In connecting a motor with a 120/240V supply using a single breaker, the minimum SJ cord size cannot be less than which gauge?

When connecting a motor to a 120/240V supply using a single breaker, it is crucial to adhere to the National Electrical Code (NEC) standards regarding conductor size. The size of the conductors affects both the motor's performance and safety during operation. In particular, for motors that draw significant current, the SJ cord must be of adequate gauge to prevent overheating and ensure efficient operation.

In this context, the correct answer relates to the need for an appropriate ampacity rating for the cord based on the motor's load and the breaker’s rating. The minimum SJ cord size required is 10 gauge, which is designed to handle the high current draw associated with larger motors. Using a 10-gauge cord provides sufficient capacity for the electrical load as well as ensures that the voltage drop across the length of the cord is minimized under load conditions.

This choice reflects the general practice of following NEC guidelines, which specify that larger conductors are necessary for motors to ensure safety and prevent potential electrical hazards. This is particularly important when dealing with motor applications where the starting current can be significantly higher than the running current, necessitating a conductor that can handle those surges without risk of damage.

Smaller gauges would not provide the necessary current-carrying capacity