What would be the minimum service entrance cable size for a 200-amp supply?

For a 200-amp service entrance, the minimum cable size required is crucial for safe and efficient electrical distribution. The National Electrical Code (NEC) provides guidelines for determining the appropriate sizes based on the material of the conductors—either copper or aluminum.

In this case, for copper conductors, a size of 2/0 (two-ought) is specified as the minimum required to safely carry a 200-amp load. Copper has better conductivity compared to aluminum, which means it can carry more current for a given size.

For aluminum conductors, the minimum size increases because aluminum is less conductive than copper. Therefore, a 4/0 (four-ought) aluminum conductor is necessary to handle the same amount of current as the smaller 2/0 copper conductor. This means that the correct answer correctly identifies that for a 200-amp service, the service entrance cable must be either 2/0 copper or 4/0 aluminum to meet the safety requirements outlined in the NEC.

This ensures that the electrical system operates effectively while minimizing the risk of overheating and potential failure.