Methods of making high voltage electrical insulators and oil-less bushings

A method of making a conductive insulated oil-less bushing, said method comprising steps as follows:

• placing a sheath of an essentially completely unvulcanized elastomer on a core, the core being a conductive rod with paper windings thereabout, the paper windings having metal oil interposed therein, and the elastomer being selected from the group consisting of ethylene-propylene-diene monomer rubber, ethylene-propylene monomer rubber and butyl rubber, said placement being performed at a temperature below the vulcanizing temperature of said sheath,
• impregnating said windings with hardenable epoxy resin, said resin being cured at below sheath vulcanizing temperature,
• mounting at essentially room temperature a plurality of fully vulcanized elastomeric sheds on the sheath, the sheds being of a material of the same or similar formulation as used for the sheath, and
• then heating the core, sheath and shed assembly to between 140.degree. to 200.degree. C. to vulcanize the sheath and to bond same to the core and to the sheds so as to form said conductive oil-less bushing.