1、 International Telecommunication Union ITU-T L.67TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (10/2006) SERIES L: CONSTRUCTION, INSTALLATION AND PROTECTION OF CABLES AND OTHER ELEMENTS OF OUTSIDE PLANT Small count optical fibre cables for indoor applications ITU-T Recommendation L.67 ITU-T Rec. L
2、.67 (10/2006) i ITU-T Recommendation L.67 Small count optical fibre cables for indoor applications Summary This Recommendation describes the characteristics, construction and test methods of small count optical fibre cables for indoor applications. Indoor optical fibre cables that contain three or m
3、ore fibres have been described in ITU-T Recommendation L.59. This Recommendation deals with small count optical fibre cable that contains one or two optical fibre(s). First, we describe the cable characteristics that are required if an optical fibre is to demonstrate sufficient levels of performance
4、. Then, a method is described for examining whether a cable has the required characteristics. The required conditions may differ according to the installation environment. Therefore, detailed test conditions of experiments must be agreed between a user and a supplier on the basis of the environment
5、in which a cable is to be used. Source ITU-T Recommendation L.67 was approved on 29 October 2006 by ITU-T Study Group 6 (2005-2008) under the ITU-T Recommendation A.8 procedure. ii ITU-T Rec. L.67 (10/2006) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized ag
6、ency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwid
7、e basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA
8、Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administra
9、tion and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions
10、are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the
11、possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of
12、the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest in
13、formation and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2008 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. L.67 (10/2006) iii CONTENTS Pag
14、e 1 Scope 1 2 References. 1 3 Definitions 2 4 Abbreviations and acronyms 2 5 Characteristics of optical fibres and cables 3 5.1 Optical fibres 3 5.2 Mechanical characteristics 3 5.3 Environmental conditions. 3 5.4 Fire safety . 4 6 Cable construction 4 6.1 Fibre protection 4 6.2 Cable element . 4 6.
15、3 Sheath . 5 6.4 Cable identification 5 7 Test methods. 5 7.1 Test methods for cable elements 5 7.2 Test methods for mechanical characteristics of cable 6 7.3 Test methods for environmental characteristics. 7 7.4 Test methods for fire safety 7 Appendix I Japanese experience Construction of small cou
16、nt optical fibre cables for indoor applications 8 Bibliography. 10 ITU-T Rec. L.67 (10/2006) 1 ITU-T Recommendation L.67 Small count optical fibre cables for indoor applications 1 Scope This Recommendation: refers to small count (one or two) optical fibre cables to be used for telecommunications net
17、works in buildings and houses; deals with mechanical and environmental characteristics of these small count optical fibre cables. The optical fibre dimensional and transmission characteristics, together with their test methods, should comply with IEC 60793-2-10, ITU-T G.652, ITU-T G.653, ITU-T G.654
18、, ITU-T G.655 and ITU-T G.656, which deal with a multi-mode graded index optical fibre and single-mode optical fibres respectively; deals with fundamental considerations related to optical fibre cable from mechanical and environmental points of view; acknowledges that some optical fibre cables may c
19、ontain metallic elements, for which reference should be made to the manual Outside plant technologies for public networks (see ITU-T L.1), and other L-series Recommendations; recommends that an optical fibre cable should be provided with cable end-sealing and protection during cable delivery and sto
20、rage, as is common for metallic cables. If splicing components have been factory installed they should be adequately protected. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation
21、. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references list
22、ed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T G.650.1 ITU-T Recommendation G.650.1 (2004), Definitions and test methods fo
23、r linear, deterministic attributes of single-mode fibre and cable. ITU-T G.651 ITU-T Recommendation G.651 (1998), Characteristics of a 50/125 m multimode graded index optical fibre cable. ITU-T G.652 ITU-T Recommendation G.652 (2005), Characteristics of a single-mode optical fibre and cable. ITU-T G
24、.653 ITU-T Recommendation G.653 (2006), Characteristics of a dispersion-shifted single-mode optical fibre and cable. ITU-T G.654 ITU-T Recommendation G.654 (2006), Characteristics of a cut-off shifted single-mode optical fibre and cable. ITU-T G.655 ITU-T Recommendation G.655 (2006), Characteristics
25、 of a non-zero dipersion-shifted single-mode optical fibre and cable. ITU-T G.656 ITU-T Recommendation G.656 (2006), Characteristics of a fibre and cable with non-zero dispersion for wideband optical transport. 2 ITU-T Rec. L.67 (10/2006) ITU-T L.1 ITU-T Recommendation L.1 (1988), Construction, inst
26、allation and protection of telecommunication cables in public networks. ITU-T L.46 ITU-T Recommendation L.46 (2000), Protection of telecommunication cables and plant from biological attack. IEC 60189-1 IEC 60189-1 (2007), Low-frequency cables and wires with PVC insulation and PVC sheath Part 1: Gene
27、ral test and measuring methods. IEC 60332-1-1 IEC 60332-1-1 (2004), Tests on electric and optical fibre cables under fire conditions Part 1-1: Test for vertical flame propagation for a single insulated wire or cable Apparatus. IEC 60332-3-24 IEC 60332-3-24 (2000), Tests on electric cables under fire
28、 conditions Part 3-24: Test for vertical flame spread of vertically-mounted bunched wires or cables Category C. IEC 60754-1 IEC 60754-1 (1994), Test on gases evolved during combustion of materials from cables Part 1: Determination of the amount of halogen acid gas. IEC 60754-2 IEC 60754-2 (1991), Te
29、st on gases evolved during combustion of electric cables Part 2: Determination of degree of acidity of gases evolved during the combustion of materials taken from electric cables by measuring pH and conductivity. IEC 60793-1-1 IEC 60793-1-1 (2002), Optical fibres Part 1-1: General and guidance. IEC
30、60793-1-32 IEC 60793-1-32 (2001), Optical fibres Part 1-32: Measurement methods and test procedures Coating strippability. IEC 60793-2-10 IEC 60793-2-10 (2007), Optical fibres Part 2-10: Product specifications Sectional specification for category A1 multimode fibres. IEC 60794-1-1 IEC 60794-1-1 (200
31、1), Optical fibre cables Part 1-1: Generic specification General. IEC 60794-1-2 IEC 60794-1-2 (2003), Optical fibre cables Part 1-2: Generic specification Basic optical cable test procedures. IEC 60794-2 IEC 60794-2 (2002), Optical fibre cables Part 2: Indoor cables Sectional specification. IEC 6079
32、4-2-10 IEC 60794-2-10 (2003), Optical fibre cables Part 2-10: Indoor cables Family specification for simplex and duplex cables. IEC 61034-1 IEC 61034-1 (2005), Measurement of smoke density of cables burning under defined conditions Part 1: Test apparatus. IEC 61034-2 IEC 61034-2 (2005), Measurement
33、of smoke density of cables burning under defined conditions Part 2: Test procedure and requirements. 3 Definitions For the purpose of this Recommendation, the definitions given in ITU-T G.650.1, ITU-T G.650.2 and ITU-T G.651 apply. 4 Abbreviations and acronyms None. ITU-T Rec. L.67 (10/2006) 3 5 Cha
34、racteristics of optical fibres and cables 5.1 Optical fibres Optical fibres described in IEC 60793-2-10, ITU-T G.652, ITU-T G.653, ITU-T G.654, ITU-T G.655 and ITU-T G.656 should be used. 5.2 Mechanical characteristics If mechanical forces (e.g., expanding, buckling, bending, torsion, crush and kink
35、) are applied, they may affect the performance of a fibre and a cable. This clause describes the relations between typical mechanical forces and cable performance. 5.2.1 Bending Cable bending during installation and operation may impose strain on fibres and this may affect fibre strength. Bending al
36、so causes a loss increase. Therefore, when designing a tensile member or limiting the installation conditions, the cable bending radius must be kept large enough to avoid any loss increase or fibre lifetime degradation. 5.2.2 Tensile strength Optical fibre cable is subjected to short-term loading du
37、ring manufacture and installation and may be affected by continuous static loading and/or cyclic loading during operation (e.g., temperature variation). Changes to the cable tension as a result of the various factors encountered by a cable during its service life can cause the differential movement
38、of the cable components. This effect needs to be considered in the cable design. Excessive cable tensile loading increases the optical loss and may cause increased residual strain in the fibre if the cable cannot relax. To avoid this, the maximum tensile strength determined by the cable construction
39、, especially as regards the design of the strength member, should not be exceeded. NOTE Where a cable is subjected to permanent loading during its operational life, the fibre should preferably not experience additional strain. 5.2.3 Crushing and impact The cable may be subjected to crushing and impa
40、ct both during its installation and operational life. This crushing and impact may increase the optical loss (permanently or during the time the stress is applied) and excessive stress may lead to fibre fracture. 5.2.4 Torsion Under the dynamic conditions encountered during installation and operatio
41、n, the cable may be subjected to torsion, resulting in residual strain in the fibres and/or sheath damage. Should this be the case, the cable design should allow a specified number of cable twists per unit length without any increase in fibre loss and/or sheath damage. 5.3 Environmental conditions T
42、he environmental conditions experienced by indoor cables may be less severe than those encountered by outdoor cables. However, the conditions may differ depending on the building. Therefore, if the environmental conditions are not clear, it is recommended that the same requirements be applied as tho
43、se used for outdoor cables. 5.3.1 Temperature variations During their operational lifetime, cables may be subjected to severe temperature variations. Under such conditions, the increase in fibre attenuation shall not exceed the specified limits. 4 ITU-T Rec. L.67 (10/2006) 5.3.2 Biotic damage The sm
44、all size of an optical fibre cable makes it vulnerable to rodent attack. Where rodents cannot be excluded, suitable and effective protection should be used. Further information is provided in ITU-T L.46. Effective protection can be provided by metallic barriers (steel tape or wire armouring), or non
45、-metallic barriers (e.g., fibreglass rods, glass yarns/tapes). 5.3.3 Vibration In buildings, it is assumed that there are various kinds of vibrations caused by such factors as construction, generators and elevators. Usually, cable elements are held in place by friction. Vibrations may cause this fri
46、ction to decrease. This in turn may cause cable elements to move, thus affecting the transmission or mechanical characteristics of the cables. The effects may be harsher when optical fibre cables are installed on a vertical pathway. Therefore, cables should be able to withstand these vibrations with
47、out failure or signal degradation. Care should be exercised, however, in the choice of installation method. 5.4 Fire safety Fire safety is an important problem in buildings and houses. There are two major issues. The first is that the cables and cable elements should have flame retardant characteris
48、tics. The second is that the cables and cable elements should not generate toxic gases or smoke when burning. Fire performance requirements may differ from country to country. Optical cables for indoor applications should comply with the fire safety regulations of each country or telecommunication c
49、arrier. 6 Cable construction 6.1 Fibre protection 6.1.1 Fibre primary coating Primary coated fibres must comply with relevant G.650-series of ITU-T Recommendations. 6.1.2 Buffered fibre When using a tight or semi-tight buffer (loosely applied), the following items should be requested: A tight buffer should be easily removable over a length of 15 to 25 mm for fibre splicing. A semi-tight buffer should be easily removable over a length of 300 to 20
