Secondary power supplies must provide power to a fire alarm system for a minimum of how many hours?

The requirement for secondary power supplies in fire alarm systems is crucial for ensuring their reliable operation during emergencies. A minimum duration of 24 hours of power supply is mandated to allow the system to remain functional in case of a primary power failure. This duration is based on the expectation that, during a fire event, it may take time for responders to handle the situation, and vital systems must remain operational throughout this period.

By providing power for at least 24 hours, fire alarm systems can continue to monitor for any signs of fire and maintain alarm activities, thereby enhancing safety for occupants. This requirement is in line with industry standards and codes which emphasize the need for maintaining alarm functionality even when standard power supplies are interrupted.