How to Calculate Lux Level for Street Lighting

1. first, we must know, what is standard lux for street lighting. For example : 50 lux.

2. choose what type of Lamp will be used. whether Mercury Vapor, Metal Halide, Fluorescence.

3. How many Voltage, Wattage for this lamp.

4. How many height of the Lighting Pole.How many angel between lamp & pole (light direction)

5. E_h = IΦ x N x Cos³Φ x MF) / H²

E_h = horizontal lighting intensity level at designated point, lux

IΦ = luminous intensity of lighting fixture in the radiation direction, cd/1000

lumen (from manufacturer's photometric data)

N = lamp lumen output of lighting fixtures, Lumen

H = vertical height of lighting fixture from designated plane, feet

Φ = angle of radiation to the designated point measured against the

perpendicular to the horizontal plane, (tan ^-1 L/H), degrees

MH = Maintenance Factor

6. or use some software (like calculux, luxicon, chalmlite etc...).

When we design parking lots or streets we have the manufacturer/supplier do the photometrics.

By zoning code we are only allowed so much light to reach past the property lines so we provide the site plan and they provide the lighting layouts.

thank you

Why waste time to calculate while you can measure the lux level by lux meter or some kind of devices

Or maybe the question was wrong, it maybe meant How to design street lighting

I have been given a project where 150W MH lights are used for street lighting.The poles are of 6m height and few of them are 8m height. The pole to pole distance is 15m. Now i need to check if this will give me 20lux as per IS standard. I am not able to do the calculation with different heights.

so please suggest me where i can get the formula to calculate the lux level considering the heights.

Do you not see it in elect-ok's quote...?

yes of course,

if we just want to measure the lux, we enough use Lux-Meter.

regards

Stand under the light with a light meter.

You're bloody right.

Well as a technical person, you cannot just give a report that is only based on actual reading.. technical data must be made so you can have a good basis to your actual output this also gives you a good defense when someone disagrees with you.. haha just a thought.. :)

Just measure it!

Nothing will give you a more accurate value at any given place than that. It's like trying to determine the exact voltage, current or ohms value without a multi-meter because I cannot, can you?

Using the formulas without knowing at least one factor accurately is impossible to get the value/s right.

Your objective is more complex.

In practice, use the published distribution pattern for the lamp/fixture/pole height

combination you will use and try to get the required minimum over the entire area

served with the fewest fixtures practicable.

thanks all,

thank you for your precious replies.

Point-by-point method is used to determine the illuminance value at a point on a surface that is illuminated by direct light from a luminaire or luminaries.

For Roadway:- Average Illuminance Calculation Method

Average Luminance = (lamp lumens) x (coefficient of Utilization) x(Light loss factor)/(Spacing between luminaries)x (width of roadway)

May i know why the factor of height will not be inside the average luminance formula ? Thanks !

tHE AVERAGE LUX LEVEL IN street lighting is measured by 9 point method. you make two equal quardents between two light poles. on the lone of light poles( one side pole to road): you have 3 points p1,p2(midpoint) & p3. P1 & P2 being the points under the light pole. then p4 & p7 are points opposite pole 1 at mid of the road & opposite end of the road respectively. like wise p5 & p8 are opposite to the mid point p2 located at mid of the road & opposite side of road to p2. and p6 & p9 are mid point on road & opposite side to pole p3. the formula for avg lux = (p1+p3+p7+p9)/16+(p2+p6+p8+p4)/8+p5/4 Now there is another more accurate method 12 point has come into vouge as the 9 point assume linear distribution of lux which is not the case in reality. som derashri baroda, India

You can directly measure the intensity of light using a lux meter. Came across a good model.

http://www.industrialindia.com/catalogs/Digital_Portable_Lux_Meter/Digital-Lux-Meter-HTC-LX104.pdf

Hi som,

Cn i get a pictorial explanation fr 12 r 9 point method if two lamp pole is in the middle of the road#

Nagesh

It was great... Kindly let me know the 12 point method also...

Thanks!

Surya

tHE AVERAGE LUX LEVEL IN street lighting is measured by 9 point method. you make two equal quardents between two light poles. on the lone of light poles( one side pole to road): you have 3 points p1,p2(midpoint) & p3. P1 & P2 being the points under the light pole. then p4 & p7 are points opposite pole 1 at mid of the road & opposite end of the road respectively. like wise p5 & p8 are opposite to the mid point p2 located at mid of the road & opposite side of road to p2. and p6 & p9 are mid point on road & opposite side to pole p3. the formula for avg lux = (p1+p3+p7+p9)/16+(p2+p6+p8+p4)/8+p5/4 Now there is another more accurate method 12 point has come into vouge as the 9 point assume linear distribution of lux which is not the case in reality. som derashri baroda, India

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Thank you very much.

But I have some doubts, Why is 16, 8, 4 used in the formula? Is there any derivation for the same?

Also why is P5 considered separate? I am really confused... Kindly give me a detailed idea.

Also I am attaching two images with two representations. Kindly clarify which one is correct, also if possible, kindly state a standard where we can get these data in details.

FIG - 1:

FIG - 2:

Thanks!!!!!!!!!!!!

Surya.