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Street lighting systems require ongoing maintenance, which can be classified as either reactive or preventative. Reactive maintenance is a direct response to a lighting failure, such as replacing a discharge lamp after it has failed or replacing an entire lighting unit after it has been hit by a vehicle.
Three photoresistors with scale in mm Large CdS photocell from a street light. A photoresistor is less light-sensitive than a photodiode or a phototransistor.The latter two components are true semiconductor devices, while a photoresistor is a passive component that does not have a PN-junction.
Yard light-garden lantern with multiple lamps.. A yard light or garden lantern is a free standing exterior light fixture in gardens and landscaped settings. They are usually illuminated by electricity, but occasionally natural gas, and are usually placed near an outdoor path or driveway to provide visibility in dark areas or areas that become dark at certain times.
Gas lamps gradually started replacing oil street lamps in the United States, beginning in the first quarter of the 19th century. [3] The first street in the world to be illuminated by gaslight was Pall Mall in London, starting in 1807. [1] [5] The first US city to use gas street lights was Baltimore, starting in 1817. [4]
The post was designed by Wood with input from PEPCO officials. Because commissioners felt that adequate illumination could only be delivered by two lights, the post had a cross-arm at the top. The post simple in its design, contained room for electrical wires and equipment in its hollow shaft and base, and was easily cleaned. [43]
A phototube or photoelectric cell is a type of gas-filled or vacuum tube that is sensitive to light. Such a tube is more correctly called a 'photoemissive cell' to distinguish it from photovoltaic or photoconductive cells. Phototubes were previously more widely used but are now replaced in many applications by solid state photodetectors.
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