voltage drop

resistance x amps = VD

There 3 factors which needs to be considered before you go about it. 1) size ( dia ) of the conductor 2) The supply voltage . 3) The type of conductor. Once you have determined the size of the conductor the losses can be worked out with basic power formula. The diameter of the conductor will be smaller as the supply voltage increases, but losses will be higher as the dia of the conductor decreases. also the losses will be higher for aluminium conductor in comparsion to Copper. Once the Size & Type of the conductor is determined the resitance offred by the conductor for 300 meter length to carry 250 Amps current can be found from the stadard tables.

The Heat losses in a conductor can be found by using the formula I xIxR. After accounting for heat losses the voltage drop can be worked from the basic power formula.

I'm only familiar with the CEC but I'm sure the NEC has tables for calculations like that.

British Standard 7671.

What is it with all these simple volt drop questions? What is this, homework or are you an incompetent electrical worker or consultant? THIS IS BASIC STUFF YOU SHOULD KNOW!

Please look at the NUMEROUS previous posts by myself and others answering this question!!!