What device automatically energizes a lighting circuit?

What device automatically energizes a lighting circuit?

• A. Motion sensor
• B. Timer
• C. Photoelectric switch
• D. Occupancy sensor

Answer: (D)

Automatic energization of a lighting circuit happens when presence in a space is detected. An occupancy sensor is designed to do this: it powers the lights as soon as someone enters and typically turns them off after the space is empty for a set period. This type of sensor can use infrared or ultrasonic methods to detect presence and is commonly adjustable for how long lights stay on after occupancy ends, making it a targeted energy-saving control for spaces that aren’t always occupied. A motion sensor can trigger lights based on movement, but it may not reliably indicate continuous occupancy, and some setups might not energize lights unless movement is detected. A timer follows a fixed schedule and doesn’t respond to whether people are actually in the room. A photoelectric switch uses ambient light levels to decide when to turn lights on or off, which is based on daylight, not people in the space.

Automatic energization of a lighting circuit happens when presence in a space is detected. An occupancy sensor is designed to do this: it powers the lights as soon as someone enters and typically turns them off after the space is empty for a set period. This type of sensor can use infrared or ultrasonic methods to detect presence and is commonly adjustable for how long lights stay on after occupancy ends, making it a targeted energy-saving control for spaces that aren’t always occupied.

A motion sensor can trigger lights based on movement, but it may not reliably indicate continuous occupancy, and some setups might not energize lights unless movement is detected. A timer follows a fixed schedule and doesn’t respond to whether people are actually in the room. A photoelectric switch uses ambient light levels to decide when to turn lights on or off, which is based on daylight, not people in the space.