A method and an arrangement for voltage testing and drying an insulated electrical conductor. The insulated conductor is, after the extrusion process, brought through a pipe which is partly closed by a lead-in attached to each end of the pipe. The pipe contains a number of metal spheres which surround the conductor running through the pipe. The movement of the conductor causes the spheres to move around the conductor thus drying the same. An outer voltage source can be connected to a metallic strip inside the pipe and, due to the metal spheres, a test voltage is applied across the insulation of the wire.