A domestic lighting circuit has a fuse of 5 A. If the mains supply is at 230 V, calculate the maximum number of 36 W tube-lights that can be safely used in this circuit.

Let the maximum number of tube-lights be y.

Power of y tube-lights, P=36y

V=230V, I=5A

We know that

P = VI

36y = 230 x 5

36y = 1500


So, number of tube-lights required are 31.