Conductor rail system for connecting an electrical device, especially a luminaire, whereby the conductor rail system comprises: • at least one longitudinal mounting rail with a longitudinal axis, with two side walls and a bottom wall, whereby preferably the mounting rail has a U-shape in a cross-section perpendicular to the longitudinal axis; • an electroconductor profile held by said mounting rail, whereby the electroconductor profile comprises wires for an electric power supply and/or for transmission of control and/or data signals, and whereby the electroconductor profile is preferably arranged on the inside of the mounting rail; • a gear tray, whereby the gear tray is moveable along the longitudinal direction of the electroconductor profile and thus the mounting rail; • a connecting element connecting the gear tray and the electrical device; • an elongated and flexible cover, which is held between the two side walls of the mounting rail, whereby the cover is mounted movably along the longitudinal direction of the mounting rail, and whereby the cover is connected with the connecting element and is further configured to move along with a movement of the electrical device, and whereby the cover covers at least a determined part of the mounting rail in any position of the gear tray and thus of the electrical device, characterized in that, the cover has end pieces at its ends, whereby these end pieces are connected by an end piece connection element (115, 116), such that the cover, the end pieces and the end piece connection element (115, 116) form a loop, whereby the mounting rail comprises a guide element in each of its two end face areas, whereby the guide element supports the movement of the cover, and whereby the cover is at least partially bent around the guide element. • at least one longitudinal mounting rail with a longitudinal axis, with two side walls and a bottom wall, whereby preferably the mounting rail has a U-shape in a cross-section perpendicular to the longitudinal axis; • an electroconductor profile held by said mounting rail, whereby the electroconductor profile comprises wires for an electric power supply and/or for transmission of control and/or data signals, and whereby the electroconductor profile is preferably arranged on the inside of the mounting rail; whereby the electroconductor profile comprises wires for an electric power supply and/or for transmission of control and/or data signals, and whereby the electroconductor profile is preferably arranged on the inside of the mounting rail; • a gear tray, whereby the gear tray is moveable along the longitudinal direction of the electroconductor profile and thus the mounting rail; • a connecting element connecting the gear tray and the electrical device; • an elongated and flexible cover, which is held between the two side walls of the mounting rail, whereby the cover is mounted movably along the longitudinal direction of the mounting rail, and whereby the cover is connected with the connecting element and is further configured to move along with a movement of the electrical device, and whereby the cover covers at least a determined part of the mounting rail in any position of the gear tray and thus of the electrical device, whereby the cover is mounted movably along the longitudinal direction of the mounting rail, and whereby the cover is connected with the connecting element and is further configured to move along with a movement of the electrical device, and whereby the cover covers at least a determined part of the mounting rail in any position of the gear tray and thus of the electrical device, the cover has end pieces at its ends, whereby these end pieces are connected by an end piece connection element (115, 116), such that the cover, the end pieces and the end piece connection element (115, 116) form a loop, whereby the mounting rail comprises a guide element in each of its two end face areas, whereby the guide element supports the movement of the cover, and whereby the cover is at least partially bent around the guide element.