The use of improper ballasts will increase operation and maintenance costs, lower light output levels, shorten the lamp life, and waste energy. Lighting Controls Lighting controls are devices for turning lights on and off or for dimming them. The simplest type is a standard snap switch. Other controls are photocells, timers, occupancy sensors, and dimmers. Snap switches, located in numerous convenient areas, make it easier for people in large, shared spaces to turn off lights in unused areas.
Photocells turn lights on and off in response to natural light levels.
Photo-cells switch outdoor lights on at dusk and off at dawn, for example. Advanced designs gradually raise and lower fluorescent light levels with changing daylight levels. Mechanical or electronic time clocks automatically turn on and off indoor or outdoor lights for security, safety, and tasks such as janitorial work. Crank timers, which are spring-driven and similar to old oven timers, limit lights to short durations where the need for light is brief. Occupancy sensors activate lights when a person is in the area and then turn off the lights after the person has left.