Which device is commonly used to automatically turn lighting on when a room is occupied?

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

Answer: (C)

Automatic lighting control relies on detecting whether a space is in use. An occupancy sensor is designed to sense people in a room and automatically turn the lights on when someone is present and off after the space is vacated. This is why it’s the best fit for turning lighting on automatically when a room is occupied. It improves energy efficiency by reacting to actual use rather than a fixed schedule or ambient conditions.

Dimmers adjust brightness but don’t automatically turn lights on based on occupancy. Timers run on a set schedule, regardless of whether someone is in the room. Photoelectric switches respond to ambient light levels, turning lights on or off according to daylight, not occupancy.