Question

A drawing hall 30 m by 15 m with a ceiling height of 5 m is to be provided with general illumination of 120 lux. Taking a coefficient of utilization of 0.5 and depreciation factor of 1.4, determine (a) the number of fluorescent tubes required, (b) their spacing, mounting height and (c) total wattage. Taking luminous efficiency of fluorescent tube as 40 lm/W for 80 W tubes.

ANS: [(a) 48, 24 twin-tube units each tube of 80 W;

(b) Row spacing of 5 m and unit and unit spacing of 3.75 m, (c) 3,840 W]

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Answer 1