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What Size Wire and Breaker for Ac? (Quick Answers)

The right size wire and the breaker is essential for ac as the wrong ac breaker and size wire will damage electric circuits. 

Hence everyone has to know what size wire and the breaker are necessary for an ac unit but sadly, not everyone knows how to choose the right size wire and breaker for ac.

Breaker & wire size for ac

Most air conditioners need wires that range in size from 18 AWG to 10 AWG. Even thicker wires, such as 8 AWG or even 6 AWG, are needed for larger 5+ ton AC units. Breaker sizes available for air conditioners are 15, 20, 25, 30, and 35 amps. Breakers up to 65A are needed for larger than 5-ton units.

Bear with us to find out the detail information regarding wire and breaker size for your air conditioner –


The wire size is crucial because if it is not sized properly, an overload may result. Electrical wire insulation may melt internally if they become too hot, causing a fire. Consider a large heat pump of about 24,000 BTU, but the wire is just 12 gauge. 

This poses a risk to safety in that situation. If the incorrect wire size is used, overload is one of the potential outcomes, and compatibility problems can be very obvious. 

The rule of thumb “measure twice, cut once” should be followed especially when safety and financial security are at stake. 

Remember to account for the wire capacity and voltage drop when estimating the required wire size. Voltage drop happens over the entire distance an electrical current must travel. 

The voltage loss on a 240-volt circuit should not be more than 3% or approximately 233 volts. Replacing a breaker is simpler than pulling a new wire. 

Even at normal operating ranges, a wire carrying more electrical current than it is rated for will become hot and trip the breaker’s thermal switch. 

The breaker tripping threshold degrades back toward 100 percent of the breaker amp load and less as circuit breakers get older and start to wear out. The breaker may be replaced fast.


A built-in safety switch in a home’s electrical system is called a breaker. Any component or equipment that is using too much power will have its electricity cut off by this switch. By doing this, an electrical overload that can result in an electrical fire is avoided. 

If the AC is drawing more amps than the circuit breaker is designed to manage, the circuit breaker will trip. The AC unit has two breakers: one that operates on the inside and one that operates on the outside. 

Finding the breaker’s size, which provides a particular rating, will depend on the size of the wire. Additionally, the size of the breaker depends on how many voltages the heat pump requires. 

The circuit breaker may have loose wires, the device itself may be malfunctioning and need to be replaced, or it may just be a straightforward electrical problem that could be the reason for frequent circuit trips. 

The circuit breaker’s capacitor may also degrade over time due to use. However, a lot of money is not needed for fixing this; it is a simple fix. A breaker can be used with more capacity than is required. 

On the outside unit, the nameplate information is easily accessible. In return, it makes figuring out what size breaker is needed much simpler. Depending on the manufacturer and model, there are several breaker sizes and wire gauges.

Residential systems frequently have a 5-ton or 60,000 BTU restriction.

10/2 or 10/3 wire for air conditioner?

Compared to a 10/3 wire, a 10/2 wire is the better option for an air conditioner. A hot #10, a neutral #10, and a ground #10 make up the 10/2 wire. Two #10 hots, one #10 neutral, and one #10 grounds are included with the 10/3. 

The ground would be the insulated green, neutral the insulated white, and heated the insulated black. A power cord is another term for these wires. The quantity of current flowing through the conductors is where the two options most significantly diverge. 

Since standard air conditioning units are single circuit appliances, technicians frequently use 10/2 wire size. The wire size is ideal since it can carry both the AC’s heating and cooling elements. The 10/3 wire, on the other hand, is designed for dual voltage equipment.

What type of circuit breaker for air conditioner?

Almost every delicate electric device requires a circuit breaker. Circuit breakers save the home appliance from any sort of devastating accident caused by a high flow of electricity. 

As an air conditioner is a delicate electric device that needs a high electricity flow, it will require a circuit breaker.

You need to see the Horsepower of the AC:

Generally, air conditioners that are found in markets have a horsepower of around 1/2 HP to 2.5 HP. These types of air conditioners need a 30A circuit breaker. You can do easy math to find out what type of circuit breaker your air conditioner may need. 

You may know that 1HP is equal to 746 Watt. Here the formula for finding out the amperage of your circuit breaker is the Horsepower is multiplied by 746 and then divided by the voltage of your area. 

And then multiply the whole number by 250%. By doing so, you may get the number for your circuit breaker. Remember one thing, a different place has different voltage requirements, so if you are living in an urban area then the voltage may vary. 

The Voltage of Your AC is a matter of concern:

As we have talked about earlier, Air conditioners have different voltage requirements. Like 400 kilovolt systems, it needs a 10% more powerful circuit breaker than the usual circuit breaker. For 120V it needs to have a single-pole breaker. 

Generally, a two-pole breaker is required for home appliances. For central air conditioning, it requires 200 to 240 volts.  

Proper Circuit Breaker is Required to Protect from Short Circuit Issues:

The circuit breaker is used so that home appliances or any electronic machine don’t have to burn down or fall apart. Sometimes high voltage electric machines blow and cause fire. 

That’s why air conditioners may require 15A, 20A, 25A, 30A, and 35A air conditioners. For a bigger air conditioner, you may need bigger circuits which are 65A to higher Ampere.

How to calculate cable size and breaker for ac?

The following steps will certainly help you to calculate cable size and breaker for ac –

Determine the load which is measured in Ampere (Amp):

Identifying the load in terms of electric current is the first step in determining the wire size. The current going through the cable for appliances like fan motors and pumps is the same. However, it differs dramatically for air conditioners.

Establish the size of the circuit breaker:

Determine the size of the circuit breaker next. Take the maximum current of the air conditioners and divide it by 80% to determine the appropriate circuit breaker size. The size of the circuit breaker that is next in line will be the one needed.

Determine the wire size based on the current-carrying capacity:

Identify the corresponding wire size by current-carrying capacity using the circuit breaker ampere. Any wire current-carrying capacity table based on preference and practicing standards can be used.

Examine the Voltage Drop Percentage:

To ensure that air conditioners and other equipment won’t experience low voltage issues, the voltage drop must be verified to see whether it is within an acceptable percentage after determining the wire size based on the current-carrying capability. 

The voltage at the beginning and end of a wire is not the same because wires have resistance. A voltage drop across the wire might reduce a 415V power supply to only 400V when it reaches the air conditioner. The wire length must be determined to assess the voltage drop. 

Find the voltage drop value using the wire voltage drop chart to determine the percentage of voltage drop again based on preference and practicing standards.

Examine the Correction Factor:

When sizing cables that will eventually be deployed in locations where the ambient air temperature will either be above or below 30°C, a correction factor must be applied. 

Multiplying the current-carrying capacity by the correction factor will apply the correction factor.

Final Thoughts

AC requires wires to be in the 18 AWG to 10 AWG size range. For sizable AC units that weigh more than five tons, wide wires like 8 AWG or even 6 AWG are necessary. For air conditioners, breaker sizes of 15, 20, 25, 30, and 35 amps are at hand. For 5+ ton equipment, breakers up to 65A are required.