Three-Phase Voltage Drop Calculations Explained

Three-Phase Power Fundamentals

Three-phase power is the backbone of commercial and industrial electrical distribution. Unlike single-phase power, three-phase systems use three conductors carrying currents that are 120 degrees out of phase with each other. This configuration provides significant advantages: more efficient power transmission, smaller conductors for equivalent power, and smoother power delivery to motors and other rotating equipment.

Understanding three-phase voltage drop is essential for designing feeders, motor circuits, and distribution systems in commercial and industrial facilities. The calculations differ from single-phase because of the phase relationships between conductors.

The √3 Factor Explained

The key difference in three-phase voltage drop calculations is the use of √3 (approximately 1.732) instead of the factor of 2 used in single-phase calculations. This factor emerges from the vector relationship between the three phases. In a balanced three-phase system, the voltages are equal in magnitude but displaced by 120°.

Line vs Phase Voltage

Understanding the relationship between line and phase voltages is critical for three-phase calculations. Line voltage is measured between any two phase conductors, while phase voltage is measured from any phase to neutral.

Common Three-Phase Systems

Three-Phase Voltage Drop Calculator

Calculate voltage drop for your three-phase circuits with our professional calculator. Select three-phase mode for automatic application of the √3 factor and accurate results for balanced loads.