What is the minimum size EGC when supplying a 3 hp motor from a 1-pole breaker with maximum size nontime-delay fuses?

To determine the minimum size Equipment Grounding Conductor (EGC) for a 3 hp motor supplied from a breaker, it is important to consider the National Electrical Code (NEC) guidelines for grounding conductors.

For a 3 hp motor, first, you need to find the full-load current, which you can do by referring to NEC Table 430.250, which lists the full-load current for different horsepower ratings. Typically, a 3 hp motor at 240 volts would have a full-load current around 15 amps.

Next, the NEC provides guidelines for the sizing of grounding conductors based on the feeder or branch circuit conductors. When you use the chart in NEC Table 250.122, the EGC size is determined by the rating of the overcurrent protection device (such as a breaker or fuse) protecting the circuit.

If you consider a 15 amp breaker or a 20 amp breaker for this motor application, the corresponding minimum size for an EGC would follow the appropriate values given in the NEC. According to this table, for equipment that is protected by a 15 amp or larger circuit, an 8 AWG copper EGC is typically required.

Choosing the correct minimum size for the