What is the minimum size for underground service conductors supplying power to limited loads of a single branch circuit?

The minimum size for underground service conductors for limited loads of a single branch circuit can be determined based on the National Electrical Code (NEC). According to NEC guidelines, conductors must be appropriately sized to handle the expected load and provide safety and reliability.

The key point is that for limited loads, different types of conductors can be used, each with its minimum size requirements. Both 10 AWG aluminum and 10 AWG copper conductors are suitable for such applications, as they can handle the necessary ampacity while ensuring safety against overheating. Additionally, a 12 AWG copper conductor is also adequate for limited load applications. This indicates that in light of the NEC provisions, all the specified conductor types and sizes are permissible under the right conditions.

Thus, since all the given choices (10 AWG aluminum, 10 AWG copper, and 12 AWG copper) meet the code requirements for serving limited loads, the aggregate choice of all options accurately reflects the options allowed for underground service conductors in this scenario.