Cable reel assembly for holding a wound quantity of tool cable, wherein said tool cable comprises at a first end a means to connect to a portable electrical tool, and at the other end a means to connect to an electronic control system for said tool, and wherein said cable reel assembly comprises an electronic control system to drive and control the rotation of the reel assembly for retracting or paying out the tool cable, said cable reel assembly comprising: a. a supporting frame having a fixed hub holding an elongated shaft projecting from said hub and said supporting frame, said shaft having a central axial aperture extending therethrough; b. a slip ring capsule for signal transfer, said slip ring capsule being provided within the central axial aperture in said shaft and along the central axis of said shaft, said slip ring capsule comprising: i. a set of contact brushes; ii. a set of contact slip rings for electrical contact with the set of contact brushes, and rotatably mounted relative to the set of contact brushes; c. a rotatable reel comprising a hub, whereby said hub is mounted rotatably around the shaft, which reel further comprises a hollow drum attached to said hub of the reel, preferably said hollow drum comprising two flanges (4, 26) projecting radially therefrom, with said flanges having sufficient height to accommodate a cable therebetween wound on said drum; d. an electric motor for alternately rotating said reel around said shaft in a first direction to pay out a cable attached to said reel assembly, and for rotating said reel around said shaft in a second opposite direction to retrieve paid out cable for containment on said reel assembly; e. an electronic control system to drive and control the rotation of the reel; characterized in that the shaft comprises at least one, preferably circular, contact ring on its outer surface, and whereby said reel further comprises a contact brush holder comprising at least one contact brush for continuous electrical contact and transferring electric power, for the portable electronic tool, with the at least one contact ring on the shaft, which contact brush holder is attached to the hollow drum extending along the axis of rotation of the hub of the reel, whereby the portion of the shaft comprising said contact ring is provided within the hollow drum, and whereby the contact brush holder is provided within the hollow drum, whereby said hollow drum has a closed barrel being entirely closed at the furthest end of the barrel facing away from the supporting frame and whereby the closest end of the barrel facing towards the supporting frame is attached to the hub of the reel thereby forming a closed surface around the shaft, and whereby the hub of the reel is rotatably mounted on the shaft by bearing materials. a. a supporting frame having a fixed hub holding an elongated shaft projecting from said hub and said supporting frame, said shaft having a central axial aperture extending therethrough; b. a slip ring capsule for signal transfer, said slip ring capsule being provided within the central axial aperture in said shaft and along the central axis of said shaft, said slip ring capsule comprising: i. a set of contact brushes; ii. a set of contact slip rings for electrical contact with the set of contact brushes, and rotatably mounted relative to the set of contact brushes; i. a set of contact brushes; ii. a set of contact slip rings for electrical contact with the set of contact brushes, and rotatably mounted relative to the set of contact brushes; c. a rotatable reel comprising a hub, whereby said hub is mounted rotatably around the shaft, which reel further comprises a hollow drum attached to said hub of the reel, preferably said hollow drum comprising two flanges (4, 26) projecting radially therefrom, with said flanges having sufficient height to accommodate a cable therebetween wound on said drum; d. an electric motor for alternately rotating said reel around said shaft in a first direction to pay out a cable attached to said reel assembly, and for rotating said reel around said shaft in a second opposite direction to retrieve paid out cable for containment on said reel assembly; e. an electronic control system to drive and control the rotation of the reel;