The connected load of an electrical installation is generally more than its actual maximum demand at any time. The reason is the liberal provisions made for loads that are to be used occasionally – spare feeders, maintenance power sockets and some reserve capacity available with most of the outgoing feeders. Moreover, some of the feeders may be operating under loaded. To design a switchgear assembly, particularly for its incoming feeder and the busbar ratings, based on the connected load would be neither economical nor prudent, and the protective scheme too would under-protect such a system. Based on experience, IEC 60439-1 has suggested a multiplying factor, known as the