The so-called “arc-in-a-box” has a focusing effect in which radiated energy strikes the back and sides of the box, reflecting out in a higher concentration of energy than would be obtained in open air. As arc current increases, arc voltage decreases. Thevenin Equivalent of System R is found to calculated the short circuit current. Based on the concept that. The method of which to analyze arc flash hazards has evolved through several iterations of NFPA 70E, NPFA 70, and IEEE 1584 standards which modified the calculation methods to provide more accurate data based on testing, as well as UL 2986. (Threepwood) to produce a report about internal arc type testing, arc-flash and how the various issues of switchgear explosions are managed.