Covers the construction and dimensions for designs of single core cable having either aluminium or copper conductors, cross linked polyethylene (XLPE) extruded insulation, lead alloy sheath and medium density polyethylene (MDPE) oversheath. Test requirements and test methods are included which are intended to demonstrate the capability of the cable for operation at a sustained maximum conductor temperature of 90 deg C. The cable is designed to be suitable for a maximum short circuit temperature of 250 deg C. Cables conforming to this Specification are intended to be suitable for laying direct in ground, in ducts or in air.