Why Do You Need a Short Circuit, Coordination, and Arc Flash Study?

A short circuit and coordination study is critical for the safe, efficient, and economical operation of any electrical distribution system. A short circuit study will help to ensure that personnel and equipment are protected by establishing proper interrupting ratings of protective devices (circuit breaker and fuses). If an electrical fault exceeds the interrupting rating of the protective device, the consequences can be devastating, including injury, damaged electrical equipment, and costly downtime.

A coordination study maximizes power system selectivity by isolating faults to the nearest protective device, as well as helping to avoid nuisance operations that are due to transformer inrush or motor starting operations.

A short circuit and coordination study is a very important, yet sometimes an overlooked step after the initial design and before the implementation of an electrical distribution system. The NEC addresses the importance of this type of study in articles 110-9, 110-10, 240, and 517.17. It is clear that a third party, independent study performed during/after the equipment submittal process, can prove to be invaluable.

A short circuit and coordination study serves to incorporate all the system changes that come about after the initial design. Some examples of factors that commonly change in the implementation of a system are: the utility available fault level, size and/or transformer impedance values, conductor size/type, addition of motors, and the system operating parameters.

Here’s a sample SSCAF report:  Sample SCCS with AF Report