UL Standards & Engagement Circuit Breakers for Use in Communications Equipment UL 489A

1.1 The requirements of this standard cover single pole or multi-pole DC rated circuit breakers intended for use as branch circuit overcurrent and short-circuit protection in communications equipment. 1.2 All poles of multi-pole circuit breakers covered by this standard operate at the same potential. 1.3 The requirements of this standard cover devices rated 600 volts DC or less. 1.4 This standard is intended to be used with the Standard for Molded-Case Circuit Breakers, Molded-Case Switches and Circuit-Breaker Enclosures, UL 489, as the requirements of this standard modify tests described in that standard. 1.5 Unless otherwise specified, when the term "circuit breaker" is used in this standard, it refers to a circuit breaker intended for use with communications equipment.