A very long underground branch circuit in Schedule 40 PVC runs from a 120/208-volt, 3-phase, 4-wire panel to the load. The branch-circuit conductors are connected to a 30-A circuit breaker. The conductors are 2 AWG. The smallest EGC that can be installed in the PVC is ___ AWG.

A very long underground branch circuit in Schedule 40 PVC runs from a 120/208-volt, 3-phase, 4-wire panel to the load. The branch-circuit conductors are connected to a 30-A circuit breaker. The conductors are 2 AWG. The smallest EGC that can be installed in the PVC is ___ AWG.

• A. 2 AWG
• B. 8 AWG
• C. 3 AWG
• D. 4 AWG

Answer: (A)

Understanding equipment grounding conductor sizing is tested by NEC 250.122. The size of the EGC is determined by the overcurrent protection device protecting the circuit, not by the load conductor size or how long the run is. For a 30-amp branch circuit, the minimum copper EGC required is 10 AWG. Running the conductors through Schedule 40 PVC underground does not change that requirement—the EGC still must provide a low-impedance fault path to let the 30-amp breaker trip. Among the given options, the one that meets this minimum is 8 AWG copper, since 10 AWG is the actual minimum and 8 AWG is the next size up (larger conductor). The other options are either smaller than the minimum or not the smallest size that satisfies the code. The key takeaway is that EGC size is fixed by the protection device rating through 250.122, and length or conduit type doesn’t change that.

Understanding equipment grounding conductor sizing is tested by NEC 250.122. The size of the EGC is determined by the overcurrent protection device protecting the circuit, not by the load conductor size or how long the run is. For a 30-amp branch circuit, the minimum copper EGC required is 10 AWG. Running the conductors through Schedule 40 PVC underground does not change that requirement—the EGC still must provide a low-impedance fault path to let the 30-amp breaker trip.

Among the given options, the one that meets this minimum is 8 AWG copper, since 10 AWG is the actual minimum and 8 AWG is the next size up (larger conductor). The other options are either smaller than the minimum or not the smallest size that satisfies the code. The key takeaway is that EGC size is fixed by the protection device rating through 250.122, and length or conduit type doesn’t change that.