Personal Protective Equipment (PPE)
Categories of PPE as described in NFPA 70E are:
Category Cal/cm2 Clothing
0 1.2 Untreated Cotton.
1 5 Flame retardant (FR) shirt and FR pants.
2 8 Cotton underwear FR shirt and FR pants.
3 25 Cotton underwear FR shirt, FR pants and FR coveralls.
4 40+ Cotton underwear FR shirt, FR pants and double layer switching coat and pants.
WHAT DOES HRC MEAN??
Hazard/Risk Category or HRC is a term used within the current NFPA 70E and CSA Z462 Electrical Safety standards. It is used to describe both the arc flash hazard and arc-rated PPE requirements. The HRC attempts to describe the potential thermal energy of an arc incident, to which the user would be exposed, and the risk or probability of the incident occurring. A hazard analysis must be conducted prior to performing a task on or near an energized system, to determine the extent or level of the hazard. In some cases, the risk of an arc flash occurring is as low as reasonably practical and no arc flash PPE is required. In other cases, that risk and resulting thermal energy may be substantial. This can only be determined by an engineering incident energy hazard analysis.
NFPA 70E and Canada’s CSA Z462 reference 5 different hazard risk categories, from “0” (no arc-rated protection) to 4. The higher the number, the greater the protection. With this value known, one can select protective gear suitable against that level of hazard. Simply put, it is important that the level of protection(arc rating) of the arc flash protective gear one is wearing must be AT A MINIMUM equivalent to the thermal energy created by the arc flash incident. If the hazard is greater, the probability for injury or death resulting from burns increases. When selecting the arc flash PPE, the insulating capability of the garment system must be greater than or equal to the higher value of that category.
A last point . . . Hazard/Risk Categories are only relevant if you are using the task tables within the standards as your hazard analysis tool. If you are using other means such as the IEEE 1584 to calculate your potential energy level, then you can simply compare the Arc Rating (ATPV or EBT) detailed in the label of the garment to select a garment system that offers protection in excess of your calculated energy levels.
However, as you are reading this, all of this terminology will be changing with the release of the next version of NFPA 70E and CSA Z462 later this year and early next year. The terminology will be replaced with PPE Categories and PPE Levels, which will more appropriately and more specifically describe the protection offered by the PPE, rather than referring to the level and probability of an arc incident’s hazard level.
Since the electrical arc hazards of the world do not stop at 40 calories, Oberon created the additional Categories to assist your users to more clearly understand the protective levels offered by the garments. The “ORC” were created to compliment the HRC levels. You will not find them detailed in the safety standards, however, they are consistent with the mandate that the protection you wear must provide a higher level of insulating protection than the hazard to which you are exposed.