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Wire size for 100 amps at 300 feet

100 A at 300 ft one-way

Voltage	Conductor	Minimum size	Voltage drop
120 V	Copper	250 kcmil	3.09 V (2.57%)
120 V	Aluminum	400 kcmil	3.17 V (2.64%)
240 V	Copper	2/0 AWG	5.80 V (2.42%)
240 V	Aluminum	4/0 AWG	6.00 V (2.50%)

Smallest size meeting NEC 75 °C ampacity (with 240.4(D) limits) and ≤3% drop at the full 100 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 100 amps at 300 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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