This standard provides a recommended procedure for the selection@ application@ and determination of the remaining life in molded case circuit breakers. This recommended procedure is safe and easily understood. Purpose Molded case circuit breakers are one of the most widely used circuit protection devices in low-voltage (less than 1000 volt) applications. In spite of their wide use in industry@ the average person specifying@ installing@ operating and maintaining these devices has less than a complete understanding of them. The purpose of this document is to provide people who purchase or maintain molded case circuit breakers with a single document that includes the following information: ?? How molded case circuit breakers operate ?? How to correctly size and select molded case circuit breakers ?? How to safely maintain molded case circuit breakers ?? How to determine when a molded case circuit breaker must be replaced