The purpose of this document is to describe product classes and properties, representing the MCB (Miniature Circuit-Breaker), to become a part of the IEC 63508 DB. It includes data needed for product selection as well as data needed for engineering. This IEC 63508 DB intends, as a contribution to the IEC Common Data Dictionary, to be used by catalogue consortia, other database standards and software as a data reference for circuit-breakers and similar equipment for household use. NOTE In the future, it is intended to extend the IEC 63508 DB to other type of products managed by IEC SC 23E.