Revision Standard - Superseded. Metal-enclosed (ME) bus assemblies for indoor and outdoor use are covered in this standard. The types of assemblies covered are nonsegregated-phase bus, segregated-phase bus, and isolated-phase bus. Rated maximum voltages of ac ME bus assemblies range from 0.635 kV through 38 kV with continuous current ratings of 600 A through 26 000 A for self-cooled ratings and up to 40 000 A and above for force-cooled ratings. Rated maximum voltage levels of dc bus assemblies range from 300 V through 3200 V with continuous current ratings of 600 A through 12 000 A. Service conditions, ratings, temperature limitations and classification of insulating materials, insulation (dielectric) withstand voltage requirements, test procedures, and application are discussed. A guide for calculating losses in isolated-phase bus is included.