Arc Flash in the NEC: Articles 240.87, 240.67; intent reality, does the code achieve its goals? Do you achieve its goals?

摘要

The NEC has included requirements for Arc Flash related labeling for several code cycles. Increasingly rigorous requirements for specific arc flash related protection attempt to reduce the arc flash hazard personnel may be exposed to during the life of the installation. Personnel may be exposed during planned energized work, or accidentally at any time. The risk control mechanisms added into the NEC include additional signage requirements and two articles that intend to reduce the arc flash hazard by decreasing clearing time for circuits rated ≥ 1200 A whether protected by circuit breakers or fuses. This article shall discuss these recent added protection requirements, their intent and their potential practical effects, as well as how to ensure the intended protection this language seeks to provide is truly included in the electrical power distribution system.