Which fire alarm stage involves a two-step activation process?

• A. Single stage
• B. Three stage
• C. Quad stage
• D. Two stage

Answer: (D)

Two-stage fire alarm systems require a two-step activation to balance prompt warning with reducing false alarms. In the first stage, a detected event triggers a local alert or partial alarm, notifying occupants nearby and allowing staff to assess the situation. If the event is confirmed or continues, the system escalates to the second stage, sounding the full building alarm and activating all life-safety measures (evacuation announcements, elevator recall, coordination with responders). This approach is common in larger facilities to prevent unnecessary evacuations from brief or benign incidents while ensuring immediate, full alert when real danger is present.