Specifications and standards for circuit breakers and supplementary protectors

June 1, 2007
This paper provides a clear understanding of UL standards and requirements design engineers can use to assure optimal performance and safety.

From E-T-A Circuit Breakers

Electrical engineers do not want to see designs go up in smoke. However, there is widespread misunderstanding of industry standards for circuit protection and the meaning of terms such as "circuit breakers," "supplementary protectors," "circuit breakers for equipment" and "branch circuit protection." In some cases, this confusion results in the specification of the wrong type of circuit protection and increases the risk of overheating, premature failure and catastrophic faults.

As electrical and electronic equipment increases in complexity, it is necessary to protect the operator from the effects of equipment failure and protect the equipment from costly damage and downtime. To understand the source of the confusion and to learn how to specify circuit protection correctly, this paper provides readers with a review of standards and how they are applied.