Occupancy motion sensors sense movement in the room and turn the lights on. After a period of time with no movement detected, often 30 minutes, it shuts the lights off.
A ceiling mount motion detector mounts on or near the ceiling and faces downward. Many ceiling mount motion detectors offer a 360-degree coverage area to sense movement in almost every part of the room.
Motion sensors work well in rooms where the light often gets left on, like corridors, bathrooms, conference rooms, living rooms, and much more.
Ceiling mount motion sensors can install in out-of-the-way ceiling locations, including recessed, wall, and corner options. How high to mount them can depend on the sensor, but, generally, the mounting height of a ceiling motion sensor or ceiling occupancy sensor should remain around 8 - 12 feet. They may mount higher but installing them too high prevents the sensor from detecting movement in some areas.
HomElectrical carries a selection of ceiling mount motion and occupancy sensors, including:
Passive Infrared (PIR) sensors register a person's movement based on their body heat. PIR motion detection requires a strict line of sight to register this movement and turn on the lights. These sensors work well in open areas with few obstacles to block the sensor's path.
Ultrasonic sensors send out ultrasonic waves, measuring the speed at which these waves return to detect a presence in the room. Unlike PIR sensors, ultrasonic sensors do not require a direct line of sight. They can sense a person's movements even behind an obstacle.
Certain sensors combine sensor types, like PIR and ultrasonic technologies, into a dual technology sensor in an effort to reduce false triggers. Additionally, some may come equipped with a daylight sensor to automatically turn the lights on when the level of daylight drops.