A practical approach to arc flash hazard analysis and reduction

Recent efforts to quantify the dangers associated with potential arc flash hazards rely on overcurrent protection to remove a given fault condition. The effectiveness of various devices is determined by a clearing time related to the maximum available fault current for each system location. As industrial and commercial facilities begin to embrace arc flash labeling procedures and begin to recognize arc flash prevention as a part of a complete safety program, the current method of calculation will allow them to quantify the incident energy (cal/cm²) associated with a maximum three-phase fault condition. Most faults produce current magnitudes less than the three-phase maximum. This paper will consider fault current magnitudes less than that of the maximum three-phase condition, and discuss the resulting calculations for incident energy across the range of current magnitudes. Under these additional scenarios, the performance of various overcurrent protection devices will be demonstrated. Associated considerations for design, modeling, and maintenance will be presented.