Final answer:
Secondary power supplies for fire alarm systems must maintain the system in standby mode for 24 hours and support alarm conditions for an additional 5 or 15 minutes depending on the system's features, according to NFPA standards.
Step-by-step explanation:
Fire alarm systems are critical safety components in buildings, designed to alert occupants in the event of a fire. They are required to have secondary power supplies that can sustain the alarm system during power outages. According to the National Fire Protection Association (NFPA), these secondary power supplies must be capable of operating the fire alarm system in a standby (quiescent) state for a minimum duration. This requirement ensures that even in the event of a power failure, the system will remain active and able to respond to a fire condition.
The secondary power supplies must operate the system in standby mode for 24 hours, followed by a full set of alarm conditions for 5 minutes if it's a voice-evacuation system, or 15 minutes for other systems without voice-evacuation features. This is the minimum performance requirement, and it is quite common to have systems designed for longer standby durations.