What is the minimum size of the equipment grounding conductor that can be installed in PVC containing three 500 kcmil conductors for a 350-amp system?

To determine the minimum size of the equipment grounding conductor in a PVC conduit containing three 500 kcmil conductors for a 350-amp system, we need to refer to the National Electrical Code (NEC) guidelines. The NEC specifies that the size of the equipment grounding conductor must be based on the size of the largest ungrounded conductor, in this case, the 500 kcmil conductors, as well as the overall size of the system.

For conductors with an ampacity greater than 200 amps, the NEC provides tables that specify the minimum size for grounding conductors based on the ampacity of the circuit conductors. According to NEC Table 250.122, for conductors supplying a 350-amp load, the minimum size for the equipment grounding conductor is 3 AWG when copper is used.

This highlights the importance of following the NEC guidelines for proper grounding to ensure safety and efficiency in electrical installations. Therefore, the sizing calculation supports that 3 AWG is the appropriate minimum size for this scenario, aligning with the requirements to provide adequate grounding for a 350-amp system with the specified conductor sizes.