Abstract: Protective regulations are specified both in China and abroad concerning the stray current interference on long distance pipeline from heavy power lines and power supply distribution and substation grounding syste'ms. Although available are -the somewhat well developed practices against interference of heavy power on the equipment and facilities in tank farm, corresponding protective standards, especially a system of protective indices, are not yet specified by authorities concerned. Based on different classes of explosion hazard for the equipment and facilities in tank farm, with the experience of protecting a tank farm from interference of electrical railroad, relavent protective indices for tank farm protection are given on the basis of related foreign standards and data concerning explosion protection, industrial power, long distance pipeline, and tank farm construction. The indices are discussed by classifying them into three categories: voltage(potential)/current, safety clearance, and electrical resistance.