How To Wire Up a Mini Split Air Conditioner or Heat Pump

By | August 28, 2020

How To Wire Up a Mini Split

Page Table of Contents
Wiring Mini Split DC Control Lines
Wiring a Mini Split Electric AC
Items Needed for AC Electrical
Mini Split Wire Gauge
Wiring a Disconnect Box To Mini Split
Wiring from Breaker Panel to the Disconnect Box

Wiring up a Mini Split HVAC unit is not difficult but does require some basic electrical knowledge.

This post gives a basic overview of wiring up a mini split.

The instructions that come with any unit should always be followed.

There is two types of wiring that will need to be done.

1… Electrical AC Power (Usually labeled L1, L2, and Ground)
2… DC Control Voltage (Usually labeled 1, 2 ,3)

The AC electrical voltage will be 110-120 or 220-230 Volts.
How To Wire Up a Mini Split Panel
It will be supplied from an electrical panel which will hold all the breakers for a home.

The breaker will need the correct amps the mini split is rated for and will be displayed on the breaker.

For example, a breaker labeled 15 will be a 15 amp breaker or 20 will be 20 amp breaker.

Electrical AC wiring will need to be bought separately from DIY mini split kits and is not included.

The DC control wires go between the inside and outside units.

There is usually 3-5 DC control lines which are easy to wire up.
How To Wire Up a Mini Split DC wires 2
DC control lines are included in most any good DIY mini split install package.

Wiring Mini Split DC Control Lines

  • Run the Control Wires
  • Match the wires color to the labeled numbers

Most Mini Split units will have the inside and outside units marked with numbers 1, 2, 3, and ground which the wires color code will match.
How To Wire Up a Mini Split Panel DC wires inside
For example, if a red wire is connected to the inside number 1 it will be connected outside to the labeled 1.

Wiring the control lines is a straight forward and easy enough by simply matching wires colors to the labeled numbers.

Most all DIY mini split kits will come with the DC control line wiring.

Wiring a Mini Split Electric AC

  • Know the Voltage (110-115/220-230)
  • Know the Amps
  • Use the Right Breaker Size
  • Use the Right Wire Gauge

Wiring the AC electrical needs to be thought out with each situation different.

Mini Split units come in all sizes which have different voltage and amps.
How To Wire Up a Mini Split label
The voltage as well as amps will be in the instructions and on the unit itself.

Voltage will be the standard 110-115 or 220-230 volts most all homes use.

The amps it draws to run will also be rated.

The unit will need the rated breaker size to run the unit and trip off if there is a problem.

As most know this is what a breaker does it shuts off stopping the flow of power if there is a problem.

Items Needed for AC Electrical
Most all mini spits units will need a disconnect box placed close to the unit to turn on and off the power.

A disconnect box is simply a junction that like a switch turns on and off the power when needed.

Disconnect Box on Amazon
SIEMENS WN2060U Non-Fused AC Disconnect

Mini Split Wire Gauge
Wire gauge is how thick the wire is with different sizes for different voltages and amps.

Gauge Size Amps Example Uses
16 Gauge 13 Amps Extension cords
14 Gauge 15 Amps Lamps / Lights
12 Gauge 20 Amps Outlets / Some Mini Splits
10 Gauge 30 Amps Clothes Dryers / Some Mini Splits
8 Gauge 60 Amps Electric Stoves Furnaces

The wire gauge needed will be in the instructions with common sizes for mini split units being 10-12 gauge.

While most units will be 10-12 gauge be sure to read the specifications to get the correct size wire.

Wiring a Disconnect Box To Mini Split
Disconnect Boxes are simple to wire up with power coming in and going out.

The box will have wiring coming from the breaker and going out to the mini split.
How To Wire Up a Mini Split Disconnect 2
They have a pull out that turns the power off and on.

The wires are fed into the outside condensing unit and usually marked L1 and L2 along with green for ground.
How To Wire Up a Mini Split DC wires 2

An electrical whip is commonly used to go from the disconnect box to the mini split.
How To Wire Up a Mini Split Whip
A whip is a prepackaged electrical line that is quick and easy to install.

Electrical wires will need to be run from the breaker to the disconnect box with an electrical whip making it quick and easy to run to the mini split unit.

Electrical Whip on Amazon
Sealproof Power Whip Assembly, 1/2-Inch x 6 Ft Nonmetallic Liquid Tight Flexible Electrical Conduit and 10 Gauge Wire Single Phase Preassembled A/C Hook-up Whip Kit, 1/2″

Wiring from Breaker Panel to the Disconnect Box
Running the electrical from a breaker panel to the disconnect box can be done many different ways.

The location of the panel and the outside mini split location is always different.

The first step is to know the location the Mini Split will sit at.

The next step is to find the electrical panel which holds the breakers.

Most HVAC companies will install a breaker with the correct amps and run a new line to the Disconnect.

The right wire gauge and length will need to be bought.

For example, a 20 foot run will need enough wire to go the entire distance.

Conduit for the wire will also be needed with three main types, Liquid Tight, Steel Conduit, and PVC.

Each type works well and is often a personal preference on which to use.

When I install unit I almost always use liquid tight which is very flexible and easy to use.

The main goal of Conduit is to protect the wire from the elements.

Most of the time the Conduit is run along a wall but can be buried or run though the walls of some homes.

Whichever conduit is used most all are sized 1/2-Inch.

Liquid Tight Conduit on Amazon
Sealproof 1/2-Inch Flexible Nonmetallic Liquid-Tight Electrical Conduit Type B, UL Listed, 1/2″ Dia, 25 Feet

Wiring up a mini split unit is not difficult if you have some wiring experience such as hooking up a ceiling fan or electric water heater.

If in doubt be sure to call a professional.

Each wiring scenario from the breaker to the disconnect will be different.

Sometimes a home existing wiring can be tapped into and used depending on the scenario.

The wiring from the disconnect to the outside condensing unit is almost always the same.

This post is meant to give the basics of wiring up a mini split.

With the many mini split air conditioner heat pump available there is likely to be variations.

Be sure to always follow the instructions that come with your unit.



20 thoughts on “How To Wire Up a Mini Split Air Conditioner or Heat Pump

  1. Daniel

    What size wire you require to connect from the panel to the disconnect for a 24,0000btu mini splic ac? And what size breaker will it need

  2. Rick Hollenbach

    You drilled a 3+ inch hole under the inside unit. My installation will have the inside blower mounted on an inside wall, and 8 feet to the left is the outside wall where the outside unit is mounted. can the copper lines be run straight out the inside blower housing along the wall, till it gets to the outside wall hole, and there it gets fed to the outside unit? see drawing below.

    x…………………………………….inside blower
    outside hole

  3. Christina

    I have a pioneer 1800btu mini split it calls for a 20amp breaker do I need a single or double breaker? And if the double breaker is required how do I wire a double breaker with 12/2

  4. john wanes

    recently had my roof re-done and they disconnected the wires from the unit on roof to the breaker box they connected the white neutral back to the correct slot on the breaker box but connected the black hot wire to the ground and know my unit won’t turn on I disconnected the hot wire from the ground and connected to the correct
    slot but still unit won’t turn on did they fry the unit

  5. Einstein

    So I was dumb enough to wire up 240v to a 120v, I know I burned up the mother board. Did I possibly ruin any other parts of the unit? Any advice is much appreciated

  6. Kristin

    I’m pretty sure I messed up. At first I ran a 12/2 wire from the breaker box to the condensing unit and I was told to use a 10/2 instead. Is this okay? It sucks because I already buried the line in conduit. I have a Mr Cool DIY Mini Split 18,000.

    1. Platon

      The wire depends on the AMP the units requires. A 12/2 is perfectly fine for a 15amps, even a 14/2 would do.
      Here is the chart for Montreal, Canada.
      Nº 6 : 60 ampères, 240 volts,
      Nº 8 : 40 ampères, 240 volts,
      Nº 10 : 30 ampères, 240 volts,
      Nº 12 : 20 ampères, 240 volts
      Nº 12 : 20 ampères, 120 volts,
      Nº 14 : 15 ampères, 120 volts
      That said, I’ve seen 12/2 wire on 30AMPS breaker in old houses and nothing bad happened; the new standards are just very very conservative.

    2. John Harvey

      18,000 BTU only calls for 12/2 wire. It seems only when you jump up to 24,000 BTU you need 10/2 wire.

  7. Justin Saylor

    The hardware store only had a 30amp disconnect box (smallest) my unit is a 20 amp. Can I still use the 30 amp box?

    1. Don

      Ye i will work. A disconnect is just a manual shut off not a breaker.

  8. David Chamberlain

    Do all the Mr Cool units cone with the hole saw? Where did you get yours? What else might you be running simultaneously with the unit.
    Great video… sold me. Thanks.

  9. Crystal Tipton

    I bought a Mr. Cool 9000 btu mini split system. The manual shows for the outside unit 9k & 12K “Minimum Cross-Sectional Area of Power and Signal Cables” 15 amp 14 AWG. I have been looking at a lot of information but am not able to confirm what I believe to be the required wiring for the system. It is my understanding from the main breaker box to the cut off box I will need a 20 amp breaker and 10 gauge wire to the cut off box. The cut off box can be non-fusible as long as it has the disconnect. Then from the cut off box to the outdoor unit I will need 12 gauge wire. I want to be sure I have enough electricity but not too much. I have wired dedicated lines in my house for the stove, dryer and heater that are all 240v and the house has not burned down in the 12 years I have been living there. Thank you for any advice you can give.

    1. David

      As a general rule, this would be the set up for most mini splits:
      Dedicated circuit
      20 amp breaker in panel
      12/2 wiring in conduit (I prefer flexible)
      Outside shut off box adjacent to unit
      12/2 whip from shut off box to unit

  10. Avan

    My mini split says Maximum Over Current Protection 25A so will i need a 25amp breaker instead of a 20amp breaker?

  11. sauteed mushrooms

    Can you explain the knockout clamp connector you used? Was it like this: “”

    And if so, is the clamp portion with the two screws on the outside of the unit? How do you account for the space the clamp and screws take up?

    Also, I purchased some of the clamps that are in the above link and they seem to have a semi-sharp metal circle where yours appears to be smooth. I’m worried about that circle digging into the wire over time. I looked up and there is one that is smooth I can buy, but it says indoor use only ( “ )”

      1. sauteed mushrooms

        Ok, What about the space required for the connector you used. Did you just create a little “crater” (for lack of better term) in the wall for it to sit?

        Also, does that connector grab or clamp the wire to hold it in place?

        Thanks very much for your assistance.


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