Single & Three Phase Voltage Drop Calculator

Calculate Voltage Drop









Formulas

Single-phase system:

\[ V_{\text{Drop}} = \frac{2 \times Z \times I \times L}{1000} \]

Three-phase system:

\[ V_{\text{Drop}} = \frac{1.73 \times Z \times I \times L}{1000} \]

Definitions

Impedance (Z): The opposition that a conductor offers to the flow of current, measured in ohms per 1,000 feet.

Load Current (I): The amount of current flowing through the circuit, measured in amperes.

Length (L): The length of the conductor, measured in feet.

Example Calculation

Assume a single-phase 120V circuit carries a current of 30A, where the conductor impedance is 1.5 ohms per 1,000 feet, and the circuit length is 75 feet.

Voltage drop:

\[ V_{\text{Drop}} = \frac{2 \times 1.5 \times 30 \times 75}{1000} = 6.75 \text{ V} \]

Percentage voltage drop:

\[ \text{Percentage Voltage Drop} = \frac{6.75}{120} \times 100 = 5.63\% \]