BS EN 50171:2021

This document specifies the general requirements for central power supply systems for an independent energy supply to essential safety equipment. This document covers systems that are permanently connected to AC supply voltages not exceeding 1 000 V and use batteries as an alternative power source. Central safety power supply systems are intended to ensure energy supply to emergency escape lighting in the event of normal supply failure and could be suitable for energizing other essential safety equipment, for example: - electric circuits of automatic fire extinguishing installations; - paging systems and signalling safety installations; - smoke extraction equipment; - carbon monoxide warning systems; - special safety installations related to specific buildings, e.g. high-risk areas. The power supply of CPS systems is expected to be dedicated only to the essential safety equipment, and not for other type of loads such as general purpose IT or industrial systems etc. Combinations of the aforementioned safety equipment types can be used together on the same central safety power supply system providing the availability for safety equipment loads is not impaired. A fault occurring in a circuit is expected to not cause the interruption in any other circuit used to supply essential safety equipment. Schematic representations of typical central safety power supply equipment are depicted in Clause 4. Power supply systems for fire alarm equipment that are covered by EN 54 (series) are excluded.