What is the maximum rating of a receptacle that can be used on a dedicated branch circuit connected to a 40-A circuit breaker?

In determining the maximum rating of a receptacle that can be used on a dedicated branch circuit connected to a 40-A circuit breaker, it's important to understand the National Electrical Code (NEC) guidelines regarding the use of circuit breakers, conductors, and receptacles.

According to the NEC, the general rule is that the rating of the receptacle should not exceed the rating of the circuit breaker protecting the circuit. However, there are specific conditions in which receptacles can be rated up to a certain percentage of the circuit breaker’s capacity.

In this case, a 40-A circuit breaker can support receptacles rated for 40 amps. Additionally, the NEC allows for receptacles at 50 amps to be connected to a circuit with a 40-A circuit breaker given appropriate conditions are met, such as using the correct sized conductors to match the circuit.

Thus, using either a 40-A receptacle or a 50-A receptacle is permissible under these conditions. Therefore, the maximum rating of a receptacle that can be used on a dedicated branch circuit connected to a 40-A circuit breaker is correctly identified as either 40 amps or 50 amps.