To find the voltage drop on a circuit , you need to know the cable size , the cable length and load current.
Using the formula Vd = I x L x Vc / 1000 Vc is the milliVolts per Amp x Mtrs lost.
This will give you the Volts drop : Vc can be found in AS3008 Tables 40 - 42 , mostly use 75 degree as this is cables maximum temperature . Worst case scenario.
You can also then find what % voltage loss is compared to supply voltage . 400 V or 230 V.
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