An electrode slipping device for a graphite electrode comprising an upper holder ring and a lower holder ring, the upper holder ring and the lower holder ring containing one or more clamping assemblies including a clamping shoe and a clamping device arranged in co-operation with each other so that the clamping shoe is operable between a clamping position, where an electrode is clamped, and a release position, where the electrode is unclamped, and wherein the clamping device comprises - a frame element fixedly attachable to a holder ring (2, 3) to be stationary in relation to the holder ring, - a cylinder portion, the cylinder portion being arranged stationary in relation to the frame element, - a plunger, the plunger comprising a cylindrical housing and an end plate arranged to be engaged with the clamping shoe, - a pressing spring arranged inside the cylindrical housing to act between the frame element and the plunger, for urging the plunger towards the clamping shoe and for pressing the clamping shoe against the electrode, - a tension bar having a first end releasably attached to the end plate of the plunger, and a second end, - a piston element arranged movable inside the cylinder portion to form a hydraulic power means wherein the piston element can be moved by hydraulic pressure of hydraulic fluid which is arranged to be guided to a space between the piston element and the cylinder portion, whereby movement of the piston element by hydraulic pressure of the hydraulic fluid causes the tension bar to pull the plunger against the spring force of the pressing spring to move the clamping shoe from the clamping position to the release position, and a contact shoe made of electrically conductive material for supplying current to the electrode, characterised in that the clamping device comprises one and single tension bar arranged centrally in relation to the frame element, the plunger, the pressing spring and the piston element, and wherein the lower holder ring comprises a single clamping device arranged to releasably press one clamping shoe against the surface of the electrode, and the contact shoe being arranged at an opposite side of the lower holder ring in relation to the position of the clamping shoe. - a frame element fixedly attachable to a holder ring (2, 3) to be stationary in relation to the holder ring, - a cylinder portion, the cylinder portion being arranged stationary in relation to the frame element, - a plunger, the plunger comprising a cylindrical housing and an end plate arranged to be engaged with the clamping shoe, - a pressing spring arranged inside the cylindrical housing to act between the frame element and the plunger, for urging the plunger towards the clamping shoe and for pressing the clamping shoe against the electrode, - a tension bar having a first end releasably attached to the end plate of the plunger, and a second end, - a piston element arranged movable inside the cylinder portion to form a hydraulic power means wherein the piston element can be moved by hydraulic pressure of hydraulic fluid which is arranged to be guided to a space between the piston element and the cylinder portion, whereby movement of the piston element by hydraulic pressure of the hydraulic fluid causes the tension bar to pull the plunger against the spring force of the pressing spring to move the clamping shoe from the clamping position to the release position, and a contact shoe made of electrically conductive material for supplying current to the electrode,