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Illumination - Scenario 1

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This post is inspired by Problem 27, Chapter 20 (Illumination) of "Textbook-Reviewer in Electrical Engineering, 1st Edition" by Professional Electrical Engr. (PEE) Marcialito M. Valenzona.

SITUATION

An industrial work area of 33 meters by 13 meters needs an illumination level of 72 lumens per square meter using 200W lamps with 2730 lumens of output per lamp. The area's coefficient of utilization is 40% and its maintenance factor is 71%. How many lamps does the area need?


ANALYSIS

1.) Desired work area illumination:

(72 lumens/m^2) * (33*13)m^2 = 30,888 lumens

2.) Lumens from sources:

Coefficient of utilization is the lumens reaching the work area (diminished by absorption and reflection) over the lumens emitted by sources.

30,888 lumens / 0.4cu = 77,220 lumens

3.) Lumens when clean/new:

Maintenance factor is the lumens emitted by source under normal working conditions (dust, dirt, smoke, etc) over the lumens emitted when everything is completely clean or brand new.

77,220 lumens / 0.71mf = 108,760.56 lumens

4.) Total number of lamps needed:

108,760.56 lumens / (2730 lumens/lamp) = 39.84 lamps

CONCLUSION

The factory area needs 40 lamps to reach the desired level of illumination.

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