Codes and Standards

NEC 240.67 Arc-Energy Reduction (Technical Paper)

NEC 240.67 arc flash reduction technical paper

Arc energy reduction is critical for electrical safety in the workplace. NEC 2011 introduced an Arc Energy Reduction requirement for circuit breakers (NEC 240.87) rated 1200 A and higher. The added circuit breaker requirement has reduced arc-flash injuries since being introduced by lowering fault clearing times. The value of 0.07 s for the new fuse clearing time requirement was chosen to align with circuit breakers using zone selective interlocking.