ABSTRACT
There are rare occasions when the public electricity supply fails and a building is left without electricity. In some buildings, the risk of being totally without electricity cannot be taken, and some provision must be made for an alternative supply to be used in an emergency. What form this provision should take is an economic matter which depends on the magnitude of the risk of failure and the seriousness of the consequences of failure. In this chapter, we shall say something about the available methods of providing an alternative supply.
