Protective Device Coordination Studies

A Protective Device Coordination Study is performed to determine which types of circuit breakers and fuses should be used to minimize unnecessary power outages. Article 240.12(A) of the NYC Electrical Code requires service equipment to selectively coordinate for all disconnects exceeding 601A. The code also requires selective coordination for elevators, emergency, and standby systems.

Protective Device Coordination is performed by plotting Time Current Curves for each overcurrent device. According to the NYC Code, two overcurrent protective devices shall be deemed selectively coordinated if their respective time-current characteristic curves do not intersect at a time of 0.1 seconds or longer. Our studies contain a list of fuse types and a list of settings for the breakers which will allow you to achieve selective coordination and comply with code. The distributor must provide the correct type of fuses to the contractor, and the contractor must ensure that the circuit breaker settings match those in the study.

A contractor does not want to risk installing a system which is prone to nuisance tripping and unnecessary power outages, and a building owner does not want to have tenants complain about loss of power. Therefore, a Protective Device Coordination Study should always be performed to ensure that the correct protective devices are installed.