At&t Technologies, Inc.

At&t Bell Laboratories

American Telephone & Telegraph Co., At&t Bell Laboratories

Palmer D Thomas

Candido J Arroyo

Wendell G Nutt

Harold Wayne Friesen

James Robert Holman

David M Mitchell

Nicholas J Cogelia

Richard D Beggs

Jay T Loadholt, Iii

Emanuele Scalco

An optical fiber cable particularly suited for use in building distribution systems includes a core which comprises a plurality of coated optical fibers (22--22) with each being enclosed in a plastic buffer (26). The optical fibers are individually or collectively enclosed in a fibrous strength member. Over the strength member in each of several embodiments is provided an outer jacket comprising a plastic material having excellent resistance to flame spread and smoke evolution. The plastic material comprising the jacket is disposed about the strength member and decoupled sufficiently therefrom to avoid the introduction of microbending stresses in the optical fiber. This may be accomplished by vacuum sizing the plastic material which has been tubed over an advancing optical fiber core as the plastic material is being drawn down onto the strength member.

Optical fiber plenum cable and methods of making

A cable (20) which is particularly suited to the transmission of substantially error-free data at relatively high rates over relatively long distances includes at least two pairs of individually insulated conductors (42--43). Each pair of individually insulated conductors is enclosed individually in its own tubular member (51) comprising a plastic material. A metallic shield (60) encloses the tubular members, and in a preferred embodiment, a plastic jacket (80) encloses the shield. In the preferred embodiment, two pairs of voice communications conductors are disposed at opposed locations between the shield and the jacket. The thickness of the tubular member is such that each insulated conductor of each twisted pair is caused to be spaced from the shield a distance which is not less than one half the diameter of the metallic wire portion of each pair enclosed by the tubular member.

Local area network cable

A relatively small pair size cable (20) comprising at least one conductor (22) which is insulated with polyvinyl chloride plastic material is provided with a flame retardant, smoke suppressive sheath system (30). The sheath system has a relatively low thermal conductivity and provides a predetermined delay prior to the thermal decomposition of the conductor insulation. It includes a layer (31) of an impregnated woven glass material which has an air permeability that is sufficiently low to minimize gaseous flow through the layer of woven glass material and to delay heat transfer to the core for a predetermined time. The woven glass layer is wrapped about the core to have a longitudinal overlapped seam and is enclosed by an outer jacket (40) of a fluoropolymer plastic material which is extruded about the woven layer.

Flame-resistant plenum cable and methods of making

A relatively small pair size cable (20) comprising at least one conductor (22) which is insulated with polyvinyl chloride plastic material is provided with a flame retardant, smoke suppressive non-metallic sheath system (30). The sheath system has a relatively low thermal conductivity and provides a predetermined delay prior to the thermal decomposition of the conductor insulation. It includes an inner layer (31) of an aramid fibrous material which has a relatively high compressibility, a relatively low heat absorptivity, and a relatively low air permeability. The inner layer is enclosed by an outer jacket (40) of a fluoropolymer plastic material which is extruded about the inner layer.

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Tucker, GA, United States of America

Palmer D Thomas