What are the secondary power supply requirements for a household alarm system?

The secondary power supply requirements for a household alarm system are designed to ensure that the system remains operational during power outages and functions effectively when triggered by an alarm condition. The requirement for 24 hours of normal operation means that the backup power source must be able to support the system's power needs for an entire day without relying on external power. This is crucial because power outages can last longer than anticipated, and having a full day of backup ensures continuous protection.

The additional specification of 4 minutes in alarm refers to the system's ability to remain powered when an alarm is activated. This is important because during an alarm event, the system may require more power due to the activation of sirens, notifications, or communication with monitoring services. Four minutes provides a meaningful buffer for the alarm to notify occupants or the monitoring center before the backup power could potentially deplete.

This combination of operational needs embodies a practical approach to ensuring the reliability and effectiveness of the alarm system under various conditions.