Arc Flash - Arc Flash is a “dangerous condition associated with the release of energy caused by an electrical arc.” (NFPA 70E) The formula to calculate arc flash energy is, EMB = 1038.7 DB exp(-1.4738) × tA [0.0093 F exp(2) 0.3453 F 5.9673] Where: EMB = is the arc flash energy DB = is the working distance (from Table 3 of IEEE 1584) tA = is the duration of the arc, and F is the short-circuit (or fault) current. This equation uses inches for distance measurements, and gives results directly in ca