Question: what is the formula for calculating voltage drop?
Answer: To calculate the voltage drop for a circuit as a percentage, multiply the current (amps) by the cable length (metres); then divide this number by the value in the table. For example, a 30m run of 6mm2 cable carrying 3 phase 32A will result in 1.5% drop: 32A x 30m = 960Am / 615 = 1.5%.