A connection device for connecting an optical fiber to an electrical device has a housing, a cable gland, and a plug for insertion into the corresponding socket of the electrical device, the housing having a cable passage for insertion of the optical fiber, the plug being held at least partially in the housing and being connectable to the fibers of the optical fiber which has been inserted into the cable passage. The housing has a first housing part for holding the plug and a second housing part for connection to the cable gland. The first and second housing parts are connectable in a manner enabling them to be axially moved relative to each other in the connected state by an extent defined by at least one stop on the second housing part that is engageable with at least one opposing stop on the first housing part.