Question

Example 7.26 A hall 30m Long and 12m wide is to be illuminated and illumination required is 50 matre Candles Five types of lamps having lumen outputs as given below are available 300 500 1.000 Lumens 1.615 3.650 4.700 9.950 21.500 Taking a depeciation factor of 1.3 and utilisation coefficient of the number of lamps needed in each case to produce required illumination out of above five types of lamps select most suitable type and design a Suitable scheme and make a sketch showing Location of lamps Assuma asuitable mounting height and calculate space-heigh ration of lamps ​

Answer 1

Area of the hall = length x width = 30m x 12m = 360 sq. m

Illumination required = 50 meter-candles

Total lumens required = area x illumination required = 360 x 50 = 18,000 lumens

Now, we can find the number of lamps needed for each type of lamp by dividing the total lumens required by the lumen output of each lamp, and then accounting for the depreciation factor and utilization coefficient:

For 300 lumen lamp: (18,000 / 300) x 1.3 x 0.4 = 31.2 lamps (round up to 32 lamps)

For 500 lumen lamp: (18,000 / 500) x 1.3 x 0.4 = 22.9 lamps (round up to 23 lamps)

For 1000 lumen lamp: (18,000 / 1000) x 1.3 x 0.4 = 13.5 lamps (round up to 14 lamps)

For 1615 lumen lamp: (18,000 / 1615) x 1.3 x 0.4 = 8.6 lamps (round up to 9 lamps)

For 3650 lumen lamp: (18,000 / 3650) x 1.3 x 0.4 = 3.9 lamps (round up to 4 lamps)

For 4700 lumen lamp: (18,000 / 4700) x 1.3 x 0.4 = 3 lamps (round up to 3 lamps)

For 9950 lumen lamp: (18,000 / 9950) x 1.3 x 0.4 = 1.4 lamps (round up to 2 lamps)

For 21500 lumen lamp: (18,000 / 21500) x 1.3 x 0.4 = 0.9 lamps (round up to 1 lamp)

The most suitable type of lamp would be the 1000 lumen lamp, as it requires the least number of lamps to produce the required illumination. A suitable scheme could involve mounting 14 of these lamps evenly spaced throughout the hall, at a mounting height of around 4-5 meters. The space-height ratio of the lamps would be around 1:1, meaning that the distance between each lamp would be roughly equal to the mounting height.

Step-by-step explanation: