Power Saving Sensor Light Switches

In some cases lights are kept ON even when they are not necessary, thus wasting power. For example, in office cabins, in lifts, in passages, in staircases, on periphery of buildings, in gardens, in washrooms, outside the door, in lobbies, etc. Energy Saving Sensor Light Switches have two sensors : (a) an ambient light sensor, which senses the ambient light conditions so that the lights should be switched ON only when it is darker; and (b) a human PIR sensor which senses the presence of a human being to switch ON the light. As a result, the lights, which are controlled by such switches, are automatically switched OFF when there are no persons around OR the ambient light is bright.