This paper provides comparison tables between the testrequirements for low-voltage power circuit breakers as specified in UL1066 and the associated ANSI C37 standards, and those for molded casecircuit breakers as specified in UL 489. The major differences in theperformance characteristics of these circuit breakers are discussed withdue reference to the tables. The paper also relates these differences tocircuit breaker applications; with low-voltage power circuit breakerstypically being located upstream from molded case circuit breakers inorder to provide selective coordination. These upstream circuit breakersare typically bussed into the circuit, and can be withdrawn for circuitbreaker maintenance. By contrast molded case circuit breakers are moretypically wired directly into the circuit. Reference is also made toinsulated case circuit breakers (UL 489) and to IEC circuit breakers(IEC 947-2)
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