Answer / jafar

for calculating cable size first we have to calculate load current
example 1 : 3KW POWER (1phase)
current i= 3*1000 /(230*0.8)
= 16.3A
for current carrying capacity of 1 sq mm copper is 2.4A
for current carrying capacity of 1 sq mm AL is 1.4A

now here if we use Cu then cable size is 16.3/2.4
= 6.79 is our calculated value
so we can choose near size of cable which is 10 sq mm

example 2 : 100W power (3 phase)
current i= 100*1000/(1.732*400*0.8)
= 180A

like that above
cable size is 180/2.4 = 75
so near size is 95 mm2

Answer / love kumar

for three phase copper cable is consider as 1sq mm ,3amp.
for aluminium cable 1sqmm -1amp

how to determine the cable size...pls explain me with the formula taking particular load....does the factors like impedance & short circuit rating influence the cable size, if so how....

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