Interior metal water piping located more than ___ ft from the point of entrance to the building shall not be used as a part of the grounding electrode system.

• A. 3
• B. 5
• C. 8
• D. 10

Answer: (B)

The rule focuses on where interior metal water piping can be used as part of the grounding electrode system. Water piping can serve as a grounding path only if it is within a short distance of where the service enters the building, so the bond to the service equipment is reliable. If the piping is located more than five feet from the point of entrance, that bond becomes unreliable due to potential breaks, joints, or nonconductive sections, so it cannot be used as a grounding electrode. So the allowable distance is within five feet, making five feet the cutoff.