What is a Photocell?
Technically, a Photocell is a light sensor that varies its resistance between its two terminals, based on the amount of light received by the photocell. In other words, it is a sensor that detects light, and turns your light fixture on as it senses less available light (usually around dusk) and turns the light fixture off when it senses more light (usually around dawn) -- as a result, the feature is called a 'dusk to dawn' feature.
By using both a photocell and a motion detector built into a motion light, the system will turn on only when both (a) motion is detected by the main motion sensor AND (b) the photocell detects that less light is available (dusk). Then, when the photocell detects that more light is available (dawn), the light will not operate, even when motion is detected.
Some of the Benefits
By using fixtures equipped with a Photocell, you will save money and energy. Fixtures that use a Photocell will turn on and off at the appropriate time without having to remember to flip a switch, ensuring that your light will not operate during daylight hours when it is not needed.
