Abstract: A high voltage (HV) apparatus insulated with an insulating gel includes at least two electrically conductive elements, such as a head transformer cover, a head housing base, a core casing, a primary conductor, bottom external housing, a bottom support flange, and/or a core. At least one of the electrically conductive elements has a coating made of solid insulating material separating the surface of the conductive element from the insulating gel and adapted for limiting electron emission from the conductive elements into the insulating gel.