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What Size Wire for 100 Amps at 250 Feet?

At 250 ft, the 100 A feeder answer moves past the 200 ft result: defaults land on 1/0 AWG copper or 3/0 AWG aluminum, so this is the next long-run planning step before the 300 ft jump.
Load
100 A
Distance
250 ft
Band
100 A feeder
Defaults
Non-continuous, 75 C lugs, 86 F, 240 V single-phase

Computed Starting Point

Ampacity and voltage drop under common defaults for this amp and distance.

MaterialComputed sizeOCPDUsable ampacityGoverning constraintDefault check
Copper1/0 AWG100 A150 AVoltage dropPasses defaults
Aluminum3/0 AWG100 A155 AVoltage dropPasses defaults
What Size Wire for 100 Amps at 250 Feet? under common non-continuous defaults: THHN or XHHW-2 insulation, 75 C terminations, 86 F ambient, 240 V single-phase and no more than three current-carrying conductors.

What 250 ft ChangesAt 250 ft, voltage drop already controls the 100 A answer, and a 50 ft measurement error can move the job into the 300 ft result. The useful decision is not whether to consider drop; it is whether the route is final enough to buy 1/0 copper or 3/0 aluminum instead of pricing the next step now.

Run the wire size calculatorCheck voltage drop alone

Zero-Length vs This Distance

If the distance-adjusted size is larger, voltage drop governed under these defaults.

CaseCopper sizeCopper constraintAluminum sizeAluminum constraint
Ampacity only (0 ft)3 AWGTermination rated 75 C1 AWGTermination rated 75 C
250 ft (this page)1/0 AWGVoltage drop3/0 AWGVoltage drop
Copper and aluminum sizes for 100 A with no distance entered versus 250 ft one-way.

Adjacent Distances at This Amp

Neighboring published lengths for 100 A under the same defaults.

DistanceCopper sizeAluminum sizeCopper constraint
200 ft1 AWG2/0 AWGVoltage drop
250 ft (this page)1/0 AWG3/0 AWGVoltage drop
300 ft2/0 AWG4/0 AWGVoltage drop
100 A copper and aluminum starting sizes across neighboring distance pages.

250 ft Is the Next Long-Run Cliff

100 A feeder context for 100 A at 250 ft.

A 250 ft 100 A feeder usually means the panel location, trench route, risers and load placement are no longer small details. A route that looked like 220-230 ft on the plan can become the 250 ft page once sweeps, verticals and equipment offsets are counted.

Compared with the refined 200 ft result, both materials move up another size under the same defaults. This page is where the decision shifts from asking whether drop matters to asking how much extra conductor, raceway and lug space the route will consume.

What Changes This Long-Run Answer

Checks that matter for distance-governed sizing in this amp band.

  • Do not reuse the 200 ft result

    Under these defaults, 200 ft lands on 1 AWG copper or 2/0 aluminum. At 250 ft the page result moves to 1/0 copper or 3/0 aluminum.

  • Measure before buying

    Include sweeps, risers, panel offsets and the final equipment location. The difference between an estimated 230 ft and a measured 250 ft can be a conductor order.

  • Check raceway and lugs early

    1/0 copper and 3/0 aluminum change conduit fill, bend space and lug acceptance compared with the shorter-run answer.

  • Preview 300 ft if the route is unsettled

    The next published distance jumps again under the same defaults. Price 300 ft before buying if trench routing or panel location is still moving.

100 A at 250 ft FAQs

What size wire for 100 amps at 250 feet?
Under the defaults on this page, start with 1/0 AWG copper or 3/0 AWG aluminum. Voltage drop is the governing constraint for both materials.
Can I use the 200 ft conductor at 250 ft?
Not under these defaults. The 200 ft page lands on 1 AWG copper or 2/0 aluminum, while the 250 ft page upsizes to 1/0 copper or 3/0 aluminum.
Should I check 300 ft before ordering conductor?
Yes if the final route is not locked. The 300 ft page is another published jump, so a route that grows after layout can change both material cost and raceway planning.