In a 3-pole, 15-amp circuit breaker to a motor, if 10 AWG conductors are installed due to voltage drop, what is the smallest size equipment grounding conductor that can be used?

In the context of determining the appropriate size for an equipment grounding conductor (EGC) in a circuit with a 3-pole, 15-amp circuit breaker supplying a motor, it is essential to understand the relationship between the size of the overcurrent protection device, the conductor sizes, and grounding requirements.

When a specific conductor size, such as 10 AWG, is used for the circuit conductors, the National Electrical Code (NEC) provides guidelines for sizing the grounding conductor based on the size of the overcurrent protective device as well as the size of the main conductors. In this case, the circuit breaker is rated for 15 amps, and since 10 AWG is being used for the circuit conductors, it is permissible to use a grounding conductor that is also 10 AWG.

Specifically, the NEC allows for the use of the same size equipment grounding conductor as the circuit conductors when the conductors are part of a larger system and the overcurrent protection is at or above the minimum size requirements established by the code. Therefore, selecting 10 AWG for the equipment grounding conductor aligns with the requirements for systems where conductors are sized based on voltage drop or other factors, ensuring safety and compliance with code