What is the required grounding method for metal water piping?

The correct grounding method for metal water piping is that it must be bonded and connected to the grounding system. This is crucial for safety reasons.

Metal water pipes can act as a conductor for electrical currents if there's a fault in the electrical system. Bonding the metal piping provides a path for fault current to ground, minimizing the risk of electrical shock or fire. It ensures that all metal components of the plumbing system are at the same electrical potential, reducing the chance of stray voltage.

In many electrical codes, including the National Electrical Code (NEC), there are specific requirements outlining how water pipes must be bonded to the building's grounding system. This includes connecting the pipes to the grounding system at specific points to ensure effective grounding.

Other grounding methods or lack thereof, such as leaving it unbonded, not requiring grounding, or grounding only in wet areas, do not comply with established safety standards and could lead to dangerous situations, such as electrical shocks or equipment damage. Therefore, proper bonding and connection to the grounding system is a necessary safety measure.