Arc flash hazard awareness is a critical topic for those responsible for the management of electrical
power systems.

• NFPA 70E requires an evaluation of the arc flash hazard level at each piece of electrical equipment and a listing of the Personal Protective Equipment (PPE) necessary if the equipment is to be worked on while energized.
• NFPA 70E and IEEE Standard 1584-2002 provide the means of calculating the hazard level in terms of incident energy of the arc.

In the evaluations used in both standards, the hazard level becomes a function of available bolted fault current at the point being evaluated and the time that a fault might be allowed to persist before some portion of the protective system clears the fault. Reducing either the bolted fault current or the clearing time will reduce the arc flash hazard, and a sufficient reduction of the hazard will allow use of less restrictive PPE. The magnitude of the available fault current is dependent on the configuration of the system, the sources available, and other factors beyond the scope of the protective system. The clearing time, on the other hand, is directly controlled by the protective system.

Arc Flash Hazard Mitigation

For details on how the BE1-50/51B-235 and 237 can help meet NESC Arc Flash requirements, see the Plug and Play Feature Flyer.

See Application Note PC-ArcFlash - Arc Flash Hazard Mitigation Through Relaying for tips.

Several opportunities are available to use relays for the mitigation of arc flash hazards. The goal is to achieve fault clearing within 10 cycles, and most of the techniques can provide that clearing time without compromising selectivity.

For more information, see the Technical Paper - Arc Flash Mitigation Through Use Of Voltage Controlled/Voltage Restrained Overcurrent Elements - This paper investigates the use of voltage controlled/voltage restrained overcurrent elements as an arc flash mitigation technique when applied to certain industrial circuits.