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2. Calculate Street Light Pole’s Distance / Fixture Watt / Lighting Area

CALCULATE STREET LIGHT POLE’S FIXTURE WATT / LIGHTING AREA / DISTANCE

(1) CALCULATE DISTANCE BETWEEN EACH STREET LIGHT POLE:

Example: Calculate Distance between each streetlight pole having following Details,

  • Road Details: The width of road (w) is 11.5 Foot. * Pole Details: The height of Pole is 26.5 Foot. * Luminaire of each Pole: Wattage of Luminaries is 250 Watt, Lamp Out Put (LL) is 33200 Lumen, Required Lux Level (Eh) is 5 Lux, Coefficient of Utilization Factor (Cu) is 0.18, Lamp Lumen Depreciation Factor (LLD) is 0.8, Lamp Lumen Depreciation Factor (LLD) is 0.9. * Space Height Ratio should be less than 3.

Calculation:

  • Spacing between each Pole=(LLCULLDLDD) / EhW * Spacing between each Pole=(33200×0.18×0.8×0.9) / (5×11.5) * Spacing between each Pole= 75 Foot. * Space Height Ratio = Distance between Pole / Road width * Space Height Ratio = 3. Which is less than define value.

  • SPACING BETWEEN EACH POLE IS 75 FOOT.

(2) CALCULATE STREET LIGHT LUMINAIRE WATT:

Example: Calculate Streetlight Watt of each Luminaire of Street Light Pole having following Details,

  • Road Details: The width of road (w) is 7 Meter. Distance between each Pole (D) is 50 Meter. * Required Illumination Level for Street Light (L) is 6.46 Lux per Square Meter. Luminous efficacy is 24 Lumen/Watt. * Maintenance Factor (mf) 0.29, Coefficient of Utilization Factor (Cu) is 0.9.

Calculation:

  • Average Lumen of Lamp (Al) = 8663 Lumen. * Average Lumen of Lamp (Al) =(LxWxD) / (mfxcu) * Average Lumen of Lamp (Al)= (6.46x7x50) / (0.29×0.9) * Average Lumen of Lamp (Al)=8663 Lumen. * Watt of Each Street Light Luminar = Average Lumen of Lamp / Luminous efficacy * Watt of Each Street Light Laminar = 8663 / 24

  • WATT OF EACH STREET LIGHT LUMINAIRE = 361 WATT

(3) CALCULATE REQUIRED POWER FOR STREET LIGHT AREA:

Example: Calculate Streetlight Watt of following Street Light Area,

  • Required Illumination Level for Street Light (L) is 6 Lux per Square Meter. * Luminous efficacy (En) is 20 Lumen per Watt. * Required Street Light Area to be illuminated (A) is 1 Square Meter.

Calculation:

  • Required Streetlight Watt = (Lux per Sq.Meter X Surface Area of Street Light) / Lumen per Watt. * Required Streetlight Watt = (6 X 1) / 20.

  • REQUIRED STREETLIGHT WATT = 0.3 WATT PER SQUARE METER.