The only thing addressed in OSHA is that employees exposed to the potential of electrical arcs should wear non-melting fibers and specifically bans nylon, rayon, polyester alone or in blends.
However the general PPE section says industry standards should be followed and the NFPA 70E is considered the industry standard so FR clothing is indirectly required to be used by OSHA.
The 70E has been submitted in court by OSHA for violations and they have fined companies for not following the 70E requirements for protection of persons from electric arcs.
