You will most likely need a 15 Amp breaker for a 12000 BTU air conditioner, but it is best to do the calculations for your specific unit.
Air conditioners’ (AC) cooling capacities can be measured in a number of ways, but the most important thing is that it is appropriate for your space.
Another important consideration is finding the right size breaker for your air conditioner. 12000 BTU air conditioners vary from one model to the next and you need to be specific when calculating the maximum ampacity of your unit.
The difference between tons and BTUs in air conditioning
When manufacturers refer to the tonnage of an air conditioner, they are referring to the cooling capacity that the air conditioner has. The usage of the term ‘tons’ in this instance refers to a time when people used to use tons of ice to cool their homes.
However, in modern times, the tonnage of an air conditioner refers to its capacity measured in BTU. BTU, or British thermal unit, is used to express how much heat an air conditioner can extract from the air in a space and roughly 12000 BTU is equal to one ton.
What size breaker do I need for a 12000 BTU air conditioner?
As important as it is to find an air conditioning unit that has the right capacity for your space, whether that is tonnage or BTU, it is also important to install this air conditioner on a circuit breaker that is the correct size to handle the current draw of a 12000 BTU air conditioner safely.
Figuring out what size breaker you need for your 12000 BTU air conditioner can be a complicated process, because you need to be specific about your air conditioner’s requirements and specifications.
This means that although most air conditioners up to and including 12000 BTU models, can work on a standard 15 Amp circuit breaker, it is best to do the calculations for your specific model to ensure that you are not relying on averages incorrectly.
In order to figure out the amperage that your 12000 BTU air conditioner uses, you must first figure out the amount of watts and volts that the air conditioner uses.
An electrical multi-meter can be quite helpful in this process, but there are also other ways to figure out this information for your air conditioner, that will be discussed below.
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Once you have done all the calculations necessary, the only thing left to do is to ensure that you follow the NEC (National Electrical Code) 80 percent rule when you are choosing a breaker size based on your calculation.
How to find the wattage and voltage of your 12000 BTU air conditioner
The wattage and voltage are usually indicated on a name plate or manufacturer tag, which is a metal plate that is attached to your unit.
If you are lucky, this plate will include the maximum ampacity of your unit, in which case you do not need to worry about the wattage and voltage and you can just use the maximum ampacity to find the correct breaker size that you need for your unit.
You can also use your air conditioner’s BTU and EER-rating to calculate an estimated wattage if you cannot find or read your manufacturer’s tag.
For this, you need to divide the 12000 BTU by your unit’s EER rating to get an estimated wattage for your unit. This wattage and voltage can then be used to calculate the ampacity of your air conditioner.
How to calculate the ampacity needed for your 12000 BTU air conditioner
The biggest determining factor in what breaker size you need is the maximum ampacity needed for the current that your air conditioner draws. This means that you need to determine the ampacity for your unit.
If you cannot find the maximum ampacity on the manufacturer label and you do not have a multi-meter handy, you can calculate the ampacity by dividing your unit’s wattage by its voltage.
The NEC 80 percent rule for circuit breaker size
The work is not done when you have calculated the maximum ampacity for your 12000 BTU air conditioner.
In order to ensure that you can run your air conditioner safely on this circuit, you need to ensure that this ampacity is only 80 percent of the total amps that the circuit breaker can handle to protect it from surges.
This means that you can only use a 15 Amp circuit breaker if your 12000 BTU air conditioner has a maximum ampacity of 12 A or less. For units with a higher maximum ampacity, you can go up to a 20 Amp circuit breaker or higher.