An electrical socket that includes at least two electrical terminals each operatively engagable by a respective prong of an electrical plug by insertion into a respective opening of a housing of the electrical socket. A cover plate is provided to, in one position cover the openings of the housing and in another position expose the openings of the housing through corresponding apertures through the cover plate. The cover plate is mounted for slidable linear movement between the one position and another position relative the housing. There is a surface or surfaces presented by the cover plate non-parallel (and preferably lateral) to the direction of movement to abut a stop surface(s) of the housing that prevent advancement of the cover plate towards the another position when only one aperture is engaged by an object to move the cover plate by virtue of a non linear movement of the cover plate relative to said housing.