Stray current interference sources includes Cathodic protection systems, AC or DC powered rail systems, HVDC or AC power lines, and Telluric or geomagnetic currents
Stray Current Interference
Stray currents are currents through electrical paths from external sources which deviate from its intended circuit. Any metallic structure such as a buried pipeline in soil represents a low resistant current path and is thus vulnerable to the effect of stray currents causing either current pick up or discharge or both. This will cause either over protection or under protection or sections undergoing over protection and under protection at different locations.

Harmful effects of Stray Current Interference
Stray current interference is very damaging for steel pipelines and other structures because it involves huge current and a small coating defect or holiday may cause extensive corrosion and metal loss of structure. The corrosion is localized and mostly pitting corrosion and a deep pit is formed due to localized current discharge. The rail transit system or underground mining railroad system pipeline may discharge a large stray current and cause severe corrosion in a small area of holiday. According to Faradays law, Ferrous metals have metal loss of 9.1 Kg/A-year so a large discharging current will destroy the metal in a very short time may be in hours or days depending upon cycle of discharge.

URL: https://marcepinc.com/blog/examples-of-stray-current-interference

Author's Bio: 

Marcep Inc. is a division of Marcep Group which has a JV with some of the major projects over the world and has entered the Asian market in sharing knowledge to the industry.