This standard covers assemblies of metal-enclosed (ME) conductors along with associated interconnections, enclosures, and supporting structures. The types of assemblies covered are nonsegregated-phase bus, segregated-phase bus, isolated-phase bus, and cable bus. When switches and disconnecting links are included, they shall conform to this standard. This standard encompasses the performance characteristics of indoor and outdoor conductor assemblies with rated maximum operating voltages through 38 kV. This standard does not pertain to UL 857 [B22] type busways and associated fittings. Service conditions, ratings, temperature limitations, and classification of insulating materials, insulation (dielectric) withstand voltage requirements, test procedures, and applications are established. A guide for calculating losses in isolated-phase bus is included.