When using metal underground water piping as the only grounding electrode, what additional requirement must be met?

Using metal underground water piping as the only grounding electrode requires it to be supplemented by an additional grounding electrode. This is due to the fact that while metal water piping can function effectively as a grounding electrode, it may not provide a sufficient path to ground under all conditions. Factors such as corrosion, the presence of non-metal fittings, or the potential for interruption in continuity can compromise its effectiveness.

Supplementing it with an additional grounding electrode increases reliability and safety by ensuring that there is an alternative path to ground, which is essential in the event of a fault or surge. This practice aligns with electrical code requirements, which aim to enhance safety and reduce the risk of electrical shock or equipment damage. By having multiple grounding electrodes, the overall grounding system’s performance is improved and ensures compliance with necessary regulations.