During an emergency, how long should the secondary power supply for an in-building mass notification system last?

The duration of the secondary power supply for an in-building mass notification system is critical for ensuring that the system remains operational during an emergency when primary power sources may fail. The specified duration of 15 minutes is aligned with the National Fire Protection Association (NFPA) guidelines, specifically NFPA 72, which governs the performance and reliability of fire alarm and signaling systems.

In emergency situations, it is vital that notification systems can provide effective alerts to occupants in a timely manner. A 15-minute requirement is considered a sufficient period to ensure that alerts can be communicated effectively until primary power can be restored or personnel can be safely evacuated. This timeframe acknowledges potential variances in emergency response times and the necessity for the notification system to remain functional under such conditions.

Other durations, such as 5 minutes, would not allow enough time for effective communication in emergencies, while 30 minutes or 1 hour might be excessive for most typical scenarios, potentially increasing costs and complexity without additional benefit in most situations. Therefore, 15 minutes represents a balanced and practical standard for the secondary power supply of an in-building mass notification system.