Cable Size & Voltage Drop
Calculate the voltage drop of a cable run and the minimum conductor size for a 3% drop, free online.
About this calculator
Single-phase drop V = 2ฯLI รท A; three-phase V = โ3ฯLI รท A, where ฯ is the resistivity (copper 0.0175, aluminium 0.0283 ฮฉยทmmยฒ/m), L the one-way length in metres, I the current and A the conductor area in mmยฒ. Aim for no more than 3% on branch circuits (5% overall).