Apparatus consuming heavy electric current, such as an arc furnace, has concentric members (1) and (3) between which the current has to be transferred. The member (3) can rotate around, and/or move axially with respect to, member (1). Interposed, an annular member (2) has helically twisted tufts (11) of copper wire slidably retained by bushes (12) in a hole (10). The copper wires are compressed to fit between the members (1) and (3), and the compression is stored as elastic helical twisting energy, ensuring good contact pressure to transfer current between the members (1) and (3).