Design Standards for Subdivision
Average maintained illumination: | |||
fc + (A) x (B) x (C) x (D) x (E) (F) | |||
Where: | |||
fc | = | Footcandles | |
A | = | Number of luminaires per pole | |
B | = | Horizontal initial lamp lumens per luminaire | |
C | = | Beam efficiency | |
D | = | Coefficient of utilization | |
E | = | Total light loss factor | |
F | = | Length x width of area to be illuminated (for area lighting, e.g. parking lot) or spacing between luminaries x width of roadway (for roadway lighting) | |
Variables B, C, D and E can be obtained from manufacturer's photometric specifications prepared for all luminaires, while Variables A and F are a function of the particular site and lighting system proposed. Since this equation can be solved for any variable, the formula can be used to calculate average maintained illumination as well as appropriate pole spacing and number of poles required for a desired level of illumination. In addition to completing a mathematical calculation of average maintained illumination, isolux curves which depict average to be lighted should be shown on the lighting plan for luminaires. | |||
Design Standards for Subdivision
Average maintained illumination: | |||
fc + (A) x (B) x (C) x (D) x (E) (F) | |||
Where: | |||
fc | = | Footcandles | |
A | = | Number of luminaires per pole | |
B | = | Horizontal initial lamp lumens per luminaire | |
C | = | Beam efficiency | |
D | = | Coefficient of utilization | |
E | = | Total light loss factor | |
F | = | Length x width of area to be illuminated (for area lighting, e.g. parking lot) or spacing between luminaries x width of roadway (for roadway lighting) | |
Variables B, C, D and E can be obtained from manufacturer's photometric specifications prepared for all luminaires, while Variables A and F are a function of the particular site and lighting system proposed. Since this equation can be solved for any variable, the formula can be used to calculate average maintained illumination as well as appropriate pole spacing and number of poles required for a desired level of illumination. In addition to completing a mathematical calculation of average maintained illumination, isolux curves which depict average to be lighted should be shown on the lighting plan for luminaires. | |||