Power = current x voltage
Power in Watts (W)
Current in Amps (A)
Voltage in volts (V)
Applying this to find fuse rating.
Lets a lamp runs on 60W, and 220 Volts.
You have to find the current
Current = power/voltage
60/220 = 0.27
Fuses will usually come in 3A, 5A and 13A rating so the next higher will be used.
So for this lamp we will use the 3A fuse.