Low-voltage metal-enclosed switchgear, which can contain either stationary or drawout, manually or electrically operated low-voltage AC or DC power circuit breakers in individual grounded metal compartments, in three-pole, two-pole, or single-pole construction is covered. Rated maximum voltage levels can be 254 V, 508 V, or 635 Vac and 300/325 V, 800 V, 1000 V, 1600 V, or 3200 Vdc. The continuous current ratings of the main bus in ac designs can be 1600 Al 2000 A, 2500 A, 4000 A, 6000 A, 8000 A, 10,000 A, or 12,000 A. The switchgear can also contain associated control, instruments, metering, protective, and regulating devices as necessary. The standard deals with service conditions, ratings, temperature limitations, and classification of insulating materials, insulation (dielectric) withstand voltage requirements, test procedures, and application.