A connecting device for a fiber optic cable includes a first part having first and second electrical connectors located on its housing, and a second part having a third electrical connector located on its housing. The second and third electrical connectors are adapted to be mechanically and electrically connect with each other or disconnected from each other. The first part has electrical components disposed within its housing and electrically connected to the first and second electrical connectors. The second part receives end portions of optical fibers of the fiber optic cable; it has optical transceivers within its housing but no other electrical circuitry. Also disclosed is a cable device employing an optical fiber cable and two connecting devices at its two ends, at least one of which having a structure described above. Various form factors can be adopted for the first part, including a plug, wall plate, standalone box, etc.