Cable Sizing & Voltage Drop Calculator

A tool to demonstrate the principles of conductor sizing based on voltage drop limitations.

How This Works

This calculator uses the standard voltage drop formula to determine the electrical potential lost across a conductor due to its internal resistance.

The Formula: VD = (K * I * R * L) / 1000

  • K: Constant representing the phase factor (2 for single-phase, 1.732 for three-phase).
  • I: Load current in Amperes.
  • R: Resistance of the conductor in Ohms per kilometer (Ω/km).
  • L: One-way length of the circuit in meters.

The code iterates through standard AWG wire sizes, looking up the DC resistance for each, until it finds a size where the calculated voltage drop percentage is below your specified limit (typically 3% for branch circuits per CEC/NEC).