The electrical industry has adopted the NFPA 70E standard HRC rating system. The rating system determines the protection standards required for electrical workers at a jobsite. HRC stands for Hazard Risk Category. It is governed by a number scale ranging from 1 to 4, with HRC 1 representing the least danger, and HRC 4, the most danger. HRC levels for FR clothing are determined by the minimum amount of calories per square centimeter (ATPV or Cal/cm2) a flame resistant garment must pass through to create a 50% probability of a 2nd or 3rd degree burn occurring. Safety Supply America offers flame resistant clothing that meets the standards of all HRC levels, from the least hazardous HRC 1 to the most hazardous HRC 4.