Most commercial and industrial businesses, and also research organizations, are nowadays heavily dependant on electronic data processing equipment in the form of electronic calculators, word processors, personal computers, which in some instances are linked directly to mainframes, and terminals which are linked directly to mainframes. Data processing equipment, for efficient operation, requires clean power, that is, power which is free of surges, spikes and other irregularities in voltage and current. Such power is expensive to provide and it is not generally desirable to use it for non-sensitive equipment such as typewriters and tasklights as this greatly increases the size of the supply installation required.
The equipment found in an office complex is often manufactured in a number of different countries. Most countries in the world have their own style of power plug. Two and three pin plugs are widely used. Two pins plugs are mainly used for non-earthed 100-110 volt supplies and three pin plugs for earthed supplies of higher voltage e.g. 220-250 volts. However, there are two pin plugs for use on 220-250 volt and three pin plugs for 100-110 volt supplies. The spacing between and the size of the pins of two pin plugs varies from country to country. Likewise the cross-sectional shapes of the pins of three pin plugs, and their spacing and position, varies from country to country.
Most electronic equipment is supplied with a power cable one end of which is within the casing of the electronic equipment and the other end of which has a sealed plug on it. The plug is that in use in the country of manufacture. The end user in another country, not having power sockets of the appropriate type, quite often cuts off the plug and attaches a plug of the type in use in his country. The problem with this is that, if the electrical connections are not properly made or come loose, arcing can occur. This introduces irregularities into the clean power supply which affects not only the piece of equipment in question but all other equipment being fed from that line.