Underground metallic structures are now an integral part of any industrial or commercial facility. The length and the number of such objects increases continuously. Are the new line of oil fields, gas pipelines, erection of storage of petroleum products, public utilities, information networks. It is obvious that stable operation of the industry, are used where underground metallic structures depends largely on their reliability. At the stages of design, construction and operation of underground metal structures, the problem arises to protect them from soil corrosion underground. It is known that to reduce the impact of soil (electrochemical) corrosion widely used method of bias potential on the protected construction in a negative region relative to the surrounding soil (soil) by applying external source of energy - the installation of cathodic protection
