This part of IEC 60079 specifies the requirements for the construction and testing of oil-immersed electrical equipment, oil-immersed parts of electrical equipment and Ex components in the type of protection oil immersion "o", intended for use in explosive gas atmospheres. The significant changes with respect to the previous edition are: all requirements for third-party certification removed; added requirements for external connections; collected all marking requirements in the marking clause, and added requirements for instructions.