An embodiment describes a method for installing a single power cable span in a tunnel having an entrance and an exit. The method includes positioning a head portion of the single power cable span near the entrance and laying the single power cable span in the tunnel past the exit. The laying of the single power cable span comprises repeating a plurality of sub-steps until the head portion reaches an endpoint outside the tunnel. The plurality of sub-steps includes connecting a trolley at the entrance in a slidable manner on a rail longitudinally extending along the tunnel between the entrance and the exit, joining the trolley to a pulling rope and to the single power cable span, and moving the trolley along the rail by pulling the pulling rope by a predetermined length. Another embodiment relates to an equipment for installing a single cable span in a tunnel.