The purpose of this standard practice is to provide a method for evaluating the effectiveness of a CP system using coupons. Coupons are used to determine the level of corrosion protection provided by a cathodic protection (CP) system to a variety of structures, such as buried or submerged pipelines, underground storage tanks (USTs), aboveground (on-grade) storage tank bottoms, and steel in reinforced concrete structures. IR drop produces an error in the structure-to-electrolyte potential measurement, and this IR drop can be a function of reference electrode placement, soil resistivity, burial depth of the structure, coating condition, stray currents, local or long-line corrosion cells, and the amount of CP current applied. This standard is maintained by Task Group 210.