Voltage Drop Calculator
Calculate electrical voltage drop across feeders and branch circuits to ensure NEC compliance and optimal equipment performance. Supports AC/DC systems.
Circuit Parameters
NEC Recommendation:
Excellent! Your drop is within the 3% feeder recommendation.
Understanding the Voltage Drop Formula
A professional voltage drop calculator follows the Chapter 9, Table 8 of the NEC (National Electrical Code). Whether you are installing a new AC unit, a Tesla wall connector, or running power to a detached garage, knowing the exact voltage drop calculation is vital for electrical safety.
How to Calculate Voltage Drop for Single and Three Phase
The formula for single phase is Vd = (2 * K * L * I) / CM. For three-phase systems, we use the square root of 3 (1.732) as the multiplier: Vd = (1.732 * K * L * I) / CM. Our online voltage drop tool automates these complex physics equations so you can select the right AWG wire size without guessing.
Frequently Asked Questions
Everything you need to know about this calculator and the underlying logic.