Arc Flash Category 4 and 4+ ? Eleceng01 (Electrical) (OP) 22 Jun 07 13:05. I was hoping to get everyones help on this. I see that several manufacturers offer arc suits up to 100 cal/cm^2 but my understanding of the NFPA70-2004, Table 130.70(c)(11) is that anything above 40 cal/cm^2 can not be worked on energized.