Illumination Examples Sides 8 out of 8

1. Illumination Based Problems
Vijay Balu Raskar (B.E.Electtrical)

2. NOTE:-
Before Designing assume following things clearly.
Assumptions are required for illumination.
Assume Depreciation Factor = 1.2
Assume Maintenance Factor = 0.8
Utilization Factor = 0.5 to 0.9
Assume illumination is free from glare
Assume illumination is free from dark shadows
Assuming lamps are arranged to give uniform illumination.
Reflective index of wall and ceiling is maximum.
Selecting a fluorescent tube light
Space to height ratio along the length and breadth is less
than or equal to 1.5
Assume Height of mounting of Lamp ( as per area)
Vijay Balu Raskar (B.E.Electtrical)

3. Example -7
• A class room of size 15 X 6 m is to be
illuminated by twenty 200W lamps.
• The Mean Spherical Candle Power of
each lamp is 250. Assume suitable data
and find the average illumination produced
on the floor.
Vijay Balu Raskar (B.E.Electtrical)

4. Design considerations
• Assuming an average illumination of E lux.
• Assuming depreciation factor = 1.2 i.e..
Maintenance factor 0.8
• Utilization factor varies from 0.6 to 0.9
• Assume UF is 0.6
• Assuming illumination is free from glare
• Assuming illumination is free from dark
shadows.
Vijay Balu Raskar (B.E.Electtrical)

5. Design considerations
• Assuming lamps are arranged to give
uniform illumination.
• Reflective index of wall and ceiling is
maximum.
• Space to height ratio along the length and
breadth is less than or equal to 1.5
• Selecting a fluorescent tube light
• Selecting utilization factor of 0.6
Vijay Balu Raskar (B.E.Electtrical)

6. Calculation of Illumination
• We have ,
• Total Lumen = No of Lamp X MSCP X 4π
• Total Lumen = 20 X 250 X 4π
• Total Lumen = 62831.853 Lumens
• We have,
• Lumens reaching on the working plane is,
• =Total Lumens X UF = 62831.853 X 0.6
• DF 1.2
• = 31416 Lumens
• And E = Lumen reaching / Area = 31416 / 90 = 350 Lux
• Illumination is 350 Lux.
Vijay Balu Raskar (B.E.Electtrical)

7. Home Work -7
• A class room of size 20 X 5 m is to be
illuminated by twenty 300W lamps.
• The Mean Spherical Candle Power of
each lamp is 300. Assume suitable data
and find the average illumination produced
on the floor.
Vijay Balu Raskar (B.E.Electtrical)

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Contact:-
09833066325 Vijay Balu Raskar (B.E.Electtrical)