Technical Foundation
What Is a PIR Motion Sensor?
A passive infrared (PIR) sensor detects motion by sensing changes in infrared radiation (heat) within its field of view — as a warm body moves across the sensor's segmented detection zones, the resulting change in infrared signal triggers the output. Because it's passive (it doesn't emit any energy, only detects it), PIR is energy-efficient and widely used for lighting control and security applications, though its detection pattern and range are shaped by the sensor's lens design and must be matched to the room geometry and mounting height.
Detection range and coverage pattern (a wide-angle ceiling sensor for open rooms vs. a narrow, long-throw corridor lens for hallways) must suit the physical space, and mounting height affects both range and the sensor's ability to detect motion versus simply detecting a stationary warm body walking directly at it. Dual-technology sensors combine PIR with microwave or ultrasonic detection, requiring both technologies to agree before triggering, which reduces false triggers in spaces with HVAC airflow or reflective surfaces that can fool PIR alone.
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| Spec | What It Means | Why It Matters |
|---|---|---|
| Detection Range | Commonly 15-40+ ft depending on lens design | Must be matched to actual room dimensions and mounting height for full, reliable coverage |
| Coverage Pattern | Wide-angle (room), corridor/aisle (narrow long throw) | Lens pattern must match the physical space shape — a wide-angle lens in a long corridor leaves gaps |
| Mounting Type | Ceiling, wall, corner-mount | Mounting height and angle affect both range and reliability of motion detection versus false triggers |
| Output Type | Relay contact, 0-10V dimming, low-voltage switching | Must match the connected lighting control panel or security system input requirements |
| Environmental Rating | Indoor, outdoor/weatherproof (IP-rated) | Outdoor sensors need weatherproofing and are often less sensitive to avoid false triggers from wind-blown debris |
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Applications
Where PIR Motion Sensors Get Used
PIR motion sensors are specified anywhere automatic lighting control or motion-based security detection is needed without requiring active user input.
Commercial Lighting Control
PIR sensors used to automatically switch or dim lighting in offices, restrooms and common areas based on occupancy.
Warehousing & Industrial Facilities
Sensors used for aisle and high-bay lighting control, reducing energy use in intermittently occupied areas.
Security & Intrusion Detection Systems
PIR sensors integrated into alarm systems to detect unauthorized motion in protected areas.
Outdoor & Perimeter Lighting
Weatherproof PIR sensors used to trigger security and area lighting based on approaching motion.
Parking Garages & Stairwells
PIR sensors used for energy-code-compliant lighting control in intermittently occupied spaces.
Retail & Hospitality Facilities
Sensors used for automatic lighting control in storage rooms, back-of-house areas and restrooms.
FAQ
PIR Motion Sensors Questions, Answered
What's the difference between a wide-angle and corridor-pattern PIR sensor?
A wide-angle sensor is designed for open rooms, casting a broad detection pattern outward from a ceiling or wall mount. A corridor (aisle) pattern sensor instead uses a narrow, elongated lens designed to detect motion along the length of a hallway or warehouse aisle — using a wide-angle sensor in a long corridor typically leaves detection gaps at the far end.
Why does my PIR sensor sometimes fail to detect someone who isn't moving much?
PIR sensors detect changes in infrared signal as a warm body crosses between the lens's segmented detection zones — someone sitting very still, or moving directly toward the sensor along a single zone boundary, can generate less signal change and occasionally go undetected. This is a known limitation of PIR technology, which dual-technology sensors help address by adding a second detection method.
What is a dual-technology sensor and when do I need one?
A dual-technology sensor combines PIR with microwave or ultrasonic detection, and typically requires both technologies to sense motion before triggering (or uses one to confirm the other). This significantly reduces false triggers in environments with HVAC airflow, moving shadows, or reflective surfaces that can fool a PIR-only sensor, at a higher cost than a PIR-only unit.
How does mounting height affect PIR sensor performance?
Mounting height affects both the sensor's effective range and the angle at which it views moving bodies — most sensors specify a recommended mounting height range for their rated coverage pattern, and mounting significantly above or below that range can reduce detection reliability or shrink the effective coverage area.
What output type do I need for lighting control integration?
Match the sensor's output to what your lighting control panel or fixture expects — a simple relay contact output works with basic on/off switching, while 0-10V dimming output is needed if the sensor is meant to control dimmable fixtures as part of an energy-code-compliant lighting control scheme. Confirm compatibility before ordering.
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