Most parking lot and area
lighting commonly
uses HID type lighting fixture which stands for
high-intensity discharge lamps, HPS high
pressure sodium lamps of Metal Halide M.H. Such
lamps provide the greatest amount of photopic
illumination for the least consumption of
electricity. However when lighting calculations
are used, it can been seen how inappropriate HPS
lamps are for night lighting. White light
sources have been shown to double driver
peripheral vision and increase driver brake
reaction time at least 25%. When S/P light
calculations are used, HPS lamp performance
needs to be reduced by a minimum value of 75%.
New street lighting technologies, such as Light Emitting Diode (LED) and Induction emit a white light that provides high levels of scotopic lumens allowing street lights with lower wattages and lower photopic lumens to replace existing street lights. However, there have been no formal specifications written around Photopic/Scotopic adjustments for different types of light sources, causing many municipalities and street departments to hold back on implementation of these new technologies until the standards are updated.
Incandescent lamps were primarily used for street lighting until the advent of high-intensity discharge lamps. They were often operated in high-voltage series circuits. Series circuits were popular since the higher voltage in these circuits produced more light per watt consumed. Furthermore, before the invention of photoelectric controls, a single switch or clock could control all the lights in an entire district.
To avoid having the entire system go dark if a single lamp burned out, each street lamp was equipped with a device that ensured that the circuit would remain intact. Early series street lights were equipped with isolation transformers that would allow current to pass across the transformer whether the bulb worked or not. Later the film cutout was invented. The film cutout was a small disk of insulating film that separated two contacts connected to the two wires leading to the lamp. If the lamp failed (an open circuit), the current through the string became zero, causing the voltage of the circuit (thousands of volts) to be imposed across the insulating film, penetrating it. In this way, the failed lamp was bypassed and power restored to the rest of the district. The street light circuit contained an automatic voltage regulator, preventing the current from increasing as lamps burned out, preserving the life of the remaining lamps. When the failed lamp was replaced, a new piece of film was installed, once again separating the contacts in the cutout. This system was recognizable by the large porcelain insulator separating the lamp and reflector from the mounting arm. This was necessary because the two contacts in the lamp's base may have operated at several thousand volts above ground/earth.
New street lighting technologies, such as Light Emitting Diode (LED) and Induction emit a white light that provides high levels of scotopic lumens allowing street lights with lower wattages and lower photopic lumens to replace existing street lights. However, there have been no formal specifications written around Photopic/Scotopic adjustments for different types of light sources, causing many municipalities and street departments to hold back on implementation of these new technologies until the standards are updated.
Incandescent lamps were primarily used for street lighting until the advent of high-intensity discharge lamps. They were often operated in high-voltage series circuits. Series circuits were popular since the higher voltage in these circuits produced more light per watt consumed. Furthermore, before the invention of photoelectric controls, a single switch or clock could control all the lights in an entire district.
To avoid having the entire system go dark if a single lamp burned out, each street lamp was equipped with a device that ensured that the circuit would remain intact. Early series street lights were equipped with isolation transformers that would allow current to pass across the transformer whether the bulb worked or not. Later the film cutout was invented. The film cutout was a small disk of insulating film that separated two contacts connected to the two wires leading to the lamp. If the lamp failed (an open circuit), the current through the string became zero, causing the voltage of the circuit (thousands of volts) to be imposed across the insulating film, penetrating it. In this way, the failed lamp was bypassed and power restored to the rest of the district. The street light circuit contained an automatic voltage regulator, preventing the current from increasing as lamps burned out, preserving the life of the remaining lamps. When the failed lamp was replaced, a new piece of film was installed, once again separating the contacts in the cutout. This system was recognizable by the large porcelain insulator separating the lamp and reflector from the mounting arm. This was necessary because the two contacts in the lamp's base may have operated at several thousand volts above ground/earth.
