The term “working distance” appears 20 times in the 2012 Edition
of NFPA 70E, the Standard for Electrical Safety in the
Workplace. It appears 12 more times in the annexes. The working
distance is an important component of the arc flash hazard
analysis and is frequently listed on arc flash warning labels
and in the arc flash report. IEEE 1584—IEEE Guide for Performing
Arc Flash Hazard Calculations 2002 defines the working distance
as “the dimension between the possible arc point and the head
and body of the worker positioned in place to perform the
assigned task.” When incident energy is calculated as part of an
analysis, it corresponds to a specific distance from the
prospective arc flash source, making the working distance a very
important piece of information. If a person is located closer
than the working distance, the incident energy increases
dramatically. The table above illustrates how incident energy
varies with distance. Calculations were performed for distances
ranging from 6 to 36 inches for a 480-