What is the smallest gauge conductors permitted by the NEC® for a 200-A residential service?

The National Electrical Code (NEC) stipulates specific requirements for conductor sizes based on the ampacity, or maximum current-carrying capacity, needed for electrical services. For a 200-amp residential service, the NEC requires the use of a minimum of 2/0 AWG copper conductors or a minimum of 4 AWG aluminum conductors.

Choosing 2/0 AWG for copper wire ensures that the conductors can safely carry the load without overheating or posing safety risks due to inadequate sizing. This gauge provides sufficient capacity for a standard residential service of this amperage. It is crucial to adhere to these requirements to maintain electrical safety and compliance with the NEC.

The other options, while they may have different ratings for different applications, do not meet the minimum requirements for a 200 A service when considering typical residential settings. Therefore, using 2/0 AWG is the correct choice for ensuring proper and safe operation in a 200-amp residential service application.