What is the minimum size AWG copper conductor permitted for a calculated branch-circuit load of 173 amperes?

To determine the minimum size of an AWG copper conductor suitable for a calculated branch-circuit load of 173 amperes, it is important to refer to the National Electrical Code (NEC) tables, which provide guidance on conductor sizing based on ampacity.

For copper conductors, the ampacity is dictated by the conditions of use, including the ambient temperature, insulation type, and installation conditions. According to NEC Table 310.16, for copper conductors:

• A 1 AWG copper conductor has an ampacity of 130 amperes (in a typical installation scenario).

• A 2/0 AWG copper conductor has an ampacity of 175 amperes.

• A 4 AWG copper conductor has an ampacity of 95 amperes.

• A 3/0 AWG copper conductor has an ampacity of 200 amperes.

Given that the load is 173 amperes, the conductor must be able to carry at least this amount safely. Thus, the 2/0 AWG conductor is the correct choice because it meets the requirement at 175 amperes, providing a margin over the load and ensuring safety. Meanwhile, the other conductors do not meet the load requirement, making them unsuitable