Selective Coordination

Understanding Selective Coordination and Coordination in the 2014 National Electric Code (NEC)
Selective coordination is not new to the NEC, but the interpretations and enforcement of it have varied. The NEC 2014 clearly defines two distinct levels of coordination; Selective Coordination for all currents and times and Coordination to 0.1 seconds.

Selective coordination is required for systems related to life safety (as defined in the NEC), and is achieved when an overcurrent on a circuit is interrupted and only the closest upstream device opens such that only the section of the electrical system with a problem is taken offline. Selective coordination applies for the full range of overcurrent on the system and the full range of overcurrent interrupting times associated with those overcurrents.

Coordination is required for over current protective devices for Essential Electrical Systems in healthcare facilities. The overcurrent protective devices must be coordinated for any fault time extending beyond 0.1 seconds. Essential Electrical Systems are comprised of life safety branch, critical branch, and equipment branch.