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What Size Breaker for 8 AWG Wire?

For 8 AWG wire under the displayed defaults, the largest common breaker is 50 A for copper and 40 A for aluminum. This is the first page after the small-conductor band, so termination temperature and equipment instructions become more important than the AWG label alone.
Wire
8 AWG
Band
Mid branch / appliance
Scope
Branch / feeder check
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Compatibility calculator

Breaker Starting Point

Maximum common breaker sizes under common conditions. Derating or receptacle limits can reduce these.

MaterialConductorLargest common breakerAssumptions
Copper8 AWG copper50 A90 C insulation, 75 C lugs, 86 F, 3 current-carrying conductors, non-receptacle circuit default
Aluminum8 AWG aluminum40 A90 C insulation, 75 C lugs, 86 F, 3 current-carrying conductors, non-receptacle circuit default
What Size Breaker for 8 AWG Wire? under common non-receptacle defaults: 90 C insulation, 75 C lugs, 86 F ambient, no more than three current-carrying conductors, and next-size-up checks only where eligible.

What 8 AWG ChangesAt 8 AWG, the page leaves small-conductor 240.4(D) caps and becomes a termination and conditions-of-use check. The copper and aluminum maxima are different, and equipment limited to 60 C can reduce the apparent 75 C answer before any breaker is chosen.

Check breaker and wire together

Adjacent Wire Sizes

See whether stepping one conductor size changes the maximum standard breaker.

WireCopper max breakerAluminum max breaker
10 AWG30 A25 A
8 AWG (this page)50 A40 A
6 AWG70 A50 A
Largest common breakers for 8 AWG and neighboring published wire sizes under the same defaults.

8 AWG Is the First Appliance/Feeder Step

Mid branch / appliance context for 8 AWG wire.

An 8 AWG breaker-size search often comes from a range, cooktop, small welder, EVSE setting, water heater, or inherited light feeder. The user is usually checking whether a 40 A or 50 A breaker is reasonable after 10 AWG no longer fits the plan.

Under the displayed defaults, 8 AWG copper reaches a 50 A maximum breaker, while 8 AWG aluminum reaches 40 A. The adjacent 6 AWG page moves copper into a next-size-up case, so 8 AWG is the clean standard-rating step before the rules become easier to misread.

Field Checks for This Wire Size

Checks that matter in this conductor band — not a generic breaker list.

  • Do not reuse 10 AWG limits

    Under these defaults, 10 AWG copper tops out at 30 A and 10 AWG aluminum at 25 A. This 8 AWG page is the first larger appliance and light-feeder step.

  • Separate copper from aluminum

    The displayed copper maximum is 50 A, while aluminum is 40 A. Do not transfer the copper breaker result to an aluminum conductor.

  • Check 60 C equipment

    The table uses 75 C lugs. Equipment limited to 60 C can move 8 AWG copper down to the 40 A range and 8 AWG aluminum down to the 30 A range before project-specific checks.

  • Check continuous-load sizing

    EVSE, water-heater, and other continuous loads can require 125 percent sizing. A displayed breaker maximum does not make every continuous load at that rating compliant.

  • Use the nameplate first

    Appliances, welders, EVSE, and listed equipment can publish minimum conductor ampacity and maximum breaker values that are more specific than this generic wire-to-breaker page.

8 AWG Breaker FAQs

What size breaker for 8 AWG wire?
Under the displayed defaults on this page, 8 AWG copper has a 50 A maximum breaker and 8 AWG aluminum has a 40 A maximum breaker.
Can 8 AWG aluminum use a 50 A breaker?
No under these defaults. The 50 A result belongs to 8 AWG copper. The 8 AWG aluminum row returns a 40 A maximum breaker.
Why is 8 AWG different from 10 AWG?
The 10 AWG page is still the top small-conductor step. Moving to 8 AWG starts the appliance and light-feeder range and raises the displayed breaker maximums.
Can I use this page as final approval for an appliance circuit?
No. Treat it as a compatibility starting point. Equipment nameplates, continuous-load sizing, terminal temperature, conductor count, and local review still have to match the installation.