Abstract: An electrical feed-through apparatus is prevents or substantially reduces partial corona discharges in penetrators for high voltage supply for underwater facilities. A flange of a first thickness has an opening providing a passage between first and second oppositely located sides of the flange. An elongated tube of a solid, electrically insulating material has a first length greater than the first thickness, and is positioned in the passage, with first and second parts of the tube protruding from the first and second sides of the flange, respectively. First and second attachment sleeves are positioned on the tube and are attached to the first and second parts of the tube, respectively, at a distance from respective first and second ends of the tube. The sleeves are attached to the respective first and second oppositely located sides of the flange.