cable size calcolation

British Standard 7671.

their are many ways to calculate the cable size, 1 thing you must consider is the voltage drop that must not exceed to 5% of its rated voltage from xformer to the load . another thing is that the current carrying capacity of the cable shall be sufficient to 1.25% of the actual calculated current. you will consider also if it is 3phase or single phase.

to make it accurate, you will consider the site condition, the maximum temperature, if the cable is laid by pipe, direct burried or by cable tray, Unarmored or armored cables.

but ussually the sizing of cables always depends to the load current and voltage drop.

voltage drop = X ((milli Volts/Amps) / (length of cable's))

X = the rated voltage drop of size of cable, depends upon the size of it..

its given and rated by the manufacturer

refer earlier threads on thios forum