This chapter reviews the six basic configurations and aims to compare how the arrangement of switching devices and buses of each impacts reliability and these parameters. These are single bus, double bus–double breaker, main and transfer bus, double bus–single breaker, ring bus and breaker-and-a-half. Various factors affect the reliability of an electrical substation or switchyard facility, one of which is the arrangement of switching devices and buses. Cost of a single bus arrangement is relatively low, but also is the operational flexibility; for example, transfer of loads from one circuit to another would require additional switching devices outside the substation. The main and transfer bus configuration connects all circuits between the main bus and a transfer bus. Maintenance as well is facilitated by the arrangement, since an entire bus and adjacent breakers can be maintained without transferring or dropping loads.