Illumination Example 1

Illumination Examples Sides 2 out of 8

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

2. Vijay Balu Raskar (B.E.Electtrical)
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)

3. Example -1
•A classroom measuring (20 m (L) X 15 m
(b) X 5 m (h) is to be illuminated.
a. State the design considerations for the
lightening of above class room
b. Calculate the no. of lamps required.
c. Draw the lighting layout.
Vijay Balu Raskar (B.E.Electtrical)

4. Design considerations
•Assuming an average illumination of 250
lux.
•Assuming depreciation factor = 1.2 i.e..
Maintenance factor 0.8
•Utilization factor varies from 0.6 to 0.9
•Assuming illumination is free from glare
•Assuming illumination is free from dark
shadows.
Vijay Balu Raskar (B.E.Electtrical)

5. •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 0.86
Design considerations
Vijay Balu Raskar (B.E.Electtrical)

6. Calculation of No. of lamps required
•From Table on Lamp Data, for the Fluorescent
lamp selecting wattage of 36 (82/84/86) with Lumen
output = 3250 (As per your data sheet)A × E
N o. of lam ps =
Flux /fitting × M .F × U .F.
(20 15) 250
=
3250 0.8 0.86
= 33.54
= 34 lamps
So, total no. of lam ps required are = 34
Vijay Balu Raskar (B.E.Electtrical)

7. Calculation for Layout
•Taking arrangement as
•No. lamps in one row = 8
•No. of rows = 4
•2 lamps for black board
•Distance along the length, a = 20/8 = 2.5m
•Distance along the width, b = 15/ 4 =
3.75m
•Side Length = a / 2 = 2.5 / 2 = 1.25m
•Side Width = b/2 = 3.75 / 2 = 1.875m
Vijay Balu Raskar (B.E.Electtrical)

8. Vijay Balu Raskar (B.E.Electtrical)
Layout

9. Vijay Balu Raskar (B.E.Electtrical)
SRatio = Spacing Between Lamps
H Height of mounting of Lamp
Along Length
Along Width9375.0
9375.0
4
75.3
Ratio
H
S 625.0
625.0
4
5.2
Ratio
H
S

10. Home Work -1
•A classroom measuring (30 m (L) X 20 m
(b) X 6 m (h) is to be illuminated.
a. State the design considerations for the
lightening of above class room
b. Calculate the no. of lamps required.
c. Draw the lighting layout.
Vijay Balu Raskar (B.E.Electtrical)

11. Vijay Balu Raskar (B.E.Electtrical)
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