Hi you must be more specific .... the voltage drop does not depend only on the distance Generally, in a house there are few cases in which it is necessary to calculate a voltage drop in the case of terminal circuits but if it is calculated in sectional circuits This calculator works quite well: cable calculator Keep in mind that the voltage drop 0 does not exist because there is no resistance 0, it will always have a value other than 0 there is a maximum voltage drop allowed In Argentina it is established as follows: lighting 3% engines 5% (in regime) 15% (initial) sectional circuits are recommended less than 1% but it is admitted that it is something else, provided that in conjunction with the terminal circuits it does not exceed the maximum values. For example, if the sectional falls 2% for lighting, the remaining 1% will remain the voltage drop is calculated from the main board to the farthest load taking into account the maximum circuit consumption Approximate calculation of the voltage drop in the conductors can be done using the expression: ΔU = k. I. L (R cosϕ phi + X senϕ phi) [volt] Where: k = constant equal to 2 for single phase and two phase systems and √3 for three phase systems I = intensity of the line current in ampere. L = length of the circuit in kilometers (L is the distance that separates the two points between which the voltage drop is calculated and should not be confused with the length totalized by the drivers involved) R = effective electrical resistance of the conductor at the operating temperature in ohm / km X = conductor reactance in ohm / km ϕ phi = offset angle between voltage and current Cheers