Revision Standard - Active."Low-voltage metal-enclosed switchgear--which contains either stationary or drawout,manually or electrically operated low-voltage ac or dc power circuit breakers in individual groundedmetal compartments, in three-pole, two-pole, or single-pole construction--is covered. Ratedmaximum voltage levels are 254 V, 508 V, or 635 V (ac) and 300/325 V, 800 V, 1000 V, 1200 V,1600 V, or 3200 V (dc). The preferred continuous current ratings of the main bus in ac designs are1600 A, 2000 A, 3000 A, 3200 A, 4000 A, or 5000 A. For dc designs, the preferred ratings are1600 A, 2000 A, 2500 A, 3000 A, 4000 A, 5000 A, 6000 A, 8000 A, 10000 A, or 12000 A. Theswitchgear may also contain associated control, instruments, metering, protective, and regulatingdevices as necessary. The standard deals with service conditions, ratings, temperature limitations,and classification of insulating materials, insulation (dielectric) withstand voltage requirements, testprocedures, and application."