Question

How many 60w may be safely run on 220v using a 5a fuse?

Answer 1

you can safely use number of 60W Bulb < 16 with 4 Amp. fuse. Remember “ Watt=Applied Voltage x current” i.e W=V x I (Amp.) Lamp 60 watts, 960/60 = 16 any more addition will exceed the fuse rating.

Answer 2

Given data:

Power produced by the device = 60 W

Voltage applied to the device = 220 V

Current given to the device = 5 A

Assume the maximum number of bulbs = x

Power of x bulbs will be P = 60x

Since,

                        $P = V \times I$

                        $60x = 220 \times 5$

                        $60x = 1100$

                        $x =18.33$

Hence 18 bulbs are needed.