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Wire size for 70 amps at 250 feet

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70 A at 250 ft one-way

VoltageConductorMinimum sizeVoltage drop
120 VCopper2/0 AWG3.38 V (2.82%)
120 VAluminum4/0 AWG3.50 V (2.92%)
240 VCopper2 AWG6.79 V (2.83%)
240 VAluminum1/0 AWG7.04 V (2.93%)

Smallest size meeting NEC 75 °C ampacity (with 240.4(D) limits) and ≤3% drop at the full 70 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 70 amps at 250 feet?

At 240 V: 2 AWG copper keeps voltage drop under 3%. See the table for 120 V and aluminum.

Same current, other distances

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