Understanding Electrical Wire Size and Voltage Drop Calculations Proper wire sizing is crucial for electrical installations, and using tools like [Co...
Formula
const resistance = inputs.wireLength * (inputs.resistancePerKFt / 1000);
const currentDraw = inputs.watts / inputs.voltage;
const voltageDrop = (2 * currentDraw * resistance) * (inputs.isPowerFactor ? inputs.powerFactor : 1);
const voltageDropPercent = (voltageDrop / inputs.voltage) * 100;
const wireArea = (2 * inputs.wireLength * currentDraw) / (inputs.conductivity * inputs.allowedDrop * inputs.voltage / 100);
return {
voltageDrop: voltageDrop.toFixed(2),
voltageDropPercent: voltageDropPercent.toFixed(2),
currentDraw: currentDraw.toFixed(2),
recommendedSize: wireArea <= 10.4 ? 14 : wireArea <= 16.5 ? 12 : wireArea <= 26.2 ? 10 : wireArea <= 41.7 ? 8 : wireArea <= 66.4 ? 6 : wireArea <= 105.6 ? 4 : wireArea <= 167.8 ? 2 : wireArea <= 211.6 ? 1 : wireArea <= 267.0 ? '1/0' : wireArea <= 336.4 ? '2/0' : wireArea <= 424.0 ? '3/0' : '4/0'
}Wire Length (ft)
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System Voltage (V)
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Load (Watts)
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Allowed Voltage Drop (%)
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Conductor Conductivity
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Wire Resistance (Ω/kft)
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Electrical Wire Size & Voltage Drop Calculator estimates Voltage Drop (V), Voltage Drop (%), Current Draw (A) based on Wire Length (ft), System Voltage (V), Load (Watts), Allowed Voltage Drop (%). Construction costs vary dramatically by location, material availability, labor market, and project complexity. Use this for rough budgeting — get at least three written quotes from licensed contractors before starting any project.
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The estimate combines Wire Length (ft), System Voltage (V), Load (Watts) and returns Voltage Drop (V), Voltage Drop (%), Current Draw (A).
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