This equipment needs to be installed in accordance with latest NEC. Code updates have focused on ways to reduce the energy released during an electrical arc fault.

Here’s a brief and recent history of NEC changes related to reducing arc energy:

2011: NEC Section 240.87
Section added to address situations where circuit breakers are used without instantaneous protection and provided allowable methods to reduce arc energy. Three acceptable methods to mitigate this risk included zone selective interlocking, differential relaying, and energy reducing maintenance switches.

2014: NEC Section 240.87 (updated)
Expanded the requirements to include all circuit breakers that are rated (or could be adjusted to) 1200 A and above. Also added two new mitigation methods which included an energy reducing arc flash mitigation system or approved equivalent means.

2017: NEC Section 240.67
Arc energy reduction requirements of 240.87 were expanded to include fuses rated 1200 A or more are installed. It also added two additional methods in circuit breaker applications which included instantaneous settings.