The electrical engineer is responsible for distributing power from the service entrance to its varied destinations throughout the facility. This chapter introduces some of the equipment that the engineer must size and specify when designing a safe and efficient power distribution system. It presents the motor control center layout as well as circuit breaker selection considerations. One of the most important ratings for a circuit breaker is its ability to interrupt a short circuit. The chapter summarizes breaker and starter sizes for motor control centers. It also summarizes dual-element fuse and switch sizes for motor control centers. There are several types of fuses commonly used. Each type is characterized by its time to isolate the fault, interrupting rating, and current limiting property. Fuse types include standard fuses, dual element fuses, limiters, fast-acting fuses, and semiconductor fuses. Circuit breakers and fuses are used to protect wiring and equipment from fault currents.