The standard for electrical safety in the workplace (NFPA 70e) has developed a matrix of
Hazard/Risk Categories (HRC) to help match the tasks being performed on energized electrical equipment to the appropriate flame resistant protective clothing. While garments with a higher arc rating can be used; a garment's specific minimum for arc ratings required by Hazard/Risk Categories should be followed.
See HRC Arc Ratings below.
Hazardous Risk Categories
The garments in:
HRC 1 have Arc Ratings between 4 cal/cm2 and 7.9 cal/cm2.
HRC 2 have Arc Ratings between 8 cal/cm2 and 24 cal/cm2.
HRC 3 have Arc Ratings between 25 cal/cm2 and 39 cal/cm2.