What is the duration for fire alarm secondary power to maintain the system at normal load?

The duration for fire alarm secondary power to maintain the system at normal load is typically set at 24 hours. This is established to ensure that in the event of a primary power failure, the fire alarm system has enough backup power to continue functioning effectively during critical times, especially in emergency situations.

A 24-hour duration allows for the system to remain operational through potential power outages and ensures that all functions—such as detection, alarm signaling, and system monitoring—are maintained over an extended period, which is crucial for life safety. This duration is in line with standard codes and regulations governing fire alarm systems, reflecting a balance between practical operational needs and the capabilities of battery or secondary power sources.

Shorter durations, like 12 hours, may not provide enough assurance against longer power outages, while longer durations, like 36 or 48 hours, could result in unnecessary costs or complicated system designs that exceed what is generally required for fire alarm operational reliability.