Electrical apparatus enclosures for use in flammable or explosive gases or vapours. Design and construction, tables the grouping of gases and vapours and the corresponding permissible gap dimensions for flanged joints. Treatment of control spindles, shafts, conductors, etc. Appendices detail requirements for certification as flameproof. (See also BS 5501-5).Replaced by BS 4683-2:1971, but remains current to allow for existing certification.