Understanding Arc Flash PPE Category
Whether to wear arc-rated personal protection equipment (PPE) is not a personal decision. The U.S. Occupational Safety and Health Administration (OSHA) directs employers to supply PPE and for employees to wear the supplied PPE if hazards exist. An arc flash risk assessment can indicate whether such PPE is needed. The analysis also needs to be documented.
PPE is a combination of protective clothing, helmets, goggles, or other garments or equipment to protect eyes, head, breathing, and the full body from splashes, vapors, loose objects, and chemical penetration through personal clothing. The level of protection depends on the level of exposure in the working environment.
Personal Protective Equipment categories
The National Fire Protection Association (NFPA) uses four Arc Flash PPE Categories to classify ranges of arc flash hazards, and the corresponding requirements for PPE. The categories are one of the methods used in the current NFPA 70E standard to inform workers about the protection they need while working on energized equipment. CSA Z462 recently added an Arc Flash PPE Category 5 for equipment with potential incident energy levels up to 75 cal/cm2.
Each category includes a minimum arc rating value for the required PPE. This value is determined by the PPE manufacturer, and indicates the protection provided by the equipment (in cal/cm2) as the point where a worker would have a 50% probability of receiving a 2nd degree skin burn.
Always abide by the limits of use and minimum working distance. The following PPE categories are described by the National Fire Protection Association (NFPA) Standard 70E. The greater the electrical hazard, the higher the personal protective equipment arc rating must be to withstand an arc-flash incident. Please note that the following chart is a summary only. For a complete list of NFPA standards see NFPA 70E Table 130.7( C)(16)