Cathodic Protection — Stray Current Corrosion

Protection technique against electrochemical corrosion of buried metallic infrastructure (cable sheaths, earth electrodes, pipelines), caused by stray currents flowing through the soil from nearby DC systems such as tram rails, charging infrastructure or other cathodically protected structures. Cathodic protection turns the object to be protected into a cathode by directing a DC current toward it, either via sacrificial anodes (galvanic, e.g. zinc or magnesium) or via an impressed-current system with an external rectifier and inert anodes. When new installations share a trench with other buried assets, the interaction between cathodically protected and unprotected objects must be assessed, because an unprotected object next to a protected one can actually corrode faster at the point where the protective current leaves it again.