Selective Coordination of OCPDs

Selective coordination, defined in Article 100 of the NEC, is the process of coordinating overcurrent protection to localize the impact of an outage, which is accomplished via the selective operation of the device closest to the fault only. Assuming the fault condition in Figure 2, for example, selective coordination ensures that only the 100 A OCPD at location 1 opens and that the OCPDs at locations 2 and 3 remain closed. Generally speaking, PV systems are not subject to the selective coordination requirements in the NEC. The requirements for selective coordination apply specifically to emergency systems (Section 700.32), legally required standby systems (Section 701.27) and critical operation standby systems (Section 708.54).