Two Case Histories: Two Outcomes

摘要

Comparison of two case histories helps illustrate the benefits of assessing an arc flash hazard mitigation program. The first incident involved six injuries, including two bystanders and four electricians who were wearing arc-resistant protective clothing rated for the task, but underrated for the amount of energy available at the work location. The task involved racking 480 V draw out circuit breakers on and off the substation bus. Full-body protection rated at 20 calories/cm~2 was being worn. An unsecured metal plate used to cover an opening in the circuit breaker compartment door fell, contacted the exposed bus and created an arcing fault. Six people were transported to the hospital, including the four electricians and two supervisors who were observing the work activity from a distance.