, as an afterthought. tive, allowing a plants' status to be changed by remote commands Traditionally, and in many respects from a practical and economic (Nightingale, 1985; Mealing, 1984; Wittey, 1986). Additionally point of view, major items of power plant tend to be located on the such systems can be linked with energy (say heating) and environ- ground floor, or where available, the basement of a building. mental (air conditioning perhaps) control systems, to give an overall In very large buildings, with a high power demand the supply picture of a given centres power and building services plant condi- authority mains intake may well be at high voltage, typically 11000 tion and performance (Allen, 1986). It is suggested that for the volts 50Hz in the U.K., and in many cases the sub-station for the future these facilities will become an inherent feature of any system transformer and its associated switchgear will be located on the to ensure the most efficient use of technical and financial resources. premises in purpose built accommodation. Such accommodation must comply with the stringent regulations for such equipment set down by the supply and planning authorities, and will incorporate Maintenance and costs appropriate automatically operated fire extinguishing plant such as CO systems. These systems will be subject to specific permit to Increasingly, prudent asset management will include data extracted work maintenance arrangements and regulations, conducted by from plant performance records which can be used to enhance properly trained and authorised engineering personnel (Carter, Building engineering services 24/15 1979). The regulations for high voltage systems used in buildings housing communications plant are not specific to them but are Table 24.1 A.C. power plant reliability covered by the details set down, in the U.K. at least, by legislation Type of MTBF of Engine A.C. system embedded in the Electricity Factories Acts and Electricity Supply supply and mains supply failure to MTBF of Regulations (IEE),