PIR Occupancy Sensor

Square D PIR sensor

One type of occupancy sensor uses passive infrared, or PIR, technology to detect motion. The term passive means that the PIR device does not emit an infrared beam but merely passively accepts incoming infrared radiation. Infra means below a human's ability to detect it visually, and Red because red represents the lowest energy level that our eyes can sense before it becomes invisible. Therefore, infrared means below the energy level of the color red, and applies to many sources of invisible energy.

Motion is detected when an infrared source with one temperature, such as an occupant, passes in front of an infrared source with another temperature, such as a wall. The heat of the passing occupant isn't detected by the sensor, but rather the "normal" state of the sensor field is broken. Even objects exactly the same temperature as the "normal" state of the sensor will cause the PIR to activate if it moves within the field of the sensor.

Contact a Graybar Lighting Consultant to learn more about PIR occupancy sensors offered through Graybar.