devarshi-dt-logo

Question:

In a large building, there are 15 bulbs of 40 W, 5 bulbs of 100 W, 5 fans of 80 W and 1 heater of 1kW. The voltage of the electric mains is 220 V. The minimum capacity of the main fuse of the building will be:

12 A

8 A

14 A

10 A

Solution:

Item No. Power
40 W bulb 15 600 Watt
100 W bulb 5 500 Watt
80 W fan 5 400 Watt
1000 W heater 1 1000 Watt
Total Wattage=2500 Watt
So current capacity
i=P/V=2500/220=125/11=11.36 ≈12Amp.