North Carolina Home Inspector Practice Exam

What size ground wire must be used in a 200-amp service?

1. No. 4

2. No. 6

3. No. 8

4. No. 10

The correct answer is: No. 6

In a 200-amp service, the appropriate size for the ground wire, according to the National Electrical Code (NEC), is typically No. 6 copper or No. 4 aluminum. The establishment of this size is based on the ampacity requirements necessary to ensure that the ground wire can safely carry the fault current without risk of overheating or damage. Copper wire has better conductivity compared to aluminum, so it can be sized smaller for the same application. Thus, a No. 6 copper ground wire is a commonly accepted choice for a 200-amp service, as it can adequately handle the electrical load while providing the necessary safety and protection. The correct size for the ground is critical for preventing electrical hazards, such as shock or fire, which could occur if the ground wire is insufficient for the system's load. Other options, although they may be mentioned in various contexts, do not meet the NEC guidelines for this specific application. Selecting the appropriate ground wire size is particularly important for grounding systems in residential electrical installations.