Wire Size and Breaker for Heat Pumps & AC units (Tonnage Chart)

The wire size and breaker for heat pumps and air conditioners (AC) vary based on the tonnage. However, one might wonder how many amp breakers you need for a heat pump. 

A split heat pump or air conditioner has two separate electrical circuits, one for the outdoor unit (condenser) and the indoor unit (air handler or furnace). The main electric panel contains two different amp breakers; one for the indoor unit and the other for the heat pump condenser or air conditioner. Manufacturers list the maximum breaker size on the data plate located on the side of both units. 

Keep reading to find out more information and what wire and breaker sizes are needed for your central cooling system.

How Many Breakers Will You Need?

It is essential to know how many breakers you will need for a split heat pump or central AC in the first place. A regular heat pump requires two dedicated branch circuits: the condensing or AC unit and the air handler. 

Given that information, the main power panel has two separate breakers for the air handler and the other one for the heat pump condenser. 

What Wire Size and Breaker for Heat Pump? (Tonnage Chart)

Depending on the size wire, you’ll need to find the breaker’s size, which gives you the specific rating. 

Not only that, but the amount of voltage the heat pump needs also determines the size of the breaker. 

If you are still unsure how to follow this guide, you can quickly look at the nameplate data on the outdoor unit. 

In return, it makes it much easier to determine what size breaker you need. 

That information also provides you with the maximum overcurrent protection or MOP rating. 

Let us say you have a 2-ton heat pump at home. If you have your average 240 volts 2 kW air handler, you will need a 30 amp breaker and a #10 electrical wire. 

Wire gauges are measured in diameter based on the American Wire Gauge (AWG) chart.

The outdoor unit should specify the MCA (Minimum Circuit Ampacity) and MOCP (Maximum Overcurrent Protection) on its plate. The minimum ampacity helps determine the minimum gauge wire you need to use.

Furthermore, we have provided tonnage table charts below if you are a visual person and need a better reference. 

Why is Wire Size Important?

The wire size is essential because an overload can occur if it is not sized appropriately. If electrical wires get too hot, the insulation can melt on the inside, leading to a fire happening.

For example, suppose you have a relatively large heat pump with 24,000 BTU, yet your wire is only a 12 gauge. In that case, this is a safety hazard.

Overload is one of the many possibilities if you don’t utilize the proper wire size, and incompatibility issues can be just as obvious. You can also throw unnecessary costs into the equation even more to the point.

For all these reasons and more, you’d want to adhere to a measure twice, cut once mentality, especially when safety and financial stability are the cost.

When calculating the wire size you need, don’t forget to determine the voltage drop and wire capacity. Voltage drop occurs across the length the electrical current has to travel. On a 240-volt circuit, the voltage drop should not exceed 3% or about 233 volts.

In other words, the wire is slightly larger than the electrical current rating. For a 35-amp breaker, the running amps should be around a maximum of 28 amps.

The amperage should not be greater than 80% capacity. Breakers trip at around 125% of the amperage, so why is wire size such a big deal? In most cases, it’s easier to replace a breaker than it is to pull a new wire. A wire with more electrical current than it’s rated for will get hot and trigger the breaker’s thermal switch to trip, even at normal operating ranges.

As circuit breakers age and wear out, the breaker tripping threshold erodes back toward 100% of the breaker amp load and maybe less. Replacing the breaker can be done relatively quickly.

In the photo example above, electrical requirements for this 3-ton American Standard unit require a minimum amperage rating of 25 Amps. Based on the above chart, this 3-ton air conditioner unit requires an 8-gauge wire and a maximum size of 35 amp circuit breaker.

Both the wire and breaker size fall within the parameters outlined above. Using a 30-amp breaker, 80% of the amps are 24 running amps. So, you could get by with a 30 amp breaker. However, I’d still recommend the 8-gauge wire.

A 25-amp breaker would likely trip frequently because the 80% rule allows 20 running amps. The maximum load the 25-amp circuit breaker can handle is 31.25 amps (125% of the breaker amperage), which is likely to trip the breaker frequently.

How Many Amps Does a Heat Pump or AC Use?

As we mentioned previously, it truly depends on the heat pump size. Here, we have created a chart to help you better understand based on 1 to 5 heat pump unit draws. 

This chart is based on a 230-volt and 16 SEER. One thing to remember is BTU / ((SEER*0.875) x Volt) = Amps.

Air conditioners and heat pumps are necessary equipment in many homes to make things comfortable. When wiring them, it’s crucially important to get things right for safety reasons and to reduce the number of electrical problems you’ll have down the road.

For a standard 3-ton residential air conditioner or heat pump, you’ll need a 20 amp breaker with 12-gauge wire. Air conditioners smaller than 3 tons often use a 15 amp breaker with 14-gauge wire, while larger units can use up to 60 amp breakers and 3-gauge aluminum or 4-gauge copper wire.

There are many variables to consider when choosing a breaker and wiring an air conditioner (AC) in your home. It can quickly become overwhelming if you’re inexperienced in this sort of thing. Below we’ll take a closer look at the different types of ACs, and heat pumps to help you choose the correct breaker and wire size.

Figuring out precisely how many amps your heat pump will use is a tricky question to answer. Different-sized heat pumps generally will provide you with varying amounts of amps used. 

Still, the easiest way to break down these numbers is to determine what type of zone you are using.

The amps will change because of the different units and measurements used and accounted for. However, the numbers do remain relatively the same. 

Given that information, a single-zone heat pump uses around 15 to 20 amps, while a dual or tri-zone uses 20 to 30 amps or more.

However, you may wonder what a single and dual-zone is in the first place. Let us break it down for you before we go any further. 

• Single zone: This heat pump uses the machine for one outdoor or single condenser to the indoor head.

• Multi-zone: As you may have already guessed, a multi-zone heat pump uses multiple indoor heads that connect to the outdoor condenser. These heads vary in size and create a comfort zone that allows you to cool or heat specific spaces within your home or area.

Is the Circuit Breaker Size Listed on the Data Tag?

If you are like me and despise doing math on your own to find out what breaker size you will need for your heat pump, the first place you want to check out is the data tag. 

Since tags provide a lot of information, you may be wondering if the breaker size is on it in the first place.

In that case, then yes, the right breaker size amount has been listed on the data plate. The information in itself would be on the side of the condenser. 

Some manufacturers provide minimum wire and breaker sizes, while others offer the maximum fuse or breaker size you can use.

It’s worth noting in that same regard that not all manufacturers are created equal, and as such, you may have additional steps and information to sort through to find that precious heat pump data tag. 

Doing a quick search on the manufactYou’ds website might yield the answers you are looking for a little shorter, but put in the extra effort to ensure you have the exact name, brand, and model before going on your journey for clarity.

How to Read the Heat Pump Label?

At first glance, sorting through the seemingly endless amounts of information displayed on the label may look daunting. 

Still, it gets much easier when you understand that most of it aren’t intended for your typical homeowner to grasp.

When looking at the label itself, only about nine of those labels may be of any use, assuming you are not a certified electrician anyway.

Below, we will go over each of those nine different categories and explain their importance to you and why you would need to have that information on hand in the first place.

1. Serial Number

While initiallIt’spearing to be a string of numbers, this sequence provides a few essential bits of information. 

Still, the most notable of them would be that most manufacturers offer the manufactured year your condenser here.

In most cases, that number is the first or second pair of numbers appearing in the sequence.

Still, some manufacturers use letters and numbers instead. Building-Center.org is a good resource for determining the age of your HVAC and other mechanical equipment.

2. Model Number

Making its grand appearance next would be the model number, which thankfully is made more evident than some other more reclusive bits of information we will go over. We can determine the size of your heat pump from the model number.

The model number allows us to glean the cooling capacity of this particular heat pump by using two specific numbers located in the middle of this string of numbers. 

These two particular numbers are always divisible by six. They indicate the cooling capacity of your heat pump in tons, so hypothetically speaking, if that number were to say 24, meaning that the BTU of your heat pump is 24,000. 

You’d want to remove the thousands portion of the number and remember that every 12,000 BTU of cooling capacity equals precisely 1 ton. This tells us that the hypothetical 24,000 BTU heat pump has a cooling capacity of 2 tons.

Usually, you can also estimate the SEER rating from the model number.

3. Whether or Not it is Factory Charged

On the smaller side of practical knowledge, but it is readily available as well, this line indicates whether or not your pump is using the old R-22 refrigerant, which is slowly pulled from circulation, or the newer, industry-standard R-410A.

4. Running Load Amperage, or RLA for Short.

In this part of the label, you get told just how many amps will be pulled when you initially start your compressor’s motor.

5. Locked Rotor Amperage, or LRA for Short

Here you’ll find just how much electricity is required to start the compressor. 

While it may seem unimportant initially, the number itself is needed to know just how much electricity you would need to run your entire system off of a generator should the need arise.

It’s imperative to note that you will need a generator that can handle several times the average current required to kick start things in the first place.

In most cases, five times the average generated amount is sufficient but refer to your owner’s manual for specific details regarding your heat pump.

Next, we will discuss the max breaker size for a heat pump or air conditioning unit.

6. Maximum Amp Circuit Breaker or Fuse Size

Finally, we come around to some static (no pun intended) consistent information, this indicates the maximum rating amount of electricity your amp circuit breaker can handle before tripping, and this number is always precisely double the amount of your RLA.

Fortunately, the label includes the maximum breaker size (or it may say max fuse size). Some manufacturers include this for both US and Canada. Often the US and Canada maximum breaker sizes are the same.

7. Date of Manufacture

Few times in life are the answers given to us quickly. When your manufacturer makes the heat pump, it can very well be handed to you on a silver platter without going through the tedious process of decoding those two seemingly random numbers in the serial number we discussed.

If you are lucky enough to have a heat pump with just such a label, count yourself lucky. This information is often located directly beneath a barcode for reference, but this may not always be the case. Most manufacturers insert the year in a two-digit form in the serial number.

8. Cooling Air Conditioner or Heat Pump

Even if you are a master electrician and can distinguish between the two with a passing glance, having the title given to you is always pleasant.

Here your labeling will tell you whether or not the unit you are looking at is an AC, or its slightly more energy-efficient cousin, the heat pump.

You can also peer inside the condenser to see if the reversing valve exists. If it has a reversing valve, it is a heat pump. Air conditioners do not have a reversing valve.

9. Name of the Manufacturer

Bringing things full circle, we come to the last bit of info required, and sometimes the easiest to establish, just who built the product you are looking at. 

Typically this is in tiny print and can either be the full name or something abbreviated, but you will have some indication as to who made the product here.

Circuit Breaker Requirements Based On Unit Tonnage

It is standard to measure air conditioner and heat pump size based on tonnage. When choosing a unit for your home, you’ll often see ACs and heat pumps ranging from 0.5 tons up to 5 tons, and sometimes even larger. But what exactly does it mean when an AC unit is “one ton,” and how does that help choose breaker size?

Regarding HVAC units, a ton refers to the amount of air a system can cool in a single hour. Regarding heat, one ton equals 11,917 British Thermal Units (BTU) per hour, often rounded to 12,000 BTU/hour. 12,000 BTU/hour can generally cool 500 to 600 square feet.

Now that you know a little about measuring air conditioner and heat pump capacity, let’s look at the common tonnages for these units and what breaker size each requires.

From the chart, we can determine that:

• a 2.5 ton heat pump breaker size is about 20 to 30 amps
• a 3 ton heat pump breaker size is also typically about 20 to 30 amps
• a 4 ton heat pump breaker size is also typically about 30 to 40 amps

Breaker Sizes for Different Size AC and Heat Pump Units

There are a wide variety of air conditioners and heat pumps on the market, so it should come as no surprise that there are many variables to consider when choosing a breaker size for your unit. There are three main types of air conditioners and heat pumps used in residential buildings:

• Central
• Mini-split
• Window

Each air conditioner type has different power requirements. Central systems often require the most power, while window units require the least.

Central Air Conditioners and Heat Pumps

Most modern homes built in the last few decades have a central air conditioning system or heat pump. A central system cools or heats air at a central compressor unit and distributes the cooled air throughout the residence through ductwork.

Central air conditioners and heat pumps are some of the largest units that you’ll find in a residential home. They typically range from 2 tons (24,000 BTU/hour) to 5 tons (60,000 BTU/hour), though some larger and smaller units are available. Most central units run on 220V or the equivalent.

The circuit breaker requirements for central air conditioning systems vary widely depending on the unit’s size. A typical central air conditioner or heat pump needs a breaker between 15 to 60 amps. Smaller 2-ton central units need a 20 amp breaker, while larger 5-ton units often require a 60 amp breaker.

The exact breaker size you need primarily depends on your air conditioner, so check the requirements usually printed on the compressor unit or consult the table above.

Mini-Split Air Conditioners and Heat Pumps

Mini-split air conditioners and heat pumps are very popular and excellent at cooling a relatively small space compared to a central AC system. Mini-split ACs have an outdoor compressor unit and an indoor evaporator unit, with refrigerant and electrical lines running between the two.

Mini-split air conditioners and heat pumps come in various sizes, but you can generally find units between 1 ton (12,000 BTU/hour) and 2 tons (24,000 BTU/hour). They don’t have nearly the capacity of a central air conditioning unit, but a 2-ton mini-split can cool areas up to 1,200 square feet. Most mini-split units run on 220V or the equivalent.

While there are small and larger mini-split units, most fall into 1 to 2 tons. Subsequently, you can use a 15 amp circuit breaker for most mini-splits, though you may need a 20 amp breaker for some of the larger units. You can often find exact requirements for breaker size printed on your mini-split compressor unit.

Window Air Conditioners and Heat Pumps

Window air conditioners and heat pumps are incredibly portable, easy to install, and energy-efficient, so it’s no surprise they are very popular. Most of the time, you’ll find a window unit set in a window opening and plugged into a regular 110V/120V outlet. 

Window units are some of the smallest air conditioners and heat pumps you can buy, excluding portable units. Window air conditioners and heat pumps can typically manage up to 500 square feet and range from 0.5 tons (6,000 BTU/hour) to 1 ton (12,000 BTU/hour).

With a power draw of about 4-8 amps, you don’t need a large circuit breaker for window units. A standard 15 amp breaker is sufficient for a window air conditioner or heat pump in almost every case.

Air Conditioner and Heat Pump Electrical Wiring Requirements

Equally important as choosing the correct breaker for your air conditioner or heat pump is choosing the correct wire gauge. You typically measure wire gauge according to the American Wire Gauge, often abbreviated to AWG.

Below is a quick reference table to help you decide what wire gauge is best for your situation based on your circuit breaker size:

The above table is by no means a definitive guide to which wire gauge you should use, but it is a good rule of thumb. If you’re ever unsure, avoid caution and use a larger wire gauge than you think you need to be on the safe side.

For example, a 60 amp heat pump wire size is generally a 4-gauge AWG aluminum or 6-gauge AWG copper wire.

Small mini-split systems and window units often require a 15 amp breaker, so a 12-gauge aluminum wire or a 14-gauge copper wire is usually suitable. Larger mini-split systems and central air conditioners or heat pumps utilize much larger breakers, so make sure to use an appropriately smaller wire gauge.

If you’re unsure whether the wire you’re using is copper or aluminum, look at its outer insulation, where it’s often labeled. You can also cut the ends of the wire to check it visually: copper wire is golden brown, while wire made from aluminum is dull gray. Always check the inside of the wire and not the outside to see past any coating or wrapping.

How to Find Your AC or Heat Pump’s Ideal Breaker and Wire Size

So far, we’ve discussed the general breaker and wire sizes that you should use for different air conditioners and heat pump units. But what about your specific unit and situation? Luckily, you can find this out pretty quickly with all of the above information and by looking at a label on your compressor unit.

1. Find Your Unit’s Minimum Ampacity – There should be a white label with black lettering on your air conditioner or heat pump’s compressor unit (the outdoor unit). Check the label to find your specific unit’s minimum ampacity. It’s often given in amps and labeled “Minimum Circuit Ampacity.”
2. Find Your Unit’s Maximum Ampacity – Look on your AC or heat pump’s compressor unit for the label to find the minimum ampacity. It’s often given in amps and labeled “Overcurrent Protective Device Max.”
3. Choose the Correct Breaker Size – Choose a circuit breaker that can handle more amps than the minimum ampacity but not one that’s over your unit’s maximum ampacity.

For example, suppose that a unit’s minimum ampacity is 42 amps and its maximum is 60 amps. In this case, you should use a 50 amp breaker because it is the next step above the minimum ampacity but still below the maximum ampacity. Use 6-gauge aluminum wire or 8-gauge copper wire.

Do AC Units & Heat Pumps Need 240 Volt Breakers?

Double-pole circuit breakers often look like two single-pole breakers fused. A double-pole breaker has two hot wires with one neutral wire. If either of the hot wires causes the circuit to trip, both switch off. A double pole breaker can handle two 120V circuits, but you use them more often for a single 220V circuit.

Most large air conditioning units and heat pumps run on 220V and require their circuit with a double-pole circuit breaker. Smaller window units can run on 120V, so you could put one on a single-pole breaker using only one of the hot wire slots.

What If You Don’t Use the Correct Size Breaker or Wire?

Now that you know a little about wiring air conditioners and heat pumps using the correct size wire and circuit breaker, you’re probably wondering: “What if I don’t do it right?” This question is a valid concern for many amateurs working on their home’s electrical, so let’s take a look.

Incorrect Wire Size

Choosing the correct wire gauge for the power going to your air conditioner or heat pump is crucial. It can get confusing if you’re not careful because lower gauge wire can handle more power than higher gauge wire.

Lower

Everything should be completely fine if you use a lower gauge wire for an air conditioner or heat pump. Using a lower gauge wire over a higher one is better because it can handle more current than necessary and keeps things running smoothly.

For example, if your unit’s minimum ampacity markings say it needs 35 amps, 6-gauge aluminum or 8-gauge copper wire would be sufficient. However, a smaller 4-gauge aluminum or 6-gauge copper wire would be fine.

Higher

Using a higher gauge wire for an air conditioner or heat pump can be catastrophic, and you should avoid making this mistake at all costs. A higher gauge wire that cannot handle the supplied current is a significant fire hazard.

For example, if a unit’s power needs require you to use an 8-gauge wire, but instead, you use a 12-gauge wire, it can cause severe problems.

Incorrect Breaker Size

Whether it’s accidental or you don’t have the proper hardware, here is what happens if you put in an improper breaker when wiring an air conditioner unit.

Lower 

If you install a circuit breaker with a lower amperage capacity than your air conditioner or heat pump requires, it can be a massive headache. While installing a lower amp breaker usually doesn’t present a safety issue, it will cause the breaker to trip nearly constantly.

For example, if your wiring and unit require you to install a 30 amp breaker, but you install a 20 amp one, it will continuously trip and make using your air conditioner nearly impossible.

Higher

Using a higher amp breaker than the recommended size can cause serious problems. It will allow more power than expected before tripping, causing your wiring to melt and potentially start a fire. However, things should be fine if your wiring is the correct gauge to handle the power and your unit has built-in overcurrent protection.

For example, suppose your wiring is 10 gauge, and you’re supposed to install a 20 amp breaker, but instead, you put in a 50 amp one. The wiring is not strong enough to handle the added current and can be a severe fire hazard.

Conclusion

Understanding the intricacies of your HVAC system, the wiring, and the subtle other nuances that make it work can be complicated and far too much work for some people. 

If you ever feel overwhelmed or out of depth, consider consulting a professional for more in-depth guidance.