Duration of Standby Supplies
Is the supply period of the backup battery you install suitable for the system type and the level of supervision?
Compliant with BS 5839 – for Category M (manual fire systems with no auto fire detection) or Category L (automatic fire detection systems designed for the protection of life) systems, the battery standby capacity should be sufficient to maintain the system in an operational condition for at least 24 hours after which there should still be an adequate capacity to provide an "evacuate" signal in all alarm zones for a minimum of 30 minutes.
When a Category M or L system is installed in a building with an automatically triggered standby generator supplying the fire alarm system, the battery standby capacity should be sufficient to maintain the system in an operational condition for at least 6 hours. After that, there should still be enough capacity to provide an "evacuate" signal in all alarm zones for a minimum of 30 minutes.
For a Category P system (automatic fire detection systems intended for the protection of property), the battery standby capacity should be sufficient to maintain the system in an operational condition for at least 24 hours, after which there should still be enough capacity to provide an "evacuate" signal in all alarm zones for a minimum of 30 minutes, provided that either of the following conditions is met:
- the building is continuously staffed or inspected outside of regular working hours, and that staff would be aware of a power supply fault indication on the system within 6 hours of its occurrence; or
- power supply fault signals are transmitted automatically to an alarm receiving centre (ARC), and the ARC notifies a keyholder on receipt of a fault indication from the protected premises.
Suppose neither of the above requirements is met, then the battery standby capacity should be sufficient to maintain the system in an operational condition for at least 24 hours longer than the maximum period the premises is likely to be unoccupied or for 72 hours in total, whichever is less. After which, there should still be sufficient capacity to provide an "Evacuate" signal in all alarm zones for a minimum of 30 minutes.
Preventing Fire Alarm Backup Battery Failure
The most important step is to perform the required annual fire alarm backup battery test and check with the authority having jurisdiction to see if additional testing is needed. Perform testing more frequently on regularly used ageing batteries. Additionally, simply checking up on the fire alarm system. If the fire alarm battery light is on, there’s a problem. Power outages happen when there’s bad weather. Help protect your clients' facilities by testing fire alarm system backup batteries annually and taking a few precautionary steps.
