A 400-A service not subject to physical abuse, the GEC to the ground rod must be at least ___ AWG.

A 400-A service not subject to physical abuse, the GEC to the ground rod must be at least ___ AWG.

• A. 6
• B. 2
• C. 3
• D. 1/0

Answer: (A)

The key idea is that the grounding electrode conductor (GEC) size is set by the service rating and the installation conditions, so the bond to the earth is reliable without overheating. For a 400-amp service with the GEC to the ground rod not exposed to physical abuse, the minimum copper size is 6 AWG. This matches the NEC sizing table and provides a durable, conductive path to the earth. If the route could be damaged or if other electrode configurations or materials were used, a larger size would be required per the same table.

The key idea is that the grounding electrode conductor (GEC) size is set by the service rating and the installation conditions, so the bond to the earth is reliable without overheating. For a 400-amp service with the GEC to the ground rod not exposed to physical abuse, the minimum copper size is 6 AWG. This matches the NEC sizing table and provides a durable, conductive path to the earth. If the route could be damaged or if other electrode configurations or materials were used, a larger size would be required per the same table.