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Wire size for 125 amps at 250 feet

125 A at 250 ft one-way

Voltage	Conductor	Minimum size	Voltage drop
120 V	Copper	250 kcmil	3.22 V (2.68%)
120 V	Aluminum	400 kcmil	3.31 V (2.76%)
240 V	Copper	2/0 AWG	6.04 V (2.52%)
240 V	Aluminum	4/0 AWG	6.25 V (2.60%)

Smallest size meeting NEC 75 °C ampacity (with 240.4(D) limits) and ≤3% drop at the full 125 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 125 amps at 250 feet?

At 240 V: 2/0 AWG copper keeps voltage drop under 3%. See the table for 120 V and aluminum.

Same current, other distances

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