A connecting element for connecting a fiber-optic light guide to a light source one time and detaching the fiber-optic light guide from a light source one time is provided. The connecting element includes a housing having a wall, where the housing encloses a cavity, a fiber-optic light guide that passes through the housing and the cavity, a connecting piece corresponding to a connecting section of the light source for establishing the connection to the light source, where the connecting section can be reused after the detachment, and prevention device configured to prevent repeated use of the connecting element and/or the light guide.