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How to check an electrical system is safe

Introduction

There are some tell-tale signs that your system is out of date and unsafe to work on (old-style rubber-sheathed cable, for example). But even if you live in a modern house with an electrical system that's been professionally checked and approved in the past ten years, things can still go wrong. So make sure it's safe before you begin work.

If you're in any doubt, get it checked by a qualified electrician.


For your safety, electrical products must be installed in accordance with local Building Regulations. If in any doubt, or where required by the law, consult a competent person who is registered with an electrical self-certification scheme. Further information is available online or from your Local Authority.

Never take risks with electrical safety. Before you start any type of electrical work, you must follow these following safety precautions:

  • Switch off the main power at the consumer unit/fuse box. Isolate the circuit you plan to work on by removing the circuit fuse. Put this in your pocket to avoid accidental replacement
  • Or switch off the breaker and lock it if you can
  • Attach a note to the unit to advise you are working on the circuit
  • Check the circuit is dead with a socket tester or voltage tester/meter for lighting circuits 

If your consumer unit cover gets cracked or broken, ensure that you replace it straight away. In older houses, you sometimes find a mixture of old fuse boxes attached to the fuse board beside the electricity meter. These can be dangerous, and we'd strongly advise you to get a qualified electrician to change them for a modern all-in-one consumer unit.


If you need to do some electrical work in your home, you'll need to isolate the circuit you're working on by removing the correct fuse or switching off the circuit breaker. If the circuits aren't already labelled, you can do this yourself. Identify each one by switching off the main power, disabling one circuit, restoring the power and then investigating which sockets, appliances or lights are dead.


Cables used to be sheathed in rubber, which perishes over time and can potentially expose bare wires. If you have rubber cabling, or if any cables are worn, get them checked by a qualified electrician and replaced if necessary. If you've got modern cabling that's become discoloured, this could be a sign of overheating - so have it inspected by an electrician.


You'll see a thick cable with green and yellow sheathing (or green in an older installation) running from your consumer unit. This provides the vital earth connection. If this cable looks at all loose or damaged, it's important that you get it checked straight away.


A residual current device (or 'RCD') will detect an earth leakage and isolate a circuit in milliseconds, before an accident can occur. You can check if your RCD is working properly by pressing its test button.


Fixed wiring runs in the walls, between floors and in your loft space. If you can get access to any part of it, check its condition. Is it rubber-insulated? Are any bare wires showing? Is it fixed securely? Does it run neatly into any junction boxes or accessories? If you have surface-mounted wiring, it should be clipped tidily to the walls, or preferably concealed behind them.


Watch out for any warning signs that a connection may be loose inside. Does the socket or plug feel warm? If so, you should check the connections inside the socket and plug, or contact an electrician for advice.

If it's difficult to insert a plug into a socket, it could be a sign that the socket is worn and needs to be replaced. Try to replace a cracked or broken faceplate on a socket as soon as possible.

Scorching on a socket can be caused by overloading - for example, by plugging in an adaptor to supply several large loads, or by loose connections in a plug. Replace the faceplate and investigate the cause of the problem. Then reduce the load and replace the plug if necessary.


Even if an appliance appears to be working normally, it's well worth checking the wiring from time to time. Is the insulation around the flex deteriorating? Is the flex securely attached? Are there any bare wires visible? Make sure that the earth cores have green and yellow sleeving.

If the external casing of an appliance has become cracked or worn, you'll need to replace it. If the switches aren't working properly, get professional help or a new appliance. Also, make sure the plug contains a fuse of the correct rating for the appliance in question.


If there isn't an earth wire inside your ceiling rose, get an electrician to check it. If you have old-style braided flex, you'll need to replace it with the correct PVC-insulated and sheathed version.


If you use any of your portable electrical appliances outdoors, they must be protected by a 30mA RCD. Equally, your outdoor sockets must be protected by an integral RCD, or one that's permanently wired into the circuit. If you have an indoor socket that you use to power appliances outdoors which doesn't have RCD protection, you must use a plug-in RCD.