The methods and systems of lower the grounding potential of an AC electrical grid for protecting a potable water delivery systems from corrosion due to a chemical redox reaction between protective concentration of disinfection chemicals in water and iron, lead and/or copper metal pipes within the potable water delivery system. The methods protect the surface of interactive metals more noble than zinc. These methods are also effective in corrosion protection of the national metallic infrastructure of metals more noble than zinc, such as street signs, lights stands, bridges, and any systems connected to the electrical grid.