The Complete Guide to Wire Gauges / AMP Ratings for Package Terminal Air Conditioners

Home » Knowledge Base » The Complete Guide to Wire Gauges / AMP Ratings for Package Terminal Air Conditioners

When it comes to wire gauges and AMP ratings for your PTAC unit, size is an important consideration.

Every unit has an amperage (AMP) rating. AMPs are the units used to measure electric current, and higher amperage ratings require larger wires. If the wires are too small for the amperage rating, excess heat can destroy them and pose a dangerous fire hazard.

How do you determine the correct wire gauge for 30 AMP units, among the others? We’ll take a closer look at everything you need to know in this guide.

What is a Wire Gauge?

Gauge is a standardized method of measuring a wire’s diameter. A wire’s gauge is what determines exactly how much electricity can flow between the circuit breaker and the appliance.

Why Does the Wire Gauge Matter?

With any electrical project, it’s incredibly important to understand just how dangerous it can be to use a wire gauge that’s too small. The smaller wire can’t conduct the higher amperage properly, leading to excess heat in the wire. This excess heat can destroy the wire itself, damage the PTAC unit, or even cause a fire. Your circuit breaker simply can’t offer enough protection

The chance of a fire or other electrical problems is commonly increased by plugging high AMP appliances into strips or extension cords that have a lower wire gauge. Never plug your PTAC unit into a low-gauge extension cord or power strip. If you can’t avoid using one in your home, take the time to purchase one that matches or exceeds the AMP rating of your PTAC unit. Taking proper precautions now could save you later on.

Choosing to use a larger gauge than the AMP rating calls for isn’t dangerous, but you might find it inconvenient. Higher gauges are bulkier, stiffer wires that aren’t easily hidden or manipulated. When the PTAC unit is in your home, work with a lighter wire for convenience and aesthetics.

How are Wires Sized?

A quick walk through the electrical department of your local hardware store will highlight just how many sizes of wires are available. While it may seem overwhelming at first glance, the American Wire Gauge (AWG) system has standardized wire sizing, making it simple to find what you need.

When it comes to wires, a higher number means a smaller wire diameter. So, an 18-gauge wire would be much thinner than a 6-gauge wire.

Understanding Labels

The labels on your various cables can be confusing, as they often describe elements beyond the gauge of the wire itself.

The first thing you’ll notice is a number—this is the gauge of the wire. Next to that number, there might be an additional number, which indicates the number of conductive wires in the cable.

Finally, the label might include “G,” which indicates that the cable contains a grounding wire. The ground wire isn’t included in the number of conductive wires.

As an example, if the label says “10-2G,” that indicates that the cable is 10-gauge wire with two conductive wires along with a grounding wire.

What Size Do I Need?

Chances are, your PTAC unit will have an AMP rating of either 15, 20, or 30. This information will be printed on the information panel somewhere in your unit, along with the correct wire gauge.

This chart outlines the AMP rating and the necessary corresponding wire gauge:

AMPsWire Gauge
10 AMPs16-gauge wire
15 AMPs14-gauge wire
20 AMPs12-gauge wire
30 AMPs10-gauge wire

For comparison, your average table lamp is 10 AMPS and only requires an 18-gauge cord. On the other end of the spectrum, large electric furnaces and heaters are 60 AMPS and require 4-gauge cords. The most common gauges are 2, 6, 8, 10, 12, and 14, but you can still find them in other sizes.

These ratings are only for standard wires, which are typically made of copper or other non-metallic metals.

A Note About Your Circuit Breaker

While determining the correct wire gauge is essential, it’s crucial that you know your circuit breaker’s draw before buying your PTAC unit. For instance, you can’t install a 30-AMP unit if your circuit breaker only allows for 15. Your circuit breaker would require extensive rewiring to increase the AMP rating to accommodate the new unit.

The opposite scenario is much easier to handle. If you have a 30-AMP circuit breaker but want to install a 20-AMP unit, the wire will still be able to handle that level of an electrical draw. However, you will need to change the circuit breaker and the outlet for your new unit.

What Else Should I Consider?

In addition to the wire gauge, there are a few other characteristics to keep in mind when selecting wire for your PTAC unit.


Most—but not all—wires are made of copper, silver, or brass. If you use a cord made from a different material, do some extra research to see if you need a different gauge than what’s considered standard. It’s important to familiarize yourself with the right numbers for your cord to reduce the risk of overloading the wire.


In some cases, the length of your cord may affect the gauge you need to use. This is particularly true if your PTAC unit is more than 100 feet from the plug, or if the cord is going to be clustered among many others.

Solid or Stranded

Some wire is stranded, or woven, which can facilitate a better electrical pull than solid wire. However, solid wire is considerably easier to work with and is commonly found in many household cables.

Final Thoughts

Choosing the correct wire gauge for the AMP rating of your PTAC unit will help keep your unit running at peak performance while reducing the risk of a fire. If you have further questions about the safety of the electrical work for your PTAC unit or around your home, consult an experienced electrician who can personally evaluate and advise you on the situation.

Want more insight and advice on purchasing and installing PTAC units? Contact us today and let us know how we can help.

Leave a Comment