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What Size Breaker for 4/0 AWG Wire?

For 4/0 AWG wire under the displayed non-receptacle defaults, the largest common breaker is 250 A for copper and 200 A for aluminum. Both results depend on the next-size-up breaker-protection path, so load sizing and equipment limits need a separate check.
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4/0 AWG
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Breaker Starting Point

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

MaterialConductorLargest common breakerAssumptions
Copper4/0 AWG copper250 A90 C insulation, 75 C lugs, 86 F, 3 current-carrying conductors, non-receptacle circuit default
Aluminum4/0 AWG aluminum200 A90 C insulation, 75 C lugs, 86 F, 3 current-carrying conductors, non-receptacle circuit default
What Size Breaker for 4/0 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 4/0 AWG ChangesAt 4/0 AWG, both material rows are next-size-up protection results. That is useful for breaker compatibility, but it is not permission to treat 4/0 copper as a full 250 A load conductor or 4/0 aluminum as a full 200 A load conductor without the load, terminal, derating, and equipment checks also passing.

Check breaker and wire together

Adjacent Wire Sizes

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

WireCopper max breakerAluminum max breaker
3/0 AWG200 A175 A
4/0 AWG (this page)250 A200 A
250 kcmil300 A225 A
Largest common breakers for 4/0 AWG and neighboring published wire sizes under the same defaults.

4/0 AWG Is the Last AWG Feeder Page

Large feeder context for 4/0 AWG wire.

A 4/0 AWG breaker-size search usually means the job is at the top of the AWG series: a large feeder, service-adjacent equipment, or a check just before the project moves into kcmil conductor sizes.

Under the displayed defaults, 4/0 AWG copper reaches a 250 A maximum breaker through the non-receptacle next-size-up path from 230 A usable ampacity. 4/0 AWG aluminum reaches 200 A through the same path from 180 A usable ampacity.

Field Checks for This Wire Size

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

  • Name both next-size-up steps

    The 250 A copper result comes from 230 A usable ampacity, and the 200 A aluminum result comes from 180 A usable ampacity. Both depend on next-size-up eligibility.

  • Do not skip load sizing

    A feeder load that truly needs 250 A copper ampacity or 200 A aluminum ampacity can require a larger conductor. This page is a breaker-protection check.

  • Compare the 250 kcmil page

    The next published conductor page moves into kcmil sizing. Compare it before treating 4/0 AWG as the last word for a large feeder.

  • Verify equipment and field constraints

    Large lugs, bending space, raceway fill, 60 C terminal limits, utility requirements where applicable, and AHJ review can all change the final assembly.

4/0 AWG Breaker FAQs

What size breaker for 4/0 AWG wire?
Under the displayed non-receptacle defaults on this page, 4/0 AWG copper has a 250 A maximum breaker and 4/0 AWG aluminum has a 200 A maximum breaker.
Why does 4/0 AWG copper show 250 A?
The 75 C ampacity path lands at 230 A, which is not a standard breaker rating. With the page's non-receptacle default, the next-size-up path reaches 250 A.
Can 4/0 AWG aluminum use a 250 A breaker?
No under these defaults. The 250 A result belongs to copper. The 4/0 AWG aluminum row returns a 200 A maximum breaker.
Can I use this page as final approval for a 4/0 AWG feeder?
No. Treat it as a compatibility starting point only. Feeder work still needs load calculation, terminal temperature, conductor material, raceway fill, voltage drop, equipment listings, utility requirements where applicable, and AHJ review.