Calculate No of Street Light Poles

Calculate No of Street Light PolesTypical Calculation of Road Lighting:  Luminaries are properly selected and mounted on a location most feasible and effective with minimum cost. For a 230 volts system, a voltage drop of 5% is allowed although in extreme cases 15% voltage drop is sometimes tolerated.      Street illumination level in Lux (E)=(Al x (cu x mf)) / (w x d) E = The illumination in Lux w = Width of the roadway d = Distance between luminaries cu = Coefficient of utilization. Which is dependent on the type of fixture, mounting height, width of roadway and the length of mast arm of outreach?        Al = Average lumens, Al = (E x w x d) / Cu x mf The typical value of Al is 20500 lumens for 400 watts 11500 lumens for 250 watts 5400 lumens for 125 watts The value of Al varies depending upon the type of lamp specified. mf : It is the maintenance factor (Normally 0.8 to 0.9) (1) Calculate Lamp watt for street Light Pole:  Calculate Lamp Lumen for street Light Pole having Road width of 7 meter, distance between two Pole is 50 meter, Maintenance factor is 0.9, Coefficient of utilization factor is 0.29, light pedestrian traffic is medium and Vehicular traffic is very light and Road is concrete road. Solution: From Above table Recommended of illumination (E) in Lux is 6.46 per sq. meter. w = 7.00 meters , d = 50 meters , mf = 0.9, cu = 0.29 To decide Lamp Watt It is necessary to calculate Average Lumens of Lamp (Al).   Average Lumen of Lamp (Al)=(E x w x d) / Cu x mf Al=(6.46x7x50)/(0.29×0.9)= 8662.83 Average lumen Lamp lumen of a 250 watts lamp is 11,500 lm which is the nearest value to 8662.83 lumen. Therefore, a 250 watts lamp is acceptable. Let’s Computing for the actual illumination E for 250 Watt Lamp   Illumination (E)=(Al x (cu x mf)) / (w x d) E= (11500×0.29×0.9) / (7×50) = 8.57 lumen per sq meter. Conclusion: Actual illumination (E) for 250 Watt is 8.57 lumen per sq meter which is higher than recommended illumination (E) 6.46.  Hence 250 watt gives adequately lighting. (2) Calculate Spacing between two Light Poles: 48) (3) Calculation of the allowed illumination time: The allowed illumination time in hours T = k. the cost of running a light is directly related to the wattage of the globe plus any associated ballast or transformer.8) / (5×11.Height of the pole (H) = 26. Required Lux Level (E) is 5 lux .18. the higher the running cost and it is a straightforward calculation to work out the running cost of lamp over its lifetime: .5 Halogen capsules 2. In halogen light (200 lux) and extension factor 2.3 x 70 x 1000/200 = 805 hours.5 x 70 x 1000/200 = 1225 hours.1 High-pressure sodium lamps 4 Fluorescent lamps 1.9×0.7    Example: In sunlight (100000 lux) and extension factor 1: The permissible illumination time (T) =1 x 70 x 1000/100 000 = 0.  In UV-filtered halogen light (200 lux) and extension factor 3.18×0. The higher the wattage.8 . Width of the road (W) = 11.     Where: k = extension factor t = permissible time in hours at 1000 lux. (4) Calculate Uniformity Ratio:  Once luminaries spacing has been decided It is necessary to check the uniformity of light distribution and compare this value to the selected lighting    Uniformity Ratio ( UR) = Eav /Emin Eav= average maintained horizontal luminance Emin = maintained horizontal luminance at the point of minimum illumination on the pavement (5) Energy Saving Calculations:  At a simplistic level.48 feet (3. 2.Calculate Space between Two Pole of Street Light having Fixture Watt is 250W . unfiltered daylight E = luminance (lx) Extension Factor Lamp Extension Factor Incandescent lamps.9 to 2.1000/E.1 to 2.7 to 3. Lamp Lumen Depreciation Factor (LLD) = 0.5 M).3: The permissible illumination time (T) = 2.7 hour.5 High-pressure metal-halide 1.t.Luminaries dirt Depreciation Factor (LDD) = 0.5: The permissible illumination time (T) = 3. Lamp output of the Lamp (LL) is 33200  lumens .5 to 3.9 Solution:   Luminaries Spacing (S) = (LLxCUxLLDxLDD) / (ExW)  Luminaries Spacing (S) = 75 feet (23 Meters) Luminaries Spacing (S) = (33200×0.24 feet (8 M) .Coefficient of utilization (CU) = 0.5 to 3.2 Halogen reflector lamps 2. Make two equal quadrants between two Street light poles.P2 and P3 under the light pole then P4 & P7 are points opposite pole 1 or Point P3 same is applicable for P6 and P9 for Pole 2. Running cost = cost of electricity in $/kWh x wattage of lamp x lifetime in hours. Calculate Lux Level for Street Lighting  The Average Lux Level of Street Light is measured by 9 point method. on the lane of light poles( one side pole to road).  We have 3 points P1.  The average lux = [(P1+P3+P7+P9)/16]+[(P2+P6+P8+P4)/8]+[P5/4] .