Abstract: A switch for controlling the operation of a light source in response to the presence of a moving person or object and in response to the magnitude of ambient light provided other than by the light source, said switch comprising means for detecting the presence of a moving body; timing means responsive to said detecting means, said timing means assuming a first condition for a selected period of time in response to the detection of a moving body by said detecting means; means for monitoring the magnitude of ambient light, said monitoring means assuming a first condition when the magnitude of ambient light is below or at a selected value and assuming a second condition when the magnitude of ambient light is above the selected value; and means for actuating a light source only when said timing means is in its first condition and when said monitoring means is in its first condition.