IEC 60079-18 Ed. 2.0 b:2004

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””. Only applies for encapsulated electrical apparatus, encapsulated parts of electrical apparatus and encapsulated Ex components (“”m”” apparatus) where the rated voltage does not exceed 10 kV with a relative tolerance of +10 %.