Specifies requirements for high voltage a.c. switchgear assemblies, indoor and outdoor, employed in connection with the generation, transmission and distribution of electric power and to ancillary equipment used in conjunction with the switchgear. Gives detailed requirements for electrical clearances, safety of personnel, earthing of main circuits, substations and their enclosures. Also specifies requirements for busbars, marking and identification of conductors and terminals, colours of indicator lights, and electrical and compressed air auxiliary systems. Appendices include jointing of busbars and connections, design of earthing systems, and provision of safety clearances.