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Wire size for 70 amps at 75 feet

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70 A at 75 ft one-way

VoltageConductorMinimum sizeVoltage drop
120 VCopper4 AWG3.23 V (2.69%)
120 VAluminum2 AWG3.35 V (2.79%)
240 VCopper4 AWG3.23 V (1.35%)
240 VAluminum3 AWG4.23 V (1.76%)

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.

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FAQ

What size wire for 70 amps at 75 feet?

At 240 V: 4 AWG copper keeps voltage drop under 3%. See the table for 120 V and aluminum.

Same current, other distances

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