What Size Breaker For 12,000 – 36,000 Btu Mini Split?

You need a minimum 25 amp breaker for mini split systems up to 24,000 BTU/2 tons. A 30 amp breaker is sufficient for 36,000 BTU/3 ton systems, and a 50 amp breaker meets requirements for larger units to 60,000 BTU/5 tons. All the details follow. 

If you are going to install a ductless mini split AC or heat pump unit, three factors that you need to consider are: size of the unit needed, voltage required, and amperage of the circuit breaker(s) needed. This article will explain how each of them differs and the relationship they have to each other. 

Breaker Size Required Mini Split ACs and Heat Pumps

Every mini split needs electricity to operate the compressor, cooling fan, and control circuits in the outdoor component of the system. As the size of the system increases, so does the amount of electricity needed to operate it. 

Look at the Mini Split Breaker Amps for BTU Chart below to see this illustrated. 

What size breaker for 9,000 – 36,000 btu mini split

Mini Split BTUVoltBreak Size
9,000 BTU110V15 Amp
12,000 BTU220V15 Amp
18,000 BTU220V20 Amp
24,000 BTU220V25 Amp
36,000 BTU220V30 Amp

* based on 12 eer

Example 1: You might ask, “what size breaker for 12,000 btu mini split?”

Find 12000 on the chart above, and you’ll see that a 12,000 BTU mini split needs a 15 amp breaker. 

Example 2: “What size breaker do I need for a pioneer 18000 btu mini split?”

According to the Breaker Amps for Mini Splits Chart, the breaker should be a minimum of 20 amps. 

Here is the information for Mini Split Breaker Amps for AC Tons Chart. 

1 – 5 ton Mini Split AC Breaker Size

Mini Split TonVoltBreak Size
1 Ton220v15 Amp
1.5 Ton220v20 Amp
2 Ton220v25 Amp
3 Ton220v30 Amp
4 Ton220v40 Amp
5 Ton220v50 Amp

* The chart is based on 12 eer

What is the Mitsubishi 3 ton mini split breaker size?

Regardless of brand, a 3 ton mini split needs a 30 amp breaker. 

Different Voltages 120 or 110? 240 or 220? – Don’t be Confused

Whenever you see voltages of appliances using electricity listed, you may wonder why they are sometimes different. The fact is, in the U.S., the standard voltage in the wiring coming into your home is 240v. 

In the main circuit breaker box, this is split in half for some circuits so that you now have either 240v or 120v available for each of the different circuits. 

Because electricity travels from the main box to the various places in your home through wires that produce resistance, the voltage at the far end isn’t the same as it was at the main box. This is called “voltage drop”. 

Voltage drop means that though it may have measured 120v at the main box, it may now be only 115v – or possibly even 110v at the receptacle in a bedroom at the other end of the house, for example. The circuit for an AC unit, which traveled all the way through your house to the disconnect box on the outside wall may have been 240v at the main box, but now might measure 230v – or even 220v. 

This is not a problem, however, because most appliances and electrical devices are made to function on these voltages, knowing that they will vary due to the voltage drop through the wiring. So don’t be confused; 110v, 115v, and 120v all refer to the same thing, as do 220v, 230v and 240v.                                                                                         

But back to the chart – as you can see, only the smaller units will operate efficiently with the lower voltage circuit – 110v. The majority of them require a 220v circuit. 

This means that both the circuit breaker in the main box and the wires running from that box to the disconnect box near the mini split unit will be larger, so they can handle the higher voltage and amperage of that circuit. 

This brings us to the third item in our list of factors to consider, which is the circuit breaker. 

Amperage of the Circuit Breaker Needed 

As the size of any electrical appliance increases, so does the need for larger circuit breakers and larger wires to carry the electricity. 

So, for example, if you wanted to know what size breaker for a 12,000 BTU mini split, the chart above tells you that 15 amp breakers (2 breakers for a 220v circuit) are to be used. 

If you need to know what the recommended Mitsubishi 3 ton mini split breaker size is, it’s easy to see that the answer is 30 amp. 

And if you are wondering, “what size breaker do I need for a Pioneer 18000 BTU mini split,” the chart will show that 20 amp breakers are to be used. 

It doesn’t matter if it’s a MR COOL, a Pioneer, or some other brand, it’s the electrical power requirements of the system that determines the size of the circuit breakers. 

Size of the Mini Split Needed 

The first thing you will want to consider is how large the space is that you want to cool (or heat if you want a heat pump mini split). Along with this is whether you are just wanting to cool one room or more than one. This will determine the cooling capacity of the unit that you need to purchase, as well as whether you need a single zone, 2 Zone, or even more. 

To determine the size of the mini split for your application, you will need to know the square footage of your space. Then you can refer to a chart which will show you what size mini split will efficiently cool that space. You will find the size of mini splits given in either BTU’s or Tons, which are simply two different ways of listing their cooling capacity. 

Info Tip: The Pick HVAC Mini Split Buying Guide gives clear guidance on sizing your mini split for your home’s needs.

Mini Split Electrical FAQ’s 

What size breaker for 2 zone mini split?

The answer depends on the voltage and size of the system. A 20 amp breaker is sufficient for a 18,000 BTU 2 zone system with two 9,000 BTU indoor units. If the indoor units are each 18,000 BTU and the condenser is a 36,000 BTU unit, the breaker needed is 30 amps. Any 2 zone system, or 3+ zones, of 48,000 BTU or more requires a 40 amp breaker. 

What size breaker for a 115v mini split?

All 115-volt mini split ACs and heat pumps require a 15 amp circuit. 

A thing called a “disconnect box” was mentioned in this article – what is that? 

Any AC unit – whether traditional or mini split – must have an electrical disconnect box mounted on the outside of the building within a few feet of the unit itself. 

The purpose of this is so the power can be completely disconnected from the unit by anyone performing maintenance or repairs on the unit. This gives the technician complete control of the electricity and eliminates the possibility of someone else turning the power on to that circuit from inside the building when the technician thought it was off. In short, it’s a safety thing. 

Does the breaker size change if I have a multi-zone mini split?

Not really. It isn’t the number of zones that determines the size of the circuit breakers, but the total cooling capacity of the unit. 

As the charts above show, as the cooling capacity increases, the breaker size also increases. A multi-zone mini split will still have a total (combined) capacity, but this will be divided among the different zones.

Written by

Rene has worked 10 years in the HVAC field and now is the Senior Comfort Specialist for PICKHVAC. He holds an HVAC associate degree and EPA & R-410A Certifications.
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2 thoughts on “What Size Breaker For 12,000 – 36,000 Btu Mini Split?”

  1. If I run a 220V 30amp circuit to power 2 single zone mini splits, can I use a 15amp fused disconnect for the 12000 BTU unit and a 20amp fused disconnect for the 18000BTU unit. Each unit will have its own rated fused protection, and the circuit would cover the combined 30amp load when both units are running.

    • Hi Steve,

      Do you have the detailed running amperage of the two units. Usually it will work when you not starting the two units off together but I am not 100% sure until see the detailed metrics.


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