The Ultimate Guide to Choosing the Right Amp Breaker for Your Mini-Split System

When it comes to installing a mini-split system in your home, one of the most critical aspects is ensuring you have the correct amp breaker. Choosing the right breaker size is essential for the safe and efficient operation of your mini-split, as well as for compliance with electrical codes. In this comprehensive guide, we’ll dive deep into the technical details and provide you with a step-by-step approach to selecting the perfect amp breaker for your mini-split system.

Understanding the Basics of Mini-Split Electrical Requirements

Before we delve into the specifics of amp breaker selection, it’s important to understand the fundamental electrical requirements of a mini-split system. These systems typically operate on 208/230V, single-phase power, and their amperage draw can vary depending on the unit’s size and specifications.

Determining the Minimum Circuit Ampacity (MCA)

The Minimum Circuit Ampacity (MCA) is the minimum amperage required to power the mini-split system. This value is typically provided by the manufacturer and is based on the unit’s maximum operating current. It’s crucial to ensure that the circuit breaker and wiring are sized to accommodate the MCA.

Calculating the Maximum Overcurrent Protection (MOP)

The Maximum Overcurrent Protection (MOP) is the maximum allowable amperage for the circuit breaker. This value is also provided by the manufacturer and is typically 125% of the unit’s full-load amps. The circuit breaker must be sized to match or exceed the MOP.

Selecting the Appropriate Amp Breaker

what amp breaker for mini splitImage source: Flickr

Now that you understand the electrical requirements, let’s dive into the process of selecting the right amp breaker for your mini-split system.

Determining the Breaker Size

As mentioned in the initial answer, a dedicated 20 to 30-amp circuit breaker is typically required for an 18,000 BTU mini-split system. However, the exact breaker size may vary depending on the unit’s specifications. To determine the appropriate breaker size, follow these steps:

  1. Locate the MCA and MOP values for your mini-split system, either from the manufacturer’s documentation or by contacting the manufacturer directly.
  2. Choose a circuit breaker size that is equal to or greater than the MOP, but not more than 125% of the MCA.
  3. For example, if the MCA is 19 amps and the MOP is 25 amps, a 30-amp circuit breaker would be the appropriate choice.

Selecting the Correct Wire Size

The power cable running from the electrical panel to the mini-split unit must be sized to handle the circuit’s amperage. For a 20-amp circuit, 12-gauge wire is typically sufficient, but 10-gauge wire can also be used. When selecting the wire size, consider the following:

  1. Ensure the wire size matches or exceeds the MCA of the mini-split system.
  2. Use copper wire, as it has a higher current-carrying capacity than aluminum wire.
  3. Verify that the wire is rated for the appropriate voltage (208/230V) and temperature (typically 75°C or 90°C).

Proper Installation and Safety Considerations

If you’re not experienced with electrical work, it’s highly recommended to have a licensed electrician handle the installation of the mini-split system and the associated electrical components. They can ensure that the breaker and wiring are properly sized, and that all connections meet the relevant electrical codes and safety standards.

During the installation process, the electrician should also consider the following:

  1. Proper grounding of the mini-split system and electrical panel.
  2. Ensuring the circuit breaker is easily accessible and labeled correctly.
  3. Verifying that the wiring is routed and secured safely, without any potential for damage or interference.
  4. Testing the system to ensure proper operation and safety.


Selecting the right amp breaker for your mini-split system is a critical step in ensuring the safe and efficient operation of your cooling or heating solution. By following the guidelines outlined in this comprehensive guide, you can confidently choose the appropriate breaker size and wire gauge, and have your mini-split system installed by a qualified professional. Remember, safety should always be the top priority when working with electrical systems.


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