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Wire size for 70 amps at 300 feet

70 A at 300 ft one-way

Voltage	Conductor	Minimum size	Voltage drop
120 V	Copper	3/0 AWG	3.22 V (2.68%)
120 V	Aluminum	250 kcmil	3.56 V (2.96%)
240 V	Copper	1 AWG	6.47 V (2.69%)
240 V	Aluminum	2/0 AWG	6.68 V (2.78%)

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

Load current (amps)

One-way length (feet)

Voltage

Conductor

Max voltage drop (%)

Continuous load?

FAQ

What size wire for 70 amps at 300 feet?

At 240 V: 1 AWG copper keeps voltage drop under 3%. See the table for 120 V and aluminum.

Same current, other distances

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