| 摘要 |
The invention provides a communications cable comprising a plurality of cores through which communications signals can be transmitted, each core comprising a metallic conductor surrounded by a close-fitting sleeve of insulating material which is substantially free of halogenated polymers, the insulating material having a permittivity of no greater than 3, and comprising an outer layer of a non-foamed polymer surrounding a layer of foamed polymer, the outer layer containing a fire retardant, the layer of foamed polymer optionally surrounding a layer of non-foamed polymer, and wherein the region of the insulating material immediately adjacent the metallic conductor contains no fire retardant metal hydroxide and/or carbonate filler; an outer cable sheath disposed radially outwardly of and surrounding the cores, the outer cable sheath constituting a fire protection layer and being formed from an extrudable polymer containing a fire retardant material such as a metal hydroxide and/or carbonate filler; and optionally a metallic or metallised screening layer disposed between the cores and the outer cable sheath; but provided that no additional fire protection layer is disposed between the cores and the outer cable sheath.
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