When the main power is disconnected, how long should a power supply with emergency voice...

Emergency voice/alarm communication systems must continue functioning after a loss of primary power for aminimum of 24 hours in standby, followed by15 minutes of alarmoperation.

NFPA 72 (2022), Section 10.6.7.2.1.1 (Exception):

“…followed by 15 minutes of alarm for emergency voice/alarm communication systems.”

This ensures that occupants can still hear evacuation messages even during a power outage.

Correct answer: D. Minimum of 15 minutes

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