Where required, survivability means that fire alarm circuits must operate for not less than?

• A. 1 hour
• B. 2 hours
• C. 3 hours
• D. 4 hours

Answer: (B)

Survivability means the fire alarm system must keep operating during a fire or power loss for a minimum period so occupants can be warned and responders can work effectively. This reliability is achieved by providing standby power sources, such as battery backup and independent power paths, so the critical circuits stay energized even if the main power fails. The standard minimum duration is not less than two hours, ensuring evacuation signaling and system operation can continue through the early, most critical phase of an incident. A shorter duration like one hour wouldn’t give enough time for safe evacuation and initial firefighting actions, while durations of three or four hours are not the usual baseline requirement except in special cases.