This standard covers the following types and preferred ratings for enclosed low-voltage ac power circuit breakers: a) Stationary-mounted or drawout-mounted type of two-, three-, or four-pole construction with one or more rated maximum voltages of 1058 V, 730 V, 635 V (600 V for units incorporating fuses), 508 V, or 254 V for application on systems having nominal voltages of 1000 V, 690 V, 600 V, 480 V, or 240 V respectively b) Unfused or fused type c) Manually operated or power operated, with or without a trip system d) Fused drawout-mounted assemblies consisting of current-limiting fuses in a drawout-mounted assembly intended to be connected in series with a low-voltage ac power circuit breaker to form a nonintegrally fused circuit breaker In this standard, the term circuit breaker shall mean enclosed low-voltage ac power circuit breaker, either fused or unfused. The term unfused circuit breaker shall mean a circuit breaker without either integrally or nonintegrally mounted fuses, and the term fused circuit breaker shall mean a circuit breaker incorporating current-limiting fuses, whether integrally mounted or nonintegrally mounted. This standard: a) Establishes minimal functional requirements. b) Establishes preferred rating structure. c) Provides preferred ratings. Revision Standard - Active. The following enclosed low-voltage ac power circuit breakers are covered in this standard: a) stationary or drawout type of two-, three-, or four-pole construction, with one or more rated maximum voltages of 1058 V, 730 V, 635 V (600 V for units incorporating fuses), 508 V, or 254 V for application on systems having nominal voltages of 1000 V, 690 V, 600 V, 480 V, or 240 V; b) unfused or fused circuit breakers; c) manually or power operated; and d) with or without electromechanical or electronic trip devices. Service conditions, ratings, functional components, temperature limitations and classifications of insulating materials, insulation (dielectric) withstand voltage requirements, test procedures, application, and the preferred ratings are discussed in this standard.