This technical report presents an analysis of the risk of influencing factors for brittle fracture of composite insulators that are mostly loaded in the tensile mode (suspension and tension insulators). Guidance is given to reduce the risk of in-service brittle fractures.This phenomenon is limited to tension and suspension insulators. However, the generalinformation given concerning the importance of various parameters can be used as aguideline for the design and production of any kind of composite insulator.