National Electrical Code (NEC) Article 230 Practice Exam

In a typical residential installation, the size of the conductor for the service entrance largely depends on the overall load and the material used for the conductors. According to NEC guidelines, for a standard residential service entrance using copper conductors, a size of 8 AWG is appropriate for a 40-amp residential service. This size is often used for feeders and branch circuits, providing a balance between conductivity and safety.

The choice of copper conductors over aluminum is important because copper has a higher conductivity, allowing it to carry a heavier load efficiently. While aluminum conductors can be used, they generally require a larger size to carry the same current due to their lower conductivity, often making them less efficient for typical residential service installations.

Understanding these distinctions helps ensure that electrical installations comply with safety codes and can efficiently handle the electrical demands of a residential setting.