For sizing wire and breaker, you need to divide the total watts by the voltage to get the amperage on the circuit. Depending on the ampacity of the breaker, each size of breaker requires a different wire size. As a result, you can select the appropriate breaker and wire size based on the amp requirements. How to Determine the Correct Circuit Breaker Size? The National Electric Code states that having a circuit breaker is a fundamental requirement. Using the appropriate breaker size is another recommendation made by the Institute of Electrical and Electronics Engineers (IEEE). Circuit breakers are a requirement for all electrical circuits in commercial, residential, and industrial settings. To avoid electrocution and the spread of electrical fires, this requirement is justified. However, you are not permitted to use any circuit breaker in any circuit. You must use the proper size in accordance with the electrical currents and appliance specifications to ensure safety. The circuit bre