OSHA does not consider cotton clothing protective against electrical arcs
From OSHA’sfinal rule for electric power generation, transmission and distribution
Untreated cotton can ignite and continue to burn when subjected to incident heat energy above its ignition threshold (Tr. 467-469, 472). OSHA does not consider cotton clothing, which can ignite and pose a hazard itself, as constituting protective clothing with respect to electric arcs common to work covered by the final rule.