Mini Split Electrical Requirements (Breaker Size + Wire Gauge)
Most mini split systems require a dedicated breaker and correctly sized wire based on the unit’s MCA (Minimum Circuit Ampacity) and MOP (Maximum Overcurrent Protection) rating on the nameplate. Many 9k–12k BTU mini splits use a 15–20 amp breaker, while larger 18k–36k systems often require 20–40 amps, depending on model and voltage. Always size your breaker and wire to the manufacturer specs and local electrical code.
Last updated: January 2026
Key Takeaways
- ✅ Always follow the unit’s MCA and MOP (nameplate > guesses)
- ✅ Most mini splits need a dedicated circuit
- ⚠️ Breaker size and wire gauge vary by BTU, voltage, and model
- 💡 When in doubt, confirm using the equipment spec label or manual
Mini Split Breaker Size + Wire Gauge (General Guide)
Important: This chart is a general reference. Always verify with your exact unit’s MCA/MOP and local code.
| Mini Split Size (BTU) | Typical Voltage | Common Breaker Range | Common Wire Gauge Range |
|---|---|---|---|
| 6,000 – 9,000 | 115V or 230V | 15A – 20A | 14 AWG – 12 AWG |
| 12,000 | 115V or 230V | 15A – 25A | 14 AWG – 10 AWG |
| 18,000 | 230V | 20A – 30A | 12 AWG – 10 AWG |
| 24,000 | 230V | 25A – 40A | 10 AWG – 8 AWG |
| 30,000 – 36,000 | 230V | 30A – 50A | 10 AWG – 6 AWG |
Common Mistakes to Avoid
-
Mistake #1: Using “BTU size” only to pick a breaker
Two 12k units can have totally different electrical requirements depending on efficiency and design. -
Mistake #2: Ignoring the nameplate
The manufacturer gives MCA/MOP for a reason. That’s what inspectors care about. -
Mistake #3: Undersizing wire
A breaker might hold, but the wire can still overheat. Don’t do that.
FAQ
Q: What breaker size do I need for a mini split?
A: It depends on the unit’s MOP rating, which tells you the maximum breaker size allowed. Many small systems are 15–20A, while larger systems may require 30–50A.
Q: What wire gauge do I need for a mini split?
A: Wire size is based on MCA and wire run length. Many smaller systems use 14–12 AWG, while larger systems may need 10–6 AWG. Always follow the manufacturer’s MCA and local code.
Q: Do mini splits need a disconnect box?
A: In most installs, yes. A disconnect near the outdoor unit is commonly required by code and is also helpful for servicing.
Q: Can I use a 20 amp breaker for a 12,000 BTU mini split?
A: Sometimes. Some 12k units are fine on 15–20A, but others require 25A or more. Always verify using the nameplate MCA/MOP.
Q: What do MCA and MOP mean?
A: MCA is the minimum circuit ampacity (minimum wiring capacity). MOP is the maximum overcurrent protection (maximum breaker/fuse allowed).
Recommended Products
- Shop MRCOOL Mini Split Systems
- Shop Mini Split Installation Accessories
- Shop Electrical Disconnects, Whips, and Breakers
Related Guides
- Mini Split BTU Sizing Chart (By Square Footage + Room Type)
- Mini Split Line Set Length Guide (16, 25, 35, 50, 75 ft)
- Mini Split Installation Checklist (Tools, Parts, and Common Mistakes)