Protecting Your Equipment

Computer monitor

We are often asked about electrical equipment that stops working after a power loss. Why does this happen?

When the power comes back on after a power loss, all the appliances and lights come at the same time, which can cause a slight variation in the supply voltage. These variations cannot be controlled.

The normal voltage in the UK is 230 volts, but it isn't constant. The voltage at your property varies constantly due to customers' use of power and normal operation of the power supply network. Our network is designed to ensure that the voltage usually stays within the allowed range. We may supply a voltage outside the range in special circumstances, such as when there is a fault elsewhere on the network and we provide your electricity from an alternative source of power.

Manufacturers of electrical and electronic equipment know about these variations and design their products to cope with them.

As most power losses are outside our control we're not liable for any loss or damage. Your home or business insurance may cover you. We're always happy to confirm the details of a power loss if you can claim on your insurance. The information below provides advice on protecting the types of equipment, which fail most often. Some types of equipment are more sensitive than others to changes in the supply voltage. Electronic items such as:

  • Telephones
  • Fax machines
  • Clock radios
  • Video Recorders
  • Computers
  • Alarm Systems

are more sensitive than other equipment. This is because the internal power supply operates constantly, even when you're not using it.

The constant heat generated in the power supply slowly reduces the ability of the internal parts to withstand voltage variations.

You can protect sensitive equipment from voltage variations by buying a low-cost "anti-spike" lead or adapter. You can buy these from electrical shops and DIY stores. If you're at home when there's a power loss you can protect your equipment by unplugging it or switching off at the socket.

Alarm systems need regular maintenance. Old batteries won't power the alarm for as long as newer ones, so you should replace them every five years.

You may like to consider using an uninterruptible power supply, or UPS, if you work from home using a PC; run a small business which depends on computers or other electronic equipment such as tills. A UPS can give peace of mind for less than £100.

If there's a power loss a UPS uses its battery to keep your computer or other equipment working. It will let you work through short power losses, or shut down your system safely. Many units filter and regulate the power to protect your computer from variations in the supply. Some can save your work and shut down your computer even if you are not there. It is of course still wise to save your work regularly.

You can buy a UPS from a computer supplier or computer supermarket. Ask for help when choosing the size of unit to make sure it is powerful enough for the equipment you want to protect.