What is the definition of a occupancy light switch? Occupancy light switches are devices used to control lighting within a space. They are most commonly used in commercial and industrial buildings, and are designed to save energy by automatically turning the lights off when no one is present. A typical occupancy light switch consists of a sensor, a switch, and a timer. The sensor can detect the presence of someone in the room, while the switch is used to control the power to the lights. Finally, the timer can be programmed to turn the lights on and off at specific times. Occupancy light switches are a great way to save energy and money by only using the lights when necessary. They are also an important safety feature, as they can prevent people from tripping over dark areas. Overall, occupancy light switches are an essential device for any commercial or industrial building.