A basic corrosion cell is formed when two dissimilar metals (an anode and a cathode) are placed in a common electrolyte and connected by a conductive material. In the case of the tower "dead man" guy anchor, the dissimilar metals are the steel anchor shaft (anode) and the typical copper grounding system (cathode). The steel exposed to soil also "sees" the steel in concrete as if it were copper, creating a second large cathode. The soil and concrete are electrolytes. A conductive path is formed through the grounding-to-guy cable connections. "Battery action" begins and electrical potential can be measured. The electrical flow causes the anode to deteriorate, sometimes catastrophically. This deterioration is what we call "rusting" or corrosion.