Eugene's observations

A significant proportion of my work comes from clients who report sudden loss of one or more hardware components. Where a thunderstorm has recently been nearby or multiple components are affected concurrently, it is usually a good bet that a jolt of electricity has passed up the power, dialup modem or antenna wires.

The power supply units within computers have to handle minor fluctuation as the power is never at exactly 240 volts, but their lives are shortened (sometimes dramatically) by coping with events such as

• Sudden resumption of power after a cut
• Sag (short term under voltage)
• Spike (short term over voltage)
• Brownout (longer term under voltage)
• Overvoltage
• Line noise (electro magnetic interference caused by other equipment)
• Frequency variation (more or less than 50Hz)

Surge protectors are available at all electrical and computer shops, and are designed to protect against these problems and thereby prolong the life of the electrical equipment connected to them. As is common, the more you pay, the better quality of protection you get. About £8 will give the bare minimum protection, but for about £14 it is better to get a device that provides an LED to warn when the device has taken a hit. This is because they normally continue to provide power after the protection has ceased. At that time it is necessary to replace the item. Periodic checks on the (normally green) LED are therefore suggested as part of periodic housekeeping procedures.

To avoid having to replace surge protectors periodically, and provide for a graceful shutdown when a power cut occurs, an uninterruptible power supply (UPS) is preferred. These are basically batteries that feed the PC and are constantly being topped up by the mains. A short power outage - say 10 minutes, will normally not cause the PC to have to be shut down so work may continue. More expensive UPS systems provide power for multiple PCs for a much longer time. Prices start at about £35.

Note that all electrical appliances (e.g. wireless phones, washing machines, TVs) benefit from protection. The cost of replacing surge protectors is normally dwarfed by the cost of repairing or replacing a computer that has taken a hit.