This SAE Standard defines the test conditions, procedures, and performance requirements for circuitbreakers in ratings from 50 to 200 A. This document covers automatic reset, modified reset and manualreset types of circuit breakers for low voltage DC systems (12 V and 24 V).NOTE— It is technically feasible for circuit breakers in this general class to be provided in amperage ratings below 50 A. In those instances, the procedures as detailed herein may be used providedcompensation is made for test currents, test leads, and power supply requirements. Additionalguidance may be obtained from SAE J553 – Circuit Breakers.1.1 Operational requirements for 42V vehicular electrical systems are under development as of thisrevision. The electrical environment is not completely defined, particularly as it relates to other components that would influence circuit breaker function (such as storage battery technology, charging system design and operational characteristics). The test and evaluation requirements of this standard are sufficient to determine relative performance concerning current carrying capability, environmental durability, and general requirements regardless of maximum voltagerating. It is anticipated that a separate technical document will be created to capture requirementsunique to 42V electrical system architecture and load characteristics.