For an in-building fire emergency voice/alarm communication system, how long should the secondary power supply last during an alarm?

The duration for the secondary power supply in an in-building fire emergency voice/alarm communication system is critical for ensuring safety during an emergency evacuation. The correct answer is that the secondary power supply should last for 15 minutes during an alarm.

This requirement is based on the understanding that emergencies can vary in duration, and it's vital for communication systems to remain operational long enough for effective alerts and directions to be provided to building occupants. A 15-minute timeframe allows sufficient time for occupants to be alerted and begin evacuating the building safely, as well as giving first responders enough time to assess the situation upon arrival.

While options such as 5, 10, or 30 minutes may seem relevant, they do not align with the standard requirements for fire alarm systems. A 5-minute duration may not adequately cover the time needed for evacuation in larger facilities, while 30 minutes could be excessive for typical emergency scenarios and may not be practical given the battery life and maintenance considerations for such systems. Thus, 15 minutes is a standard industry practice ensuring both safety and practicality.