This European Standard defines the conditions necessary for an effective application of the cathodic protection method to mitigate corrosive attacks on the external surfaces of above ground storage steel tank bottoms in contact with soil, cushion or foundations. This European Standard specifies the requirements for the design, implementation, commissioning, operation and maintenance of such a cathodic protection system. This European Standard applies both for new and existing tanks. NOTE 1 This European Standard is not applicable to reinforced concrete above ground storage tanks for which EN ISO 12696 applies. NOTE 2 Detailed information concerning measurement techniques of cathodic protection given in EN 13509 are referred to in the present standard. NOTE 3 Cathodic protection of internal surfaces of above ground storage steel tanks storing waters is addressed in EN 12499. NOTE 4 Cathodic protection of external surfaces of buried tanks is addressed in EN 13636.