Skip to content
ElectraKit
Open menu

What Size Wire for 25 Amps?

For a non-continuous 25 amp load under the default short-run assumptions, start with 10 AWG copper. The calculator also shows 10 AWG aluminum only where listed aluminum terminations are available.
Load
25 A
Distance
0 ft entered
Band
Branch circuit
Defaults
Non-continuous, 75 C lugs, 86 F, 240 V single-phase
Conductor count
3 current-carrying

Computed Starting Point

The table uses common defaults. Change the calculator inputs for the actual installation.

MaterialComputed sizeOCPDUsable ampacityGoverning constraintDefault check
Copper10 AWG25 A30 ASmall conductor overcurrent limitPasses defaults
Aluminum10 AWG25 A25 ASmall conductor overcurrent limitPasses defaults
What Size Wire for 25 Amps? under common non-continuous defaults: THHN or XHHW-2 insulation, 75 C terminations, 86 F ambient, 240 V single-phase, no more than three current-carrying conductors, and 0 ft route length entered.

What 25 A ChangesAt 25 A, the page sits between the common 20 A and 30 A branch-circuit answers. The computed copper size has already moved to 10 AWG; aluminum shares the same size label only under listed aluminum terminations and with less usable ampacity margin.

Run the wire size calculator

Adjacent Amp Ratings

See whether stepping one standard size up or down forces a conductor jump under the same defaults.

LoadCopper sizeCopper OCPDAluminum sizeAluminum OCPD
20 A12 AWG20 A10 AWG20 A
25 A (this page)10 AWG25 A10 AWG25 A
30 A10 AWG30 A8 AWG30 A
Copper and aluminum starting sizes for 25 A and the neighboring published amp pages, under the same defaults as the result above.

A plateau means neighboring amp ratings share a conductor size under these defaults. A jump means a standard breaker change often needs a larger wire; confirm with your real ambient, length and terminations.

25 A Is the Nameplate Middle Case

Branch circuit context for a 25 A circuit.

A 25 A wire-size search is less often a general receptacle question and more often tied to a manufacturer-specified appliance, heater, specialty receptacle, or control circuit. The right next step is usually checking the nameplate, not guessing from a nearby common breaker.

Under the non-continuous defaults, copper moves up from 12 AWG at 20 A to 10 AWG here, then stays 10 AWG at 30 A. Aluminum is already 10 AWG at 20 A and remains 10 AWG at 25 A under the displayed assumptions, but it still needs listed aluminum terminations.

What Changes This Answer

Checks that can change the starting conductor under the displayed defaults.

  • Start with the nameplate

    Many 25 A searches come from equipment instructions. Use the manufacturer's minimum circuit ampacity and maximum overcurrent protection when provided, and do not use this page to size motor or HVAC-specific circuits.

  • Non-continuous default only

    The displayed answer does not apply the 125 percent continuous-load multiplier. If the load runs for three hours or more, rerun the calculator with continuous load enabled.

  • Do not reuse 20 A copper

    Under these defaults, 20 A uses 12 AWG copper but 25 A moves to 10 AWG copper.

  • Treat aluminum as a listed-termination case

    Aluminum is not the normal small branch-circuit shortcut. Use it only where the conductor, device and equipment terminations are listed for aluminum.

25 Amp Wire Size FAQs

What size wire for 25 amps?
Under the non-continuous defaults on this page, start with 10 AWG copper. The calculator also shows 10 AWG aluminum where listed aluminum terminations are available. Confirm the equipment nameplate before treating that as a final installation answer.
Why does 25 A use 10 AWG copper?
Under the default small-conductor limit, 12 AWG copper is a 20 A branch-circuit result. Moving to 25 A pushes copper to 10 AWG.
Is 25 A the same as a 30 A wire size?
Copper matches the 30 A page under these defaults, but the breaker and equipment requirements are not interchangeable. Use the rating that matches the equipment, and rerun continuous loads with the continuous setting enabled.
Should I use the 20 A or 30 A page instead?
Use the page matching the actual required overcurrent device or equipment nameplate. Do not round a 25 A requirement down to 20 A or up to 30 A without a project-specific basis.