Applies to all installations with voltages up to and including 1 000 V as well as with those above 1 000 V. Describes protective measures intended to ensure the safety of persons from electric shock in normal service and in case of fault. Also, particular requirements applicable to TN, TT and IT system earthing. Extends the principles to the protection against overcurrent in respect of overload and short-circuit protection, together with the co-ordination of overload and short-circuit protection and the coordination of this protection with the conductors and apparatus. Also, the principles developed in IEC 364 for the protection of conductors are extended to the protection of apparatus in respect of security of the installation and protection of personnel.