Mini-Split Wiring Guide

Mini-Split Wiring Guide

What You Should Know About Mini-Split Wiring

Ken, the eComfort Product Expert
Product Expert

Ductless mini splits are one of the most popular and energy-efficient choices for homeowners and businesses.

This “split” system consists of an outdoor unit containing the condenser and compressor, and the indoor unit which supplies the conditioned air.

Although they are easier to install than central air conditioning, they are not “plug ‘n play” like window units. Mini split systems require a dedicated electrical line into the building’s electrical panel.

Here’s what you should know about mini split wiring in order to ensure a worry-free system for years to come.


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Electrical Service

expert ac contractorThe electrical service panel supplies power to the outdoor unit. For safety, it utilizes a disconnect box and surge protector via electrical wires contained in a weather-proof cable called a whip. 

Depending on the size and model, mini splits have specific power requirements. Some small 9k - 12k BTU systems may require a 110-volt service, but most will require 220 volts or more. Since these systems need to be hardwired into the electrical service panel, be sure the breaker panel is properly sized and can handle the additional voltage.

We recommend that you consult with a professional installer to help with the electrical requirements of your system and ensure the work is done to code, maintaining the warranty of your mini split system.


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Wire Gauges

[wire tools]rightMini split systems have specific wire gauge (thickness) requirements and the difference between the right and wrong electrical wire can be dangerous. 

When shopping for connecting wire, be sure to get quality wire that is the proper gauge. Also, look for connecting wire that is rated for sun exposure and "UL-listed." This signifies that the product has passed safety tests performed by Underwriters Laboratories.

Common wire sizes include 16, 14, 10, 8, 6, and 2-gauge wire. The thickness of the wire determines the amount of current that it can handle safely.

The higher a wire's gauge, the thinner it is and the less current it can handle. Similarly, lower gauge wire is thicker and can handle more current. For example, #2 wire can handle 100 amps, while #16 wire can only handle 13 amps. Make sure your installer confirms the wire sizing because other factors, like length, will also affect the selection. 

The table below lists common household items by the amount of power they use with the appropriate size wire.


Wire Use Rated Ampacity Wire Gauge
Extension Cords 13 Amps 16 Gauge
Light Fixtures, Lamps, Lighting Runs 15 Amps 14 Gauge
Receptacles, 110-volt Air Conditioners, Sump Pumps, Kitchen Appliances 20 Amps 12 Gauge
Electric Clothes Dryers, 220-volt Window Air Conditioners, Built-in Ovens, Electric Water Heaters 30 Amps 10 Gauge
Electric Stoves 45 Amps 8 Gauge
Electric Furnaces, Large Electric Heaters 60 Amps 6 Gauge
Electric Furnaces, Large Electric Water Heaters, Sub Panels 80 Amps 4 Gauge
Service Panels, Sub Panels 100 Amps 2 Gauge


Electrical Whip

electrical whipPower whips are located outdoors and contain high-voltage wires concealed in a weatherproof enclosure that protects them from rain and sun exposure.

They are used to connect the 120v/220v power from the disconnect box to the outdoor condensing unit.


Disconnect Box: Fused vs Non-Fused

disconnect boxYou might be wondering, "Do I really need a disconnect?" All mini split systems require a dedicated circuit to supply power to the system.

disconnect box is required by code to be installed near the outdoor unit and allows for a technician to shut off power to the system when performing any service or repairs.

A non-fused disconnect box is preferred over fused. One reason is that the breaker in your service panel already provides the built-in protection in place of a fuse.

Another is that circuit breakers can be reset after they are tripped, while fuses must be replaced. Fuses can also corrode in the elements - rendering the system unsafe. Finally, fuses can be hard to find, and most people aren't comfortable replacing them.


Protecting Your Investment

lightning strikePurchasing heating and cooling equipment is a large investment. While manufacturers offer excellent warranties that cover manufacturing defects, they may not cover damage from electrical surges.

Surges can be caused by lightning or irregularities in your power delivery and could damage your mini split system's electrical components.

For such events, you will want the peace of mind that comes with a surge protector.

Rather than scrambling to replace your mini split system out of pocket after a damaging surge, use an HVAC device to provide your heating and cooling equipment with both exceptional protection and additional warranty coverage. 

Don't remain at the mercy of Mother Nature or your electrical company, install a surge protector and enjoy unparalleled peace of mind.


Connecting Cable

connecting wireAlso known as 4-conductor cable, connecting cable is electrical wire that supplies power and carries control information between the indoor unit(s) and the outdoor unit.

Typically, connecting cable is run through conduit in accordance to local codes. Most systems use a 14 AWG 4-conductor stranded cable, also written as: 14/4.


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Ken, the eComfort Product Expert
Product Expert
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