Air conditioning circuit breaker, how to choose?

When we talk about air conditioning installation we must also remember the electrical part, which is essential for its perfect functioning. It is necessary to correctly dimension both the cables and the circuit breaker for the air conditioner.

The World of Electrical teaches in this article how to calculate the appropriate circuit breaker to be used in air conditioning, be it Split, portable, inverter or any other air conditioning model. Also learn the correct procedure for dimensioning the air conditioning circuit breaker according to the standards. Come on guys!

When doing the electrical installation of an air conditioner we must be aware of the characteristics of the air conditioning and the electrical installation. Regarding the electrical installation of the air conditioner, it is necessary to evaluate some important items, such as mains voltage, operating voltage of the air conditioner, where it will be installed, cable section and which circuit breaker to use.

Air conditioning circuit breaker: Why use it?
The circuit breaker is a mandatory component and serves to protect circuits from electrical failures, such as short circuits. Thus, when a power failure occurs, the circuit breaker trips automatically.

Because the air conditioner has a relatively high power consumption, it needs an exclusive circuit breaker, which ensures the selectivity and safety of those in the electrical circuit.

Air conditioning circuit breaker: Which to choose?
Regarding the air conditioning circuit breaker, there are some tables for air conditioning circuit breaker, according to their respective characteristics. In these tables, each circuit breaker has a nominal current defined according to the power of the appliance to be connected. It is important to clarify that some manufacturers of air conditioners indicate in the manual or on the label of the condenser which the current for each air conditioner.

Learn to size circuit breaker for air conditioning.
Which circuit breaker to choose for air conditioning?

In cases where the manufacturer does not indicate the electrical current consumed by the air conditioner, it is necessary to calculate its current using its electrical power. Remember that the electrical power (watt) is different from the cooling power (BTU), so we cannot convert the cooling power into electrical power to size cables and circuit breakers. This is because the ability to transform electrical energy into refrigeration energy depends on the air conditioning model and technology involved in the construction of each appliance.

As an example, we will use a split inverter air conditioner of 11,000 BTU, 1,200 W and with a 220V supply voltage. The first step to do the calculation and find the electric current of the air conditioner is to divide the electric power by the electric voltage so that we can find the electric current value. See the image below on how to perform the calculation correctly.

Learn to a size circuit breaker for air conditioning.
Resolution for calculating electric current.

After calculating the nominal current of the air conditioner, we need to multiply its nominal electrical current by the service factor, which is equal to 1.25. This service factor is a safety margin so that the circuit breaker does not trip and disconnect the circuit when the air conditioner is in operation.

Learn to a size circuit breaker for air conditioning.
Resolution applying the service factor.

When multiplying by the service factor, the final electrical current is 6.81A, with the electrical current used as a reference for dimensioning the air conditioning circuit breaker. In addition to knowing the rated current of the circuit breaker, it is necessary to have knowledge about the circuit breaker curves, that for air conditioning we use a C curve circuit breaker.

The ideal circuit breaker is the one that has the current closest to the reference current, which in this example is 6.81A. According to the following table, there is no circuit breaker with a current of 6.81A, so we selected a circuit breaker for the air conditioner with the current value above the current reference value for the dimensioning. So we need a 10A bipolar circuit breaker with a C curve.

Learn to size circuit breaker for air conditioning.
Table for circuit breakers with two poles.

Air conditioning circuit breaker: Final considerations
We recommend that you read the air conditioning installation manual before starting the dimensioning or installation of the circuit breaker. When the manufacturer does not provide the data on which circuit breaker to use, he recommends the professional responsible for the installation to consulting the NBR 5410 standard.