scope:

This standard covers the following types and preferred ratings for enclosed low-voltage ac power circuit breakers:

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 respectively

b) Unfused or fused type

c) Manually operated or power operated, with or without a trip system

d) Fused drawout assemblies consisting of current-limiting fuses in a drawout 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.

Purpose

This standard

a) Establishes minimal functional requirements

b) Establishes preferred rating structure

c) Provides preferred ratings