Circuitry & Wiring Specifications for Installing Ductless Mini-Splits & HVAC Units

LG Ductless Mini-Split

LG LS120HEV1 12000 BTU Mega Series Single Zone System with Heat Pump

Ductless mini splits are one of the most popular AC choices for homeowners and businesses alike. We sell tons of mini split air conditioners each day on our website, and, on our blog, have previously written about all the benefits of and features to consider when purchasing a mini-split AC of your own.

Installing ductless mini splits requires a high level of electrical knowledge in order for the job to be done safely and without harm to yourself or the unit. For that reason, we do not recommend homeowners try to install the unit themselves. Unless you are an advanced DIYer with extensive experience in electrical work, we strongly advise you hire a professional to get the job done.

But even professionals have to learn the ropes, and so if you are an electrician who simply has not undertaken a mini split installation project before, this post is for you. Here, we offer a step-by-step guide to everything you need to know about the electrical specifications for installing ductless mini splits.

NOTE: These instructions are in regards to electrical specifications only, and do not include line set installation or refrigerant set-up.

 

Step 1 – Mini-Split Shut-off box:

Run a 230/208 volt or 115 volt* dedicated line from the main break box to the area where the shut-off box will be installed next to the unit.

* Voltage depends on the system. The vast majority of mini-split units are 230/208V, but there are some that are 115V.

Step 2 – Mini-Split Wiring:

Mount the shut off box on the outside wall and connect the wires from the break box.

Electrical Shut off box

electrical shutoff box detail
208/230 Volt Shut Off Box

In order to meet code, you must have a shutoff box at the location of the unit. This makes system repairs safer and easier. Wire the two hot leads to the fused connections in the box and the ground to the provided connection. Then, reattach the faceplate and insert the on/off switch. It should be kept in the off position while you continue to work on the unit.

Step 3 – Electrical Wire Whip:

Attach an electrical whip to the shut-off box and run it to the unit.
Electrical Whip
An electrical whip is a premade, outdoor grade wire set that is intended to run from a shutoff box to the unit being installed. Using this ensures that you will have no issues with meeting code and keeps the process simple for you. The whip must be wired into the shutoff box and then to the unit as we will talk about next.
Alternatively, run your own wire through an outdoor grade conduit so that is protected from the elements. (an electrical whip is simply a pre-done version of this.)

 

Step 4 – Mini-Split Wire Connection to Base:

Connect the wires to the unit based on the instruction manual.
IMG_7004
While it might be difficult to see through the other wiring in the unit, here we have included a picture of the main power connections to a Friedrich Mini Split Unit. You can see the green, black, and red wires connect the terminal blocks on the bottom right. The exact details of a connection like this are specific to your unit. Always reference the instruction manual before attempting any electrical connections.

LG Wiring Diagram

Step 5 – Mini-Split Wiring Connecting Inside to Outside Unit:

Connect the wire for the indoor unit to the outdoor unit.
Mini Split Wiring
Depending on whether you are installing a single zone or a multi-zone unit, you will have a different number of connections. This Friedrich multi-zone unit has connections for 4 units, all of which are numbered for easy cross-referencing to the indoor unit. Make sure to write down which wire color is connected to which number. It is also critical to make sure that each indoor unit on a multi-zone system is wired to the same input that its line set is connected to. Otherwise, the system will not operate correctly.
It is recommended to use 14 gauge stranded wire for installation. Pictured is 14 gauge solid wire which will work, but should only be used if stranded wire is unavailable. Total Home Supply offer Honeywell 14/4 Mini Split wire in 50 ft and 250 ft rolls.

Step 6 – Mini-Split Installation Complete:

Run the wire inside.
Indoor Mini Split Electrical
Just like the outdoor unit, the indoor connections must be made in the correct order. Connect the 3 main wires along with the ground to their respective terminals. Some manufacturers recommend using round crimp style terminals for a more secure connection.

After this, the electrical portion of the installation is done! Congratulations!
2015-07-28_2006

If you have any further questions regarding the electrical specifications of installing ductless mini splits, please do not hesitate to contact us at 1-877-847-0050 and speak to one of our qualified representatives.

Ready for the next step? Check out our multi zone mini split buying guide!

Kristen Turner

Featured blogger for Total Home Supply.

18 Comments

Rene

about 4 months ago

Great information but I have a question. I'm installing 2 multi split system in my house. The condenser requires a 30 amp breaker. It also calls for 12-3 cables from the outdoor condenser to each unit. But my question is, what wire do I need to run from the main panel to the outdoor box since I'm installing 2 multi split systems?

Reply

Mickey Luongo

about 4 months ago

Depending on the distance from the panel to the unit you would want to use 10/2.

Reply

Rene

about 4 months ago

So a 10-2 outdoor cable, is that for each disconnect box or is the one cable enough to power both systems?

Reply

Mickey Luongo

about 4 months ago

You would need one 10/2 wire, an independent breaker, and a disconnect box for each outdoor unit.

Reply

Tim Maddison

about 4 weeks ago

If the units are co-located and serviced by the same disconnect, can't you run a single 40A , 10 AWG circuit to the disconnect?

Mickey Luongo

about 4 weeks ago

It is not advisable and probably against code to have two units running on the same disconnect.

Maria Flores

about 4 months ago

Our electrician says he will install 220v for our 230v/208v mini split. He says 220 and 230 are the same. Is this accurate?

Reply

Mickey Luongo

about 4 months ago

Yes, they are the same.

Reply

Jason

about 2 months ago

If my split system is 220 v how do I connect it to my 110 V supply? is there a transformer in the unit? Do I need to buy a transformer?

Reply

Mickey Luongo

about 2 months ago

You cannot connect a 220 volt product to a 110 volt power supply.

Reply

Jesse

about 2 months ago

Please help anyone who might know. I need a dual zone mini split unit the is only 115 volts. This is for a disaster relief trailer we are building for Tyson foods. We are limited to 115 volt power supply. Any suggestions are welcome.

Reply

Mickey Luongo

about 2 months ago

Unfortunately, none of the major manufacturers make a multi-zone unit that is 115 volts. You could use two single zones instead.

Reply

Jason Smith

about 2 months ago

I am planning on using dedicated 6-3 UF wire w/ 50amp breaker to exterior 30amp-rated condenser a a 4-zone system with disconnect then 12-2 from condenser to each indoor handler. Question is, would i have to pass all 4 12-2 wires through conduit into soffit and then unto rest of the house?

Reply

Mickey Luongo

about 2 months ago

Unless your unit calls for it, 12/2 it is overkill for going from the outdoor unit to the indoor units. Most brands require 14/4. Depending on code in your area, you should not need to run the wire through conduit unless this is a commercial installation.

Reply

Aaron

about 3 weeks ago

What size break will I need on my 10-2 wire for a 230V mini split.

Reply

Mickey Luongo

about 3 weeks ago

Check the specs of your mini split. It will tell you what size breaker is required.

Reply

andy

about 2 weeks ago

Hello I has Air conditioner Panasonic 208/230V. My house has 120V how to do 230V Please help me. Thank you

Reply

Mickey Luongo

about 2 weeks ago

Every home has the option of using 208/230 volt. Contact an electrician for more details.

Reply

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