This standard applies to Automatic Transfer Switching Equipment (ATSE) to be used in emergency power systems with interruption of the supply to the load during transfer, the rated voltage of which does not exceed 1 000 V a.c. or 1 500 V d.c. It covers ATSE provided with or without an enclosure.Devices necessary for the control (e.g. control switches, ...) and the protection (e.g. circuit-breakers, ...) of an ATSE shall comply with the requirements of the relevant IEC standards.ATSE used only for emergency lighting may be subject to specific rules and/or legal requirements and are not, therefore, covered by this standard.