A fire alarm's backup battery must have the capacity to sound the alarm for how long?

• A. 1 minute
• B. 5 minutes
• C. 10 minutes
• D. 15 minutes

Answer: (B)

The main idea here is how long a fire alarm’s backup power must keep the audible devices sounding after the main power fails. The backup battery is sized to ensure the system can produce audible notification for a defined period during an outage, so occupants have time to hear the alarm and evacuate. That required duration is five minutes of continuous alarm operation. So five minutes is the correct choice because it represents the minimum amount of time the backup power must sustain the audible notification, even when the main power is out. (Note: standby power requirements for the system as a whole are broader, but this question is about the duration the alarm must sound on backup power.)