An end-block for electrically energising a rotatable tubular target in a vacuum coating installation is disclosed. The end-block has a rotary electrical contact that reduces the joule heating effects when operating in alternating current mode. When compared to known end-blocks, this is achieved by increasing the number of contact areas between a contacting ring and a series of circumferentially mounted contacting shoes. Also the contact shoes are being pressed radially outwardly by means of resilient elements against the contacting ring.