This standard covers assemblies of metal-enclosed (ME) conductors along with associated interconnections, enclosures, and supporting structures. When switches and disconnecting links are included, they shall conform to this standard. This standard is concerned with performance characteristics of enclosed, rather than open, indoor and outdoor conductor assemblies with rated maximum operating voltages through 38 kV. While this standard does cover 600 V bus assemblies, it does not pertain to UL 857-2001 type busways and associated fittings, nor does it pertain to ME bus assemblies utilizing cables as the primary conductors. The Standard for Metal-Enclosed Bus was last updated in 1987. The standard needs to be updated to harmonize with certain other standards within the C37.2XXX series of documents. Revision Standard - Superseded.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.