Grounding and Corrosion of Dissimilar Materials
Grounding connections have applications both above and below grade and as such, are subject to various kinds of corrosion.
Above grade corrosion takes place mainly through galvanic action when two metals are exposed to an electrolyte. This type of corrosion is most pronounced when the connector material differs significantly from the conductor material in nobility. In the presence of an electrolyte solution, a galvanic cell forms allowing direct current (ions) to flow from the more positive anodic to the more negatively charged cathodic material. Over time, the loss of material at the connection interface whether it is from the connector or conductor will cause an increase in electrical resistance resulting in a reduction in overall performance and possibly eventual failure. Like-metals in direct contact are less subject to galvanic corrosion because they are close in electrical potential.
This paper focused on study of Copper to Steel connection and Copper to Galvanized steel as most used material for grounding applications; and above the grade applications.