Intelligent Power Today Magazine

IEEE Method Vs. the NFPA 70E Tables: Evaluating arc flash analysis methods

BY REZA TAJALI, Schneider Electric

Recent changes in workplace safety regulations have heightened the awareness of hazards associated with electrical arcs. The hazard level must be quantified and workers properly protected before entering proximity of exposed energized conductors. National Fire Protection Association’s (NFPA) standard 70E: “Standard for Electrical Safety in the Workplace” provides the guidelines for work involving electrical hazards and the selection of arc flash protective equipment.

In order to select the protective gear properly, one must have knowledge of the potential thermal energy of the electric...

I recently viewed a destroyed 600-volt electrical panel board that had exploded when an operator reset an 800-ampere (A) breaker. His leather-palmed gloves had synthetic backs that ignited and seriously burned the back of his hands. His flame-resistant (FR) shirt was untucked and he was burned on his right side.

It is unfortunate that he was not following Canadian Standards Association’s CSA Z462 standard: “Workplace Electrical Safety” clause 4.3.7.3.10 (d). It is incredibly fortunate that his employer provided arc-rated clothing, as only a few years ago, he would have been wearing cotton coveralls.

Consequently, this incident would have resulted...