Under maximum quiescent load, the secondary power supply shall have sufficient capacity to operate an electronic premise security system for at least how long?

• A. Two hours
• B. A minimum of 4hrs
• C. Eight hours
• D. Six hours

Answer: (B)

The main idea here is how long a backup power source must keep the security system running during a power outage, using the worst-case idle power draw. Quiescent load is the system’s standby current when it’s powered but not actively triggering alarms. The maximum quiescent load means you assume the highest possible idle demand across the system while it remains ready to respond.

The backup secondary power supply must be sized to sustain operation for a minimum period under that worst-case idle draw, so the system remains functional for monitoring, communication, and notification during an outage. Four hours is the standard minimum duration, balancing reliability with practical battery size and cost. Shorter backups (like two hours) risk losing functionality before power is restored, while longer durations (eight or six hours) exceed the typical minimum requirement unless a specific installation calls for it.