motion

Motion sensors trigger on a moving heat source and switch off once movement stops, unlike continuous-presence radar.

They suit transient traffic such as stairwells, corridors and outdoor lighting, where a short on-time is wanted. Detection angle, range in metres and lux threshold are the main specs.

• Angle & range — wide-angle PIR (up to ~120°) suits corridors, narrow beam suits driveways
• Lux threshold — a light sensor disables triggering in daylight to save energy
• Timer — adjustable hold time sets how long the load stays on after movement