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A high voltage electrical power cable with a longitudinally folded, smooth or corrugated, metal strip around a plurality of layers around the conductor and a water swellable material at least at the adjacent edges of the strip. Preferably, the water swellable material is included with a polymeric ma

A high voltage electrical power cable with a longitudinally folded, smooth or corrugated, metal strip around a plurality of layers around the conductor and a water swellable material at least at the adjacent edges of the strip. Preferably, the water swellable material is included with a polymeric material which is flowable at a temperature at least as low as 100°C., the polymeric material has a 100 gram needle penetration value in the range from 50-100 tenths of a millimeter at 25°C. and the water swellable material has a particle size not greater than 200 microns.

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In an electrical power cable comprising a stranded conductor formed by a plurality of wires stranded together and in conductive contact with adjacent wires, particles of water swellable material within any interstices in said conductor, a semi-conductive stress control layer around said conductor, a

In an electrical power cable comprising a stranded conductor formed by a plurality of wires stranded together and in conductive contact with adjacent wires, particles of water swellable material within any interstices in said conductor, a semi-conductive stress control layer around said conductor, a layer of insulation around said stress control layer, a semi-conductive insulation shield of substantially constant cross-sectional radius around said insulation and a longitudinally folded strip of metal with circumferentially spaced edges around said insulation shield, said strip being corrugated transversely to its length to provide outwardly extending humps and intermediate valleys and having its edges extending longitudinally of said cable and being adjacent to each other but with a space at the face of one of said edges between it and the adjacent portion of the strip, the improvement comprising particles of a water swellable material at least in said space at the adjacent edges of said strip. A method of making an electrical power transmission cable having a plurality of layers of uninsulated wires thereby providing an outer layer of wires and an inner layer or layers of wires, said method comprising: bringing together said wires into conductive contact while applying flowable polymeric compound around at least the said wires forming the inner layer or layers; putting particles of a water swellable material having a particles size not greater than 200 microns into contact with said polymeric compound which is applied around said wires forming said inner layer or layers; extruding a first layer of semi-conductive material around said wires; extruding a layer of insulation around said layer of semi-conductive material; extruding a second layer of semi-conductive material of substantially constant cross-sectional radius around said layer of insulation; longitudinally folding a metallic strip around said second layer so as to provide overlapping edge portions extending longitudinally of the cable said edges being adjacent to each other but with a space at the face of one of said edges between it and the adjacent portion of the strip; and applying particles of a water swellable material adjacent the edge portions of said strip prior to completion of the folding of said strip so as to provide said particles at least in said space.