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\u{1F50B} Voltage Drop Calculator
Calculate voltage drop across copper wire runs. Helps ensure your wiring meets NEC recommendations of less than 3% drop.
Understanding Voltage Drop
Voltage drop is the reduction in voltage as electrical current flows through a wire. It is calculated as VD = 2 × I × R × L / 1000, where the factor of 2 accounts for the round-trip distance (both supply and return conductors).
The NEC recommends a maximum voltage drop of 3% for branch circuits and 5% total for feeder plus branch circuits combined. Excessive voltage drop causes inefficiency, dimming lights, and underperforming motors.
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