Full definition
Garments rated with an ATPV (Arc Thermal Performance Value) in cal/cm² that protect against burn injuries from arc flash events. NFPA 70E PPE categories: Cat. 1 (≥4 cal/cm²), Cat. 2 (≥8), Cat. 3 (≥25), Cat. 4 (≥40). Materials: Nomex® IIIA, Protera®, FR-treated cotton. Never use synthetic fabrics without arc rating — they melt onto skin. Arc hazard analysis (IEEE 1584) determines required category for each piece of equipment.