This standard describes the general principles which allow the implementation of a system of cathodic protection against corrosive attacks on buried or immersed metal structures. This standard indicates parameters that should be met to achieve cathodic protection as well as rules and procedures that should be followed for design, installation commissioning and maintenance of the protective system. The phenomena of electrochemical corrosion which may occur on a metal structure when in contact with an electrolyte may become worse due to currents from external electric sources.