In: Electrical Engineering
8. It is required to produce an illumination of 100 lux in a factory hall 30 m by 15 m. Assume that the maintenance factor is 0.8, coefficient of utilization is 0.4 and efficiency of lamp is 14 lm/W. Suggest the suitable rating, the number of lamps and their possible arrangement. The sizes of the lamps available are 100, 250, 400 and 500 W.
ANS [40 lamps of 250 W in 5 rows]
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Here I have assumed mounting height to calculate space/height ratio. This value ranges between 1 and 2.
If we use lamps of other power ratings,
Number of fittings will be increased for lower rating lamps which will not cost will increase.
And if we use lamps of higher rating, space/height ratio is not desirable.
So for 250W lamp. Ratio is 1.2 which desirable.