While this design guide applies to all types of power generating stations, it is particularly applicable to stations in which the electric power service system is required to perform continuously. When electric power for auxiliary loads is supplied from the power grid, the service system begins at the point where the tap from the power grid terminates, either at a station service bus or at the terminals of the transformer that supplies the bus. When service to auxiliary loads is from independent generators or electric storage batteries that are not normally operated as power supplies to the power grid, the station service system includes the generators and storage batteries. The service system includes all of the electric power using devices it serves, such as motors, resistance heaters, rectifiers, etc. This guide contains a listing of typical power plant auxiliary loads and criteria for their power service and examples of single-line diagrams for a typical plant. It also includes tables of typical power service parameters to illustrate the range of typical values for each parameter, and it identifies the approximate effect of theminimum and maximum value of each parameter on the load. Each clause, as appropriate, has a bibliography of U.S. industry codes and standards and other reference documents that provide detailed guidance in the design and specification of station service system components.