What is the ampacity of a 4/0 AWG THW conductor for use in a branch circuit?

For a 4/0 AWG THW (Thermoplastic Heat and Water-resistant) conductor, the ampacity, or current-carrying capacity, is determined based on the National Electrical Code (NEC) and the specific conditions under which the conductor will be installed.

In general, 4/0 AWG copper conductors have an ampacity that can vary based on the insulation type and installation conditions. For THW conductors in a typical branch circuit, the ampacity is generally rated at 225 A. This rating takes into account factors such as ambient temperature and the number of conductors bundled together, which could require derating of the capacity.

It's important to note that the ampacity ratings are provided in NEC tables, and for THW conductors, the standard rating for a 4/0 AWG would be listed around that 225 A mark for typical installations. This understanding is crucial when determining the suitability of conductors for specific applications to ensure they can safely handle the electrical load without overheating.

The other options represent ampacities that either exceed the typical rating for a 4/0 AWG THW conductor or do not align with the commonly accepted values according to electrical codes.