Which of the following best describes a recommended practice for mounting motion detectors in UL burglar alarm systems?

• A. They should be arranged to avoid false alarms caused by outside movement in an unprotected area
• B. They should be mounted near vents
• C. They should be placed behind curtains
• D. They should be installed at floor level

Answer: (A)

The key idea is placing motion detectors so they focus on the protected interior and avoid triggers from movement outside that area. Motion detectors respond to motion and heat in their field of view, so mounting them to ignore outside movement in unprotected zones helps prevent nuisance alarms while still catching actual intrusions. Placing a detector near vents can cause false alarms from air drafts, putting it behind curtains can block or dampen the sensing area, and installing it at floor level generally reduces the detector’s effectiveness since it’s designed to sense movement at typical adult heights. For reliable protection with few false alarms, mount the detectors to cover interior protected spaces and minimize exposure to outside movement.