"UL Standard for Safety Electrical Apparatus for Explosive Gas Atmospheres – Part 18: Construction@ Test and Marking of Type of Protection Encapsulation ""m"" Electrical Apparatus (Second Edition)"
This?standard gives the specific requirements for the construction@ testing and marking of electrical apparatus@ parts of electrical apparatus and Ex components with the type of protection encapsulation ??m??. This?standard only applies for encapsulated electrical apparatus@ encapsulated parts of electrical apparatus and encapsulated Ex components (hereinafter always referred to as ??m?? apparatus) where the rated voltage does not exceed 10 kV with a relative tolerance of +10 %. This standard supplements the general requirements in?UL 60079-0. The U.S. version of IEC 60079-18 does not include requirements for Group I electrical apparatus. Where references are made to other IEC standards@ the referenced requirements found in these standards shall apply as modified by any applicable U.S. National Differences.