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What Size Breaker for 3/0 AWG Wire?

For 3/0 AWG wire under the displayed non-receptacle defaults, the largest common breaker is 200 A for copper and 175 A for aluminum. The copper result is the common 200 A feeder check, while aluminum remains below 200 A.
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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
Copper3/0 AWG copper200 A90 C insulation, 75 C lugs, 86 F, 3 current-carrying conductors, non-receptacle circuit default
Aluminum3/0 AWG aluminum175 A90 C insulation, 75 C lugs, 86 F, 3 current-carrying conductors, non-receptacle circuit default
What Size Breaker for 3/0 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 3/0 AWG ChangesAt 3/0 AWG, copper reaches the 200 A protection step under the displayed defaults, while aluminum remains one published answer short of 200 A. If the job is a 200 A aluminum feeder or service, compare the 250 kcmil aluminum result and equipment requirements before proceeding.

Check breaker and wire together

Adjacent Wire Sizes

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

WireCopper max breakerAluminum max breaker
2/0 AWG175 A150 A
3/0 AWG (this page)200 A175 A
4/0 AWG250 A200 A
Largest common breakers for 3/0 AWG and neighboring published wire sizes under the same defaults.

3/0 AWG Is the Copper 200 A Check

Large feeder context for 3/0 AWG wire.

A 3/0 AWG breaker-size search often comes from a 200 A feeder or service-adjacent conversation. It is also a common reverse-check when someone finds 3/0 copper already installed.

Under the displayed defaults, 3/0 AWG copper reaches a 200 A maximum breaker. 3/0 AWG aluminum reaches 175 A through the non-receptacle next-size-up path from 155 A usable ampacity, so it should not be treated as a 200 A aluminum answer.

Field Checks for This Wire Size

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

  • Do not make aluminum 200 A

    The 200 A maximum belongs to 3/0 AWG copper. The 3/0 AWG aluminum row returns a 175 A maximum breaker under the displayed defaults.

  • Name the aluminum next-size-up step

    The 175 A aluminum maximum comes from 155 A usable ampacity through the non-receptacle next-size-up default. It is not a 175 A load rating.

  • Compare 250 kcmil aluminum

    For a 200 A aluminum feeder discussion, the adjacent wire-size content points to 250 kcmil aluminum under common defaults. Confirm the actual installed conductor.

  • Run service and feeder checks

    A 200 A breaker result still needs load calculation, terminal temperature, lug range, voltage drop, utility or equipment rules, and AHJ review.

3/0 AWG Breaker FAQs

What size breaker for 3/0 AWG wire?
Under the displayed non-receptacle defaults on this page, 3/0 AWG copper has a 200 A maximum breaker and 3/0 AWG aluminum has a 175 A maximum breaker.
Can 3/0 AWG aluminum use a 200 A breaker?
No under these defaults. The 200 A result belongs to copper. The 3/0 AWG aluminum row returns a 175 A maximum breaker.
Why does 3/0 AWG aluminum show 175 A?
The 75 C ampacity path lands at 155 A, which is not a standard breaker rating. With the page's non-receptacle default, the next-size-up path reaches 175 A.
Can I use this page as final approval for a 3/0 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.