Rule 4.12.718 - ELECTRICAL EQUIPMENT AND WIRING(1) Electrical equipment and wiring for use in anhydrous ammonia installations shall be either general purpose or weather resistant as appropriate.(2) Where concentrations of ammonia in air in excess of 16 percent by volume are likely to be encountered, electrical equipment and wiring shall be of a type specified by and installed in accordance with National Electrical Code (National Fire Prevention Association 70, ANSI-C1) for Class 1, Group D locations.NEW, 1986 MAR p. 1820, Eff. 10/31/86.Sec. 80-10-503, MCA; IMP,. 80-10-503, MCA;