Abstract: An insulation of cross-linked polymer is extruded about a cable conductor and cross-linked by means of heating in a vulcanization tube. The heating is effected by radiation energy, at least the main part of the radiation having wavelengths between 0.76 .mu.m and 4 .mu.m and a tube which is permeable to the radiation being used as vulcanization tube.

Abstract: Electrical cables having cross-linked polymer insulations are spliced by heating the insulations nearest the ends to be joined to a temperature such that the cross-linked polymers become amorphous, then expanding and axially moving the insulations away from the conductors such that they can be joined, then cooling the displaced insulations, then joining the conductors, and then reheating the insulations such that they return to generally their original shape and position around the conductors. The prior art technique of bevelling the insulators nearest the cable ends prior to conductor joining, with concurrent waste of insulating material, is made unnecessary.

Abstract: For joining two cables which have an insulation of a cross-linked linear polymer such as polyethylene, the insulation on each of the two ends to be connected is tapered, the ends of the conductors are then secured to each other, and the joint is wrapped with a tape of the same linear polymer containing a cross-linking agent. The wrapping is enclosed in a tube of relatively rigid material, which is then enclosed in a tube of flexible material. The joint is then enclosed in a casing and simultaneously subjected to heating by an electric heating arrangement and to all-sided pressure exerted by a fluid, which may be a gas or a liquid such as silicone oil.