For a 3-phase load connected to a 600-A circuit breaker with three 350 kcmil conductors in each run of RMC, what is the smallest equipment grounding conductor that can be installed in the conduit?

In determining the minimum size of the equipment grounding conductor (EGC) for a 3-phase load connected to a 600-A circuit breaker with three 350 kcmil conductors, it is essential to refer to the National Electrical Code (NEC) for guidance. The NEC specifies that the size of the EGC must be based on the size of the conductors and the rating of the circuit breaker.

For conductors sized at 350 kcmil, the NEC provides tables that dictate the required EGC size based on the ampacity and type of conductors. According to these tables, for conductors that are 350 kcmil and a circuit rated at 600 amps, the minimum EGC size required is indeed 1 AWG. This requirement ensures proper grounding and helps protect against electrical shock hazards and equipment damage.

Choosing a conductor that is too small can lead to increased resistance, potentially compromising the effectiveness of the grounding system. Conversely, selecting a larger than necessary conductor size is generally permissible but may not be economically practical.

In summary, the minimum EGC for this setup is correctly identified as 1 AWG, ensuring compliance with safety standards and providing adequate grounding for the circuit.