Solution for installing an in-house or in-building optical data network

The invention provides a cover plate (10) of a socket outlet for providing electrical power to an electrical appliance. The cover plate comprises one or more holes (11,12) for receiving one or more POF cables (30). The hole has a diameter matching the diameter of the POF cable such that the POF cable is frictionally fixable in the hole when inserted into the hole. Furthermore an optical device is provided that is insertable into the socket outlet. The optical device can receive power from the socket outlet. The optical device comprises one or more holes aligned with the holes in the cover plate for making an optical data connection with the POF cables.