An insulated conductor for high-voltage windings in electric machines employs conductor formed of one or more strands, an inner, first semi-conductive layer surrounding the strands, a first insulating layer surrounding the inner, first semi-conductive layer and an outer, second semi-conductive layer surrounding the first insulating layer. The second semi-conductive layer has at least two different earth points along the insulated conductor, the second semi-conductive layer has breaks located between consecutive earth points. A shielding device is located in each of said breaks for reducing amplification of the electric field strength produced at the breaks.