Abstract: An elongate flexible core 1 especially suitable for use in an optical cable to be employed as an aerial cable has in its outer circumferential surface circumferentially spaced, longitudinally extending grooves 3 in which optical fibres 34 will be loosely housed and comprises extruded plastics material and a multiplicity of longitudinally stressed elongate flexible non-metallic reinforcing element each substantially encapsulated in the extruded plastics material, the multiplicity of non-metallic reinforcing elements being substantially evenly distributed throughout the cross-sectional area of the core. The non-metallic reinforcing elements preferably extend helically around the axis of the core a long length of lay and preferably constitute 60 to 70% by volume of the extruded plastics material. The non-metallic reinforcing elements are preferably made of an aromatic polyamide and the plastics material may be a thermoplastics material, a thermosetting material or a thermotropic liquid crystalline polymer.

Abstract: An optical cable having a bore in which is loosely housed two helically extending optical fibre ribbons and which is filled with a greasy water-impermeable medium is manufactured by feeding four flexible cords of electrically insulating material into circumferentially spaced, longitudinally extending grooves in the outer surface of a stationary rigid tubular elongate guide of circular cross-section, helically lapping two optical fibre ribbons around the guide and the flexible cords so that the cords support the helically lapped ribbons, applying longitudinally to and transversely folding around the guide and the optical fibre ribbon a flexible strip of electrically insulating material to form a tube, introducing water-impermeable medium in a liquid or semi-liquid state through a bore in the guide and into the tube and extruding around the tube a sheath of electrically insulating material.