Which feature is essential in a fire alarm control panel?

The essential feature in a fire alarm control panel is a supervisory signal for power failure. This feature is crucial because it ensures that the fire alarm system remains operational at all times. In the event of a power failure, the supervisory signal alerts personnel to the issue, allowing for immediate action to be taken to restore power or switch to backup systems, ensuring the safety of occupants and the effectiveness of the fire alarm system.

While other features like manual activation capability, real-time monitoring of smoke levels, and evacuation direction messages are important for specific functions or responses in a fire emergency, the supervisory signal is fundamental for the overall reliability and functionality of the entire fire alarm system. If the system goes offline due to a power outage, none of these other features would be functional, making the supervisory signal a paramount component of safety.