Two Cases of Corrosion in Suburban New York Disguised as Galvanic —Their Cause and Mitigation

Abstract

Abstract Two cases are reported in which stray current potentials were mistaken for galvanic potentials from underground lead-sheathed telephone cables to ground. Lack of suitable meters prevented assessment of the true potentials of the cables which suffered severe corrosion damage. Case 1 pertains to a relatively high stray current area adjacent to both the New York City subway system and the electrified New York Central Railroad. First tests showed steady positive potentials similar to those which might result from a galvanic source. When the fixed potential was blocked out by an opposite fixed potential, a marked fluctuation of potentials to earth was observed. Bonding reduced the cable-to-earth potential to a range of —0.1 to —0.4 volt. Case 2 pertains to a section of cable where an average of 8.9 failures per 100 sheath miles per year occurred over an extended period of time. The damage began to occur shortly after discontinuance of a trolley system. A rectifier-powered cathodic protection system, i...