Which device is used for an interior following zone to detect movement?

• A. Smoke detector
• B. Heat detector
• C. Glass-break detector
• D. Motion detector

Answer: (D)

Detecting movement inside a protected area requires a motion detector. These sensors are designed to sense changes caused by a living body moving through the room, typically using passive infrared (PIR) technology or other methods like microwave. They are placed in interior zones so the system can trigger as soon as movement is detected, even if doors and windows aren’t being opened.

Smoke detectors look for smoke and indicate fire, not movement. Heat detectors respond to rapid temperature changes or high heat, not motion. Glass-break detectors listen for the sound or vibration of breaking glass, which is related to an event at the window, not movement within the interior space.