OSHA released this interpretation in March of 2010. This lets you know when you must and when you may use flame resistant clothing. I’ve put this in the Interpretations under electrical safety because there is so much overlap in the hazards. Arc rated clothing meeting ASTM F1506 will usually meet NFPA 2112 but few materials are tested to this standard because of requirements for certification. ASTM standards are usually third party tested and internally tested but some NFPA standards require certification and there is little competition for certification and the process is costly.