Failures of Equipment Operating Under Normal Conditions: Arc-Flash Events can Happen during Normal Operation

Informational Note No. 1 for the definition of arc-flash hazard in National Fire Protection Association (NFPA) Standard 70E-2015 states, "Under normal operating conditions, enclosed energized equipment that has been properly installed and maintained is not likely to pose an arc-flash hazard." Table 130.7(C)(15)(A)(a) of the standard instructs that arc-flash personal protective equipment (PPE) is not required for normal operation of a circuit breaker, switch, contactor, or starter if the equipment is properly installed, properly maintained, equipment doors and covers are closed and secured, and there is no evidence of impending failure. This article reviews three electrical equipment failures during substation circuit breaker operations where if personnel had followed the guidelines just described, they could have been seriously injured during these failures due to the arc-flash energy released at the time of the fault.