What is the maximum distance that interior metal water pipes must be located from the building entrance to be part of the grounding electrode system?

The maximum distance that interior metal water pipes must be located from the building entrance to be part of the grounding electrode system is 3 feet. This requirement ensures that the grounding system is effective in providing a low-resistance path for electrical faults to safely dissipate into the ground.

When the water piping is close to the service entrance, specifically within this 3-foot perimeter, it can effectively connect with the grounding system and provide a reliable grounding electrode. This distance is significant because it maintains a minimal impedance path for fault currents, which is essential for the safety and functionality of electrical systems within a building.

Understanding this requirement is critical for electrical inspectors, as it helps ensure that the grounding electrode system complies with safety codes and standards, thus reducing the risk of electrical shock or fire hazards. Adhering to this 3-foot distance also aligns with the guidelines stipulated in the National Electrical Code (NEC), which emphasizes the importance of properly located grounding electrodes to protect both people and equipment from possible electrical failures.