GB2260216A - Fire-resistant electric cables - Google Patents

Fire-resistant electric cables Download PDF

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Publication number
GB2260216A
GB2260216A GB9120878A GB9120878A GB2260216A GB 2260216 A GB2260216 A GB 2260216A GB 9120878 A GB9120878 A GB 9120878A GB 9120878 A GB9120878 A GB 9120878A GB 2260216 A GB2260216 A GB 2260216A
Authority
GB
United Kingdom
Prior art keywords
sheath
laminate
cable
fire hazard
plastics
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB9120878A
Other versions
GB9120878D0 (en
GB2260216B (en
Inventor
Kenneth Malcolm Grainger
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nortel Networks Ltd
Original Assignee
Northern Telecom Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Northern Telecom Ltd filed Critical Northern Telecom Ltd
Priority to GB9120878A priority Critical patent/GB2260216B/en
Publication of GB9120878D0 publication Critical patent/GB9120878D0/en
Publication of GB2260216A publication Critical patent/GB2260216A/en
Application granted granted Critical
Publication of GB2260216B publication Critical patent/GB2260216B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00—Insulated conductors or cables characterised by their form
    • H01B7/17—Protection against damage caused by external factors, e.g. sheaths or armouring
    • H01B7/29—Protection against damage caused by extremes of temperature or by flame
    • H01B7/295—Protection against damage caused by extremes of temperature or by flame using material resistant to flame
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B11/00—Communication cables or conductors
    • H01B11/02—Cables with twisted pairs or quads

Landscapes

  • Insulated Conductors (AREA)

Abstract

A limited fire hazard (LFH) telecommunications cable (Fig. 1) comprises a transmission package (11) enclosed in a first LFH plastics sheath (13). The sheath 13 is enclosed in plastics metal laminate longitudinal tape (14) which is in turn coated with a further plastics LFH sheath (15). The further sheath (15) is bonded to the laminate tape (14). The package (11) may be wrapped in a polyester tape (12) and an identification tape (120) provided. The laminate provides a barrier to inhibit smoke from the package (11). <IMAGE>

Description

IMPROVEMENTS IN CABLES This invention relates to telecommunications cables and in particular to cables exhibiting limited fire hazard (LFH) properties.
A conventional telecommunications cable comprises a transmission pajckage sheathed in a plastics material such as polyvinyl chloride (PVC). Whilst these cables have proved satisfactory for many applications, it has been found that the sheath materials emit considerable quantities of toxic fumes in the event of a fire. This represents a significant hazard when the cable is located in a confined space, e.g. in a telephone exchange or in a tunnel, and for this reason a number of low fire hazard materials have been investigated. For example, cables have been manufactured from the so called zero-halogen plastics materials which emit only low toxicity fumes when exposed to a fire. The disadvantage of these materials are that they are more costly than the conventional PVC insulation.This cost disadvantage is a particular problem with the transmission package as a separate production line is required for the insulation of the conductor pairs.
The object of the present invention is to minimise or to overcome this disadvantage.
According to the invention there is provided a limited fire hazard (LFH) telecommunications cable, including a transmission package, a first (inner) limited fire hazard plastics sheath, a second (outer) limited fire hazard plastics sheath, and a plastics/metal laminate sheath disposed between which first and second sheaths are bonded to said outer sheath.
According to another aspect of the invention there is provided a method of manufacturing a limited fire hazard cable, the method including providing a transmission package, extruding a first sheath of a limited fire hazard material on to the transmission package, providing a plastics/metal laminate layer on the surface of the first sheath, protecting the laminate layer, and extruding a second sheath of a limited fire hazard material on to the structure whereby to provide a bond between the laminate layer and the second sheath.
An embodiment of the invention will now be described with reference to the accompanying drawings in which : Fig. 1 is a cross-sectional view of a limited fire hazard (LFH) telecommunications cable; and Figs. 2 and 3 show alternative cable constructions.
Referring to Fig. 1, the cable incorporates a transmission package generally indicated by the reference numeral 11 and comprising a number, e.g. ten, of insulated conductor pairs 110. The transmission package is wrapped with an insulating, e.g. polyester, tape 12. An identification tape 120 may be provided.
It will be appreciated that the transmission package 11 may comprise a standard package that may be employed in both LFH and non-LFH cables.
The taped transmission package is sheathed with an extruded inner sheath 13 of a limited fire hazard material such as AFR 4 compound.
This inner sheath 13 is provided with an aluminium/polyethylene laminate layer 14 which may be applied longitudinally. the laminate 14 is in turn coated with an outer sheath 15 of a limited fire hazard material, this outer sheath being bonded to the laminate layer 14.
This is effected by controlled preheating of the laminate 14 prior to extrusion of the outer sheath.
Figs 2 and 3 show similar cable constructions but having alternative transmission packages. Fig. 2 shows a cable having nineteen solid copper conductors 21 and being plastics insulated e.g. with a noryl extrusion coating 22. Fig. 3 shows a cable in which the transmission package comprises one hundred copper donductor pairs subdivided into ten separately tape wrapped pair units 31.
We have found that, in a fire situation, the laminate layer provides an effective barrier which inhibits smoke emission from the transmission package of the cable.

Claims (7)

CLAIMS.
1. A limited fire hazard (LFH) telecommunications cable, including a transmission package incorporating a plurality of insulated conductor pairs, a first (inner) limited fire hazard plastics sheath surrounding said transmission package, a second (outer) limited fire hazard plastics sheath, and a plastics/metal laminate sheath or layer disposed between said first and second sheaths and bonded to said second sheath, said laminate sheath, in use, providing a barrier for inhibiting smoke emission from the transmission package,
2. A cable as claimed in claim 1, wherein said laminate sheath comprises an aluminium/polyethylene laminate.
3. A cable as claimed in claim 1 or 2, wherein said laminate sheath is thermally bonded to the second sheath.
4. A cable as claimed in any one of claims 1 to 3, wherein said laminate sheath comprises a tape applied longitudinally to the cable.
5. A telecommunications cable substantially as described herein with reference to and as shown in Fig. 1, Fig. 2 or Fig. 3 of the accompanying drawings.
6. A method of manufacturing a limited fire hazard telecommunications cable, the method including providing a transmission package, comprising a plurality of inhibited conductor pairs, extruding a first sheath of a limited fire hazard material on to the transmission package, providing a plastics/metal laminate layer on the surface of the first sheath, protecting the laminate layer, and extruding a second sheath of a limited fire hazard material on to the preheated laminate layer whereby to provide a bond between that layer and the second sheath.
7. A method of manufacturing a telecommunications cable substantially as described herein with reference to and as shown in the accompanying drawings.
GB9120878A 1991-10-01 1991-10-01 Improvements in cables Expired - Fee Related GB2260216B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB9120878A GB2260216B (en) 1991-10-01 1991-10-01 Improvements in cables

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9120878A GB2260216B (en) 1991-10-01 1991-10-01 Improvements in cables

Publications (3)

Publication Number Publication Date
GB9120878D0 GB9120878D0 (en) 1991-11-13
GB2260216A true GB2260216A (en) 1993-04-07
GB2260216B GB2260216B (en) 1995-07-05

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB9120878A Expired - Fee Related GB2260216B (en) 1991-10-01 1991-10-01 Improvements in cables

Country Status (1)

Country Link
GB (1) GB2260216B (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0811992A2 (en) 1996-06-07 1997-12-10 B.N. Custom Cables Canada Inc. Cable with dual layer jacket
GB2327529A (en) * 1997-07-08 1999-01-27 City Electrical Factors Ltd Fire-resistant electric cable
US7696437B2 (en) 2006-09-21 2010-04-13 Belden Technologies, Inc. Telecommunications cable
US7923638B2 (en) * 2001-06-14 2011-04-12 Prysmian Telecom Cables & Systems Australia Pty Ltd Communications cable provided with a crosstalk barrier for use at high transmission frequencies
US8198536B2 (en) 2005-12-09 2012-06-12 Belden Inc. Twisted pair cable having improved crosstalk isolation

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7154043B2 (en) 1997-04-22 2006-12-26 Belden Technologies, Inc. Data cable with cross-twist cabled core profile
US6074503A (en) 1997-04-22 2000-06-13 Cable Design Technologies, Inc. Making enhanced data cable with cross-twist cabled core profile

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1500121A (en) * 1976-01-09 1978-02-08 Pirelli General Cable Works Fire resistant electric cables
GB1583956A (en) * 1977-03-10 1981-02-04 Bicc Ltd Electric cables
GB1583957A (en) * 1977-03-10 1981-02-04 Bicc Ltd Electric cables
EP0150879A2 (en) * 1984-01-27 1985-08-07 Philips Patentverwaltung GmbH Flame resistant coaxial high frequency cable
EP0380244A1 (en) * 1989-01-27 1990-08-01 AT&T Corp. Building cables which include non-halogenated plastic materials

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1500121A (en) * 1976-01-09 1978-02-08 Pirelli General Cable Works Fire resistant electric cables
GB1583956A (en) * 1977-03-10 1981-02-04 Bicc Ltd Electric cables
GB1583957A (en) * 1977-03-10 1981-02-04 Bicc Ltd Electric cables
EP0150879A2 (en) * 1984-01-27 1985-08-07 Philips Patentverwaltung GmbH Flame resistant coaxial high frequency cable
EP0380244A1 (en) * 1989-01-27 1990-08-01 AT&T Corp. Building cables which include non-halogenated plastic materials

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0811992A2 (en) 1996-06-07 1997-12-10 B.N. Custom Cables Canada Inc. Cable with dual layer jacket
EP0811992A3 (en) * 1996-06-07 1998-11-18 B.N. Custom Cables Canada Inc. Cable with dual layer jacket
US7276664B2 (en) 1996-06-07 2007-10-02 Belden Technologies, Inc. Cable with dual layer jacket
GB2327529A (en) * 1997-07-08 1999-01-27 City Electrical Factors Ltd Fire-resistant electric cable
GB2327529B (en) * 1997-07-08 2001-07-04 City Electrical Factors Ltd Electrical cable
US7923638B2 (en) * 2001-06-14 2011-04-12 Prysmian Telecom Cables & Systems Australia Pty Ltd Communications cable provided with a crosstalk barrier for use at high transmission frequencies
US8198536B2 (en) 2005-12-09 2012-06-12 Belden Inc. Twisted pair cable having improved crosstalk isolation
US7696437B2 (en) 2006-09-21 2010-04-13 Belden Technologies, Inc. Telecommunications cable

Also Published As

Publication number Publication date
GB9120878D0 (en) 1991-11-13
GB2260216B (en) 1995-07-05

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Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee

Effective date: 20021001