The purpose of this guide is a) to provide a methodology by which the most probable cause of any particular circuit breaker failure may be determined; b) to provide sufficient guidelines and promote uniformity in the analysis of circuit breaker failures; c) to provide guidance for systematic and uniform data collection so that valuable facts are not lost or destroyed; d) to encourage cooperative efforts by users and manufacturers during failure analysis; e) to encourage consistency of nomenclature and compatibility with similar efforts by other organizations such as CIGRE (International Conference on Large Voltage Electric Systems), EEl (Edison Electric Institute), IEC (International Electrotechnical Commission), NEMA (National Electrical Manufacturers Association), and AEIC (Association of Edison Alluminating Companies).