What is the minimum size equipment ground required for a 5-hp, 3 phase, 208-volt motor?

To determine the minimum size equipment ground for a 5-hp, 3-phase, 208-volt motor, it's essential to refer to the National Electrical Code (NEC). According to NEC Table 250.122, which outlines the minimum size of equipment grounding conductors based on the rating of overcurrent protection devices, we find the requirements for grounding motors.

For a motor rated at 5-hp with a 3-phase power supply, the NEC recommends using a specific size of equipment grounding conductor based on the ampacity and the rating of overcurrent devices. The minimum size of the equipment ground for this motor setup typically corresponds to the requirements for motors of similar ratings.

Calculating the full-load current of a 3-phase motor rated at 5 hp at 208 volts helps confirm the grounding requirements. For a 5-hp motor, the full-load current is generally around 15-17 amps, allowing for accurate reference to the NEC table. In this case, the equipment ground conductor required is 10 AWG copper, which can safely handle the potential fault current and minimize the risk of electrical shock or fire hazards.

This choice meets the NEC guidelines for safety and provides adequate protection for the equipment and personnel involved. Therefore,