripping

Trips when a specific appliance is turned on: That appliance has an earth fault and needs to be repaired or replaced. Unplug it and don't use it until it's been checked.

Trips with nothing plugged in: There's a wiring fault — damaged cable insulation, moisture ingress in a fitting or socket, or a faulty accessory. Call an electrician.

Trips when it rains: Water ingress in outdoor electrics — a socket, luminaire or buried cable. Isolate and call an electrician.

What You Should NOT Do

• Don't keep resetting the RCD without finding the cause.
• Don't tape or wedge the RCD in the on position.
• Don't replace a fuse with a higher-rated one.
• Don't ignore repeated tripping — it will get worse and could become dangerous.

When to Call an Electrician

Call an electrician if you can't identify the cause by unplugging appliances; if the device trips with nothing plugged in; if there's any burning smell or visible damage; or if the tripping is becoming more frequent.