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Wire size for 300 amps at 150 feet

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300 A at 150 ft one-way

VoltageConductorMinimum sizeVoltage drop
120 VCopper350 kcmil3.30 V (2.75%)
120 VAluminum600 kcmil3.18 V (2.65%)
240 VCopper350 kcmil3.30 V (1.38%)
240 VAluminum500 kcmil3.82 V (1.59%)

Smallest size meeting NEC 75 °C ampacity (with 240.4(D) limits) and ≤3% drop at the full 300 A. Use 125% sizing for continuous loads; apply derating for more than 3 current-carrying conductors or high ambient temperature.

Adjust the numbers

FAQ

What size wire for 300 amps at 150 feet?

At 240 V: 350 kcmil copper keeps voltage drop under 3%. See the table for 120 V and aluminum.

Same current, other distances

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