The EN 54-4 power supply equipment may have its own cabinet, or may be housed with other equipment of the fire detection and fire alarm system, such as the control and indicating equipment of EN 54-2 of EN 54-16. A fire detection and fire alarm system may use more than one power supply equipment.
There shall be at least two power sources for the power supply of a fire detection and fire alarm system; the main power source and the standby power source. At least one standby power source shall be a rechargeable battery. The power supply equipment shall include charging equipment to charge the battery and maintain it in a fully charged state.
Each power source, on its own, shall be capable of operating those parts of the fire detection and fire alarm system for which it is intended.