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How to trace an electrical fault

There are a number of common causes of electrical faults so we've provided an overview of the most likely causes. Work your way through these troubleshooting steps to see what your problem is likely to be. But remember, it's always best to call in a qualified electrician to carry out the actual repair.

How to trace an electrical fault

Top tip

  • Make a note of which fuses or circuit breakers control the different areas of the house so that you can quickly find any faults. Label the fuses or circuit breakers clearly to save any confusion.

Blown fuse in the consumer unit
If wires in your home or appliances overload the wiring, you are protected by either fuses or circuit breakers at the consumer unit that cut off the power as soon as the overload is detected.

Normally there is a separate circuit for the downstairs sockets, downstairs lighting, upstairs sockets and upstairs lighting. There are almost always extra circuits to protect bathroom electrics and other appliances.

Older systems use fuses that melt, and these must be replaced by a new fuse of the same rating after you have dealt with the cause of the fault.

Newer systems use small circuit breakers that trip when overloaded. They are reset by either pushing in a button or flipping a switch. Again, always deal with the cause of the problem or call in an electrician.

Check the individual circuit
If a fuse or circuit breaker does cut off the power, it may be that there are too many appliances on that circuit or that the load is too great.

Take out the fuse or leave the circuit breaker in the off position while you check the circuit. Try unplugging one appliance at a time and switching the power back on to discover if one item is overloading the circuit. If you can't find the source of the problem, call in an electrician. Faulty switch or socket Sockets and switches should always be replaced if they are cracked or damaged in any way. You should also look out for any black deposits that indicate a faulty connection. Turn off the power and remove the cover plate and tighten any loose wiring connections. It's important to check the plugs used with a socket are in good condition with tight wiring connections. Mains voltage tester You can buy a mains voltage tester to check if a section of wiring or a socket is live. These testers should always be tested on a circuit that is live to check that it is working properly before you check a suspected fault. If you aren't confident about using one of these testers or fixing the problem yourself, always call in an expert. For more information see the Electrical Contractors Association.