Answer / karteek.k

there is an empirical formula to calculate voltage drop for
given cable, when you are given load in amps, i.e
(1.732x1.1xIxLxR)/1000.

1.732- square root of 3(because 3 phase circuit)
1.1- multiplication factor
I- load current in amps
L- length of the cablertee
R/1000 - resistance per kilometer

if u get voltage drop below 5% of the given voltage, i.e
415V, it will be optimum to use that cable otherwise we need
to go for next higher rating.

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