Current carrying capacity of 4mm sq cable?

AS PER THUMB RULE THE CURRENT CARRYING CAPACITY OF WIRE IS 4 TIMES OF ITS CROSSECTIONAL AREA OF WIRE i.e. 10 sq.mm wire carrying maximum current 40 amp , 16 sq.mm carrying maximum current 64 amp ,

now amp convert in watt by multiplying by volt i.e. 240

16 sq.mm carrying max load 64x240= 15360 watt