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What Size Breaker for a Mini Split?

Mini-split breakers are set by the outdoor-unit MCA and MOCP nameplate — generic amp-from-tonnage charts are the wrong tool.
Appliance
Mini Split
Scope
motor-hvac
Deciding input
MCA / MOCP / motor FLA
Next
Compatibility calculator

What Decides the Breaker

Use the equipment MCA and MOCP nameplate values; this template does not override Article 440.

InputSizing basisBreaker directionStatus
Nameplate requiredNot calculatedUse MCA / MOCP or motor rulesRouted out
What Size Breaker for a Mini Split?. Use the nameplate and calculator for the actual installation.

What Actually Decides the BreakerArticle 440 path: the MOCP (maximum fuse or breaker) on the outdoor unit nameplate caps the breaker. The MCA sets the minimum conductor ampacity. A generic breaker-wire checker cannot invent those nameplate values — it can only verify a conductor against a breaker you already chose from the equipment.

Check breaker and wire together

Tonnage Charts vs the Condenser Nameplate

The job-site situation behind this search.

Search results are full of “1 ton = 15 A” style tables. Field failures come from ignoring the outdoor unit's Minimum Circuit Ampacity (MCA) and Maximum Overcurrent Protection (MOCP). Two 12k units from different brands can demand different breakers.

Multi-zone condensers compound the mistake: the outdoor nameplate already accounts for connected indoor heads. Adding indoor FLA by hand double-counts.

Worked Starting Point

A concrete path for this appliance — not a shared checklist.

Worked Starting Point: Nameplate MCA 16.5 A / MOCP 25 A

Single-zone mini-split outdoor unit, MCA 16.5 A, maximum fuse/breaker 25 A, copper conductors, 75 C terminations, short outdoor whip.

  1. Select a breaker not exceeding the MOCP: 25 A is allowed by the nameplate in this example.
  2. Select a conductor whose usable ampacity is at least the MCA of 16.5 A under the install conditions.
  3. Confirm the chosen breaker still protects that conductor under small-conductor and termination rules.
  4. Install the equipment disconnect as required by the instructions and the adopted code.

Starting point: breaker ≤ MOCP (25 A here) and conductor ≥ MCA (16.5 A here). Without the real nameplate, do not publish a tonnage-based amp answer.

Field Checks for This Appliance

Checks that matter specifically here — not the generic breaker list.

  • Copy MCA and MOCP from the outdoor nameplate

    Those two numbers are the design inputs. Do not reverse-engineer them from BTU marketing sheets.

  • Breaker may be larger than MCA

    MOCP is often a standard size above MCA. That is normal for HVAC equipment and not automatic evidence of an oversized breaker.

  • Size the conductor to MCA

    The wire must meet MCA after conditions of use. The breaker is then limited by MOCP and by what that wire can safely protect.

  • Keep disconnects and strain relief in scope

    A correctly sized breaker still fails inspection if the local disconnect, whip or strain relief skips the instructions.

Mini Split Breaker FAQs

Can I size a mini-split breaker from tons or BTU?
No. Use the outdoor unit MCA and MOCP. Tonnage charts are marketing shortcuts and routinely disagree with the nameplate that the inspector will read.
Why is the breaker bigger than the MCA?
MOCP allows a larger overcurrent device than the minimum circuit ampacity for HVAC equipment starting and protection characteristics. The conductor still has to meet MCA.
Do indoor heads need their own breakers?
Usually the outdoor unit circuit is the branch circuit of record for a ductless system, but follow the manufacturer wiring diagram. Some accessories or heaters add separate circuits.