Abstract: Enclosure for electrical apparatus comprising a first hollow sleeve of insulating material around which is positioned a second sleeve comprising an inner layer of insulating material and an outer layer of conductive material (normally connected to earth, e.g. a cable shield). This construction locates the major discontinuities of the material enclosure wall between layers of the insulating materials thus reducing the electrical stresses which could lead to insulation failure. The first sleeve may have an innermost laminated layer of stress grading material. Electrically conducting material may be present on the inner surface of the first sleeve to form a Faraday cage. Further sleeves may be interposed between the first and second sleeves to increase the insulation for higher voltages, and void filling compound may be used further to improve the electrical conditions within the enclosure.