GB/Z 41287.1-2022Optical fiber telecommunication cable for use in premises cabling - Part 1:Optical fibre cables for duct and directly buried application (English PDF)

Foreword

This document was drafted in accordance with the rules given in GB/T 1.1-2020, Directives for standardization - Part 1: Rules for the structure and drafting of standardizing documents.

This document is Part 1 of GB/Z 41287, Optical fibre telecommunication cable for use in premises cabling. The following parts of GB/Z 41287 have been published: Part 1: Optical fibre cables for duct and directly buried application; Part 2: Optical fibre cables for self-supporting aerial application.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The issuing body of this document shall not be held responsible for identifying any or all such patent rights.

This document was proposed by and is under the jurisdiction of the Ministry of Industry and Information Technology of the People's Republic of China.

The drafting organizations of this document are Chengdu Datang Cable Co., Ltd., Chengdu Tairui Communication Equipment Testing Co., Ltd., Sichuan Huiyuan Optical Communications Co., Ltd., Yangtze Optical Fibre and Cable Joint Stock Limited Company, Jiangsu Hengtong Optic-Electric Co., Ltd., FiberHome Technologies Group Co., Ltd., Jiangsu Junzhi Technology Co., Ltd., China Academy of Information and Communications Technology, Chengdu Hengtong Optical Communication Co., Ltd., Jiangsu Etern Co., Ltd., China Academy of Telecommunications Technology Co., Ltd. and Tongding Interconnection Information Co., Ltd.

The main drafters of this document are Huang Kun, Peng Yuan, Xue Mengchi, Liu Tai, Lv Jie, Xu Jiangbo, Song Zhituo, Shi Bin, Luo Yi, Xiong Zhuang, Liu Xiangrong, Wang Yaoming, Chen Xiaohong, Wang Zemin, Yuan Fan, Li Jichao, Gao Hua, Xiao Rengui and Guo Zhihong.

Introduction

An optical fibre cable for use in premises cabling is the section of cable in the access network between the user access point and the user-side termination point (for example a campus distributor or building distributor) or the user optical node; it usually enters from outdoors and terminates indoors. At present, premises cabling optical fibre cables have different structural and performance requirements depending on the installation method.

GB/Z 41287, Optical fibre telecommunication cable for use in premises cabling, is divided according to the installation method of the cable into two parts: Part 1: Optical fibre cables for duct and directly buried application, which aims to regulate the structure and performance requirements of telecommunication premises cabling optical fibre cables installed in ducts and by direct burial; Part 2: Optical fibre cables for self-supporting aerial application, which aims to regulate the structure and performance requirements of telecommunication premises cabling optical fibre cables installed as self-supporting aerial cables.

1 Scope

This document specifies the types, specifications, structure and materials, optical fibre characteristics, mechanical performance, environmental performance and other properties of optical fibre telecommunication cables for use in premises cabling installed in ducts and by direct burial.

This document applies to outdoor premises cabling optical fibre cables for duct and directly buried application running from the user access point to the user-side termination point (for example a campus distributor or building distributor) or to the user optical node.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition (including any amendments) applies.

GB/T 6995.2 Methods for identification and marking of wires and cables - Part 2: Standard colours; GB/T 7424.2-2008 Generic specification for optical fibre cables - Part 2: Basic test procedures for optical cables; GB/T 9771 (all parts) Single-mode optical fibre for telecommunication; GB/T 12357.1-2015 Multimode optical fibres for telecommunication - Part 1: Characteristics of category A1 multimode fibres; GB/T 15065 Black polyethylene plastics for wires and cables; GB/T 15972 (all parts) Specifications for optical fibre test methods; GB/T 15972.22-2008 Specifications for optical fibre test methods - Part 22: Measurement methods and test procedures for dimensions - Length.

GB/T 18380.12-2008 Tests on electric and optical fibre cables under fire conditions - Part 12: Test for vertical flame propagation for a single insulated wire or cable - Procedure for 1 kW pre-mixed flame; GB/T 18380.35-2008 Tests on electric and optical fibre cables under fire conditions - Part 35: Test for vertical flame spread of vertically-mounted bunched wires or cables - Category C; GB/T 26572-2011 Requirements of concentration limits for certain restricted substances in electrical and electronic products; GB/T 29233-2012 Single-mode outdoor optical fibre cables for telecommunication for duct, directly buried and non-self-supporting aerial installation.

YD/T 629.1 Monitoring methods of optical fibre transmission attenuation changes - Transmitted power monitoring method; YD/T 629.2 Monitoring methods of optical fibre transmission attenuation changes - Backscattering monitoring method; YD/T 837.3-1996 Test methods for polyolefin insulated, aluminium-polyethylene laminated sheathed local telecommunication cables with copper conductors - Part 3: Test methods for mechanical and physical properties; YD/T 837.4-1996 same series - Part 4: Test methods for environmental performance; YD/T 901-2018 Stranded loose tube filled outdoor optical fibre cables for telecommunication; YD/T 908 Designation method for optical fibre cable types; YD/T 979 Technical requirements and test methods for optical fibre ribbons; YD/T 1113 Halogen-free low-smoke flame-retardant materials for telecommunication cables and optical fibre cables; YD/T 1258.1-2015 Indoor optical fibre cable series - Part 1: General; YD/T 1997.2-2015 Drop optical fibre cables for telecommunication - Part 2: Round cables; YD/T 2965 Characteristics of bending loss insensitive multimode optical fibres.

3 Terms and definitions

For the purposes of this document, the following terms and definitions apply.

3.1 campus. An area containing one or more buildings.

3.2 campus distributor. A distributor from which the campus backbone cabling emanates.

3.3 building distributor. A distributor that terminates the building backbone cable and can be connected to the campus backbone cable.

3.4 cables for use in premises cabling. The section of optical fibre cable in the access network between the user access point and the user-side termination point (for example a campus distributor or building distributor) or the user optical node. Note: it usually enters from outdoors and terminates indoors. Hereinafter referred to as premises cable.

3.5 small size-cables for use in premises cabling. Premises cabling optical fibre cables with a compact, small structure. Note: such cables have various structures and are relatively small in size compared with conventional outdoor optical fibre cables, for example air-blown micro cables, butterfly (flat) drop cables and round drop cables. Hereinafter referred to as small size premises cable.

3.6 fibre optical cable elements. Structural units of an optical fibre cable made up of optical fibres. Note: they form the core component of the cable.

4 Classification

4.1 General. In this document the cable types and specifications are classified and the type designations are compiled in accordance with YD/T 908.

4.2 Types. The specific structural types of the cable are specified in the relevant product standards.

4.3 Specifications. 4.3.1 The optical fibres in the cable shall be category B1.1, B1.3 and B6 single-mode fibres complying with GB/T 9771 (all parts), or category A1a.1a, A1a.2a, A1a.3a and A1b multimode fibres complying with GB/T 12357.1-2015, or category A1a.1b, A1a.2b and A1a.3b bending loss insensitive multimode fibres complying with YD/T 2965; the correspondence between fibre types and characteristic codes is given in Annex A.

Note to 4.3.1: B1.1 is non-dispersion-shifted single-mode fibre; B1.3 is extended-wavelength-band non-dispersion-shifted single-mode fibre; B6 is bending loss insensitive single-mode fibre for the access network, divided into four subcategories B6.a1, B6.a2, B6.b2 and B6.b3. A1a is 50/125 um graded-index multimode fibre, divided by bandwidth grade into A1a.1, A1a.2 and A1a.3, and by macrobending loss grade A1a.1 is subdivided into A1a.1a and A1a.1b, A1a.2 into A1a.2a and A1a.2b, and A1a.3 into A1a.3a and A1a.3b; A1a.1a, A1a.2a and A1a.3a are ordinary multimode fibres and A1a.1b, A1a.2b and A1a.3b are bending loss insensitive multimode fibres. A1b is 62.5/125 um graded-index multimode fibre.

4.3.2 The fibre count of the cable should be 1, 2, 4, 6, 8, 12, 16, 24, 36, 48, 60, 72, 96, 120 or 144. Other fibre counts agreed between supplier and purchaser may also be used.

5 Structure and materials

5.1 General. The cable structure shall provide reliable protection for the optical fibres during transport, storage, installation and operation of the cable, and maintain the specified optical and transmission performance of the fibres throughout the whole service life of the cable.

5.2 Optical fibre elements. 5.2.1 The cable may be made up of discrete fibres, fibre bundles, fibre ribbons or other suitable fibre elements. 5.2.2 Discrete fibres may form elements with a tight-buffered or loose-tube structure; fibre bundles and fibre ribbons should use a loose-tube structure; where a slotted core or similar structure is used, the fibre bundles or ribbons should have no tight-buffer or loose-tube protective layer; other suitable ways of forming the elements may also be used. 5.2.3 The identification of the fibre elements in the cable shall comply with 6.3.3 and 6.3.4 of GB/T 29233-2012, and the colours shall comply with GB/T 6995.2.

5.3 Materials of optical fibre elements. 5.3.1 The tight-buffer material should be polyamide, polyvinyl chloride, polyester elastomer, flame-retardant polyolefin, UV-cured resin, etc. 5.3.2 The loose tube should be made of thermoplastic materials such as polybutylene terephthalate (PBT), modified polypropylene (PP) or modified polycarbonate (PC); composite materials may also be used to increase the mechanical strength of the tube. The tube may be filled with a thixotropic compound or other suitable water-blocking material.

5.4 Strength members. Cables for duct and direct burial installation shall use suitable strength members according to the environment; they may be metallic or non-metallic.

5.5 Cable core. 5.5.1 The cable core may be of central tube, stranded, bundle, slotted core or other appropriate structure, suitable for duct or direct burial installation. Note: a bundle-type core is a core assembled from several fibre bundles (sheathed or coated fibre bundles) from which single fibres can easily be separated. 5.5.2 The slotted core unit of a slotted core structure should be a grooved cylinder made of a central strength member and polyolefin plastic. 5.5.3 The cable should be water-blocked over its entire cross-section, using filling compound, dry water-swellable materials or other suitable materials applied in a suitable manner. Water-blocking materials shall be odourless, non-toxic, harmless to health and compatible with the cable materials they contact.

5.6 Sheath. 5.6.1 The cable sheath comprises the sheath and, where present, the outer protective layer. 5.6.2 The surface of the sheath and of any outer protective layer shall be smooth, with no bubbles, sand holes or cracks visible to the naked eye in any cross-section. 5.6.3 The sheath should include a metallic moisture barrier and a plastic sheath. The metallic moisture barrier shall comply with 6.7 of GB/T 29233-2012. The plastic sheath may be polyethylene, low-smoke halogen-free flame-retardant polyolefin, flame-retardant polyethylene, etc. Polyethylene sheath material shall comply with GB/T 15065; low-smoke halogen-free flame-retardant polyolefin with YD/T 1113; flame-retardant polyethylene with Annex C of YD/T 1997.2-2015. Other suitable sheath materials may be used when required by the user, with performance specified in the relevant product standard.

5.6.4 The outer protective layer of directly buried cables should be a longitudinally applied corrugated steel tape armour with polyethylene sheath, or a steel wire armour with polyethylene sheath. 5.6.5 Sheath dimensions and performance are specified in the relevant product standard. 5.6.6 The outer sheath should be black; when required by the user it may be of another colour or carry coloured stripes, the colour being agreed between supplier and purchaser. 5.6.7 Where low friction is required for duct premises cables, it is agreed between supplier and purchaser; the dynamic friction coefficient test method may refer to Annex B. 5.6.8 Rodent and/or termite protection requirements are agreed between supplier and purchaser.

5.7 Flame-retardant structure. The outer sheath of flame-retardant cables should be low-smoke halogen-free flame-retardant polyolefin or flame-retardant polyethylene. Other components such as strength members, water-blocking fillers, fillers and tapes should be non-combustible or flame-retardant materials, so that the cable passes the specified fire tests.

5.8 Standard manufacturing length. The nominal standard manufacturing lengths should be 500 m, 1 000 m, 2 000 m and 3 000 m, with a tolerance of 0 % to +5 %. Delivery lengths should be the standard manufacturing length or lengths agreed between supplier and purchaser.

6 Performance requirements and tests

6.1 Characteristics and tests of optical fibres in the cable. 6.1.1 Single-mode fibre characteristics. 6.1.1.1 The dimensional parameters and mechanical properties of single-mode fibres shall comply with GB/T 9771 (all parts). 6.1.1.2 The cable cut-off wavelength lambda_cc of single-mode fibres shall be at most 1 260 nm. 6.1.1.3 The attenuation grades and coefficients of cabled single-mode fibres shall comply with Table 1; the correspondence of fibre types and characteristic codes is in Table A.1. 6.1.1.4 The macrobending loss of single-mode fibres shall comply with Table 2. 6.1.1.5 The chromatic dispersion of fibres before cabling shall comply with GB/T 9771 (all parts).

Table 1 (maximum attenuation coefficient of cabled single-mode fibre, dB/km, grade I / grade II): B1.1 - 1 310 nm 0.38/0.40, 1 550 nm 0.24/0.30, 1 625 nm 0.28/0.40; B1.3 - 1 310 nm 0.38/0.40, 1 383 nm 0.38/0.40, 1 550 nm 0.24/0.30, 1 625 nm 0.28/0.40; B6.a1 and B6.a2 - 1 310 nm 0.38/0.40, 1 383 nm 0.38/0.40, 1 550 nm 0.24/0.30, 1 625 nm 0.28/0.40; B6.b2 and B6.b3 - 1 310 nm 0.50/0.60, 1 550 nm 0.30/0.40, 1 625 nm 0.40/0.50. Note: products are inspected only at the wavelengths required by the user.

Table 2 (macrobending loss of single-mode fibre, maximum): B1.1 and B1.3 - radius 30 mm, 100 turns, 1 625 nm 0.1 dB (no value at 1 550 nm). B6.a1 - 15 mm, 10 turns: 0.25 dB at 1 550 nm, 1.0 dB at 1 625 nm; 10 mm, 1 turn: 0.75 dB / 1.5 dB. B6.a2 and B6.b2 - 15 mm, 10 turns: 0.03 dB / 0.1 dB; 10 mm, 1 turn: 0.1 dB / 0.2 dB; 7.5 mm, 1 turn: 0.5 dB / 1.0 dB. B6.b3 - 10 mm, 1 turn: 0.03 dB / 0.1 dB; 7.5 mm, 1 turn: 0.08 dB / 0.25 dB; 5 mm, 1 turn: 0.15 dB / 0.45 dB.

6.1.2 Multimode fibre characteristics. 6.1.2.1 The dimensional parameters and mechanical properties of A1a.1a, A1a.2a, A1a.3a and A1b multimode fibres shall comply with GB/T 12357.1; those of A1a.1b, A1a.2b and A1a.3b bending loss insensitive multimode fibres shall comply with YD/T 2965. 6.1.2.2 The numerical aperture shall comply with Table 3: A1a 0.200 +/- 0.015; A1b 0.275 +/- 0.015. 6.1.2.3 The transmission characteristics shall comply with Table 4; the correspondence with characteristic codes is in Tables A.2 and A.3.

Table 4 (multimode transmission characteristics; attenuation maximum in dB/km at 850 nm / 1 300 nm, modal bandwidth minimum in MHz.km at 850 nm / 1 300 nm): A1a.1a - attenuation grade 1: 2.4/0.7, grade 2: 3.0/1.0, grade 3: 3.5/1.5; bandwidth grades 1 to 3 at 850 nm: 200, 500, 800; grades 1 to 5 at 1 300 nm: 200, 500, 800, 1 000, 1 200. A1a.1b - 2.5/0.8; bandwidth 500/500. A1a.2a and A1a.2b - 2.5/0.8; bandwidth at 850 nm 1 500 (effective modal bandwidth 2 000), at 1 300 nm 500. A1a.3a and A1a.3b - 2.5/0.8; bandwidth at 850 nm 3 500 (effective modal bandwidth 4 700), at 1 300 nm 500. A1b - attenuation 2.8 and 3.5 at 850 nm, 0.7, 1.0 and 1.5 at 1 300 nm; bandwidth at 850 nm 100, 200, 500, 800; at 1 300 nm 200, 500, 800, 1 000. Values without footnote are overfilled launch bandwidths.

6.1.2.4 The macrobending loss of multimode fibres shall comply with: a) for A1a.1a, A1a.2a and A1a.3a fibres loosely wound 2 turns at a radius of 15 mm, the macrobending loss limit measured at 850 nm and 1 300 nm is 1.0 dB; if this is exceeded, the loss for 100 turns at a radius of 37.5 mm at 850 nm and 1 300 nm shall not exceed 0.5 dB; b) for A1b fibres loosely wound 100 turns at a radius of 37.5 mm, the loss at 850 nm and 1 300 nm shall not exceed 0.5 dB; c) A1a.1b, A1a.2b and A1a.3b fibres shall comply with Table 5: radius 7.5 mm, 2 turns - 0.2 dB at 850 nm and 0.5 dB at 1 300 nm; radius 15 mm, 2 turns - 0.1 dB and 0.3 dB; radius 37.5 mm, 100 turns - 0.5 dB and 0.5 dB (maximum values). 6.1.3 Fibre performance tests. Unless otherwise specified, fibre tests are carried out according to GB/T 15972 (all parts).

6.2 Characteristics and tests of tight-buffered fibres in the cable. 6.2.1 Except that no requirement is set for the outer diameter tolerance, the structure, mechanical and environmental performance of tight-buffered fibres shall comply with Annex A of YD/T 1258.1-2015. 6.2.2 Tests are carried out using the relevant test methods in Annex A of YD/T 1258.1-2015. 6.3 Characteristics and tests of fibre ribbons in the cable. 6.3.1 The structure, dimensions, mechanical and environmental performance of fibre ribbons shall comply with YD/T 979. 6.3.2 Tests are carried out according to the test methods in YD/T 979.

6.4 Sheath performance and tests. 6.4.1 The mechanical and physical properties of the sheath shall comply with Table 6 (values for LLDPE / MDPE / HDPE / LSZH / flame-retardant polyethylene): tensile strength before ageing minimum 10.0 / 12.0 / 16.0 / 10.0 / 12.5 MPa; change after ageing |TS| maximum 20 / 20 / 25 / 20 / 20 %; elongation at break before ageing minimum 350 / 350 / 350 / 125 / 300 %; after ageing minimum 300 / 300 / 300 / 100 / 250 %; change |EB| maximum 20 %; ageing at 100 +/- 2 degC for 24 x 10 h. Heat shrinkage maximum 5 %, at 100 +/- 2 degC (LLDPE), 115 +/- 2 degC (MDPE, HDPE), 85 +/- 2 degC (LSZH) for 4 h and 100 +/- 2 degC for 2 h (flame-retardant polyethylene). Environmental stress cracking resistance (50 degC, 96 h): 0/10 failures. LLDPE, MDPE, HDPE and LSZH denote linear low-density, medium-density and high-density polyethylene and low-smoke halogen-free flame-retardant polyolefin.

6.4.2 Sheath tests are carried out according to Table 7: peel strength of bonded sheath - requirement 4.3.2.2 of YD/T 901-2018, method 4.9 of YD/T 837.3-1996; tensile strength and elongation at break before and after ageing - Table 6 items 1 and 2, method 4.10 and 4.11 of YD/T 837.3-1996; heat shrinkage - Table 6 item 3, method 4.12 of YD/T 837.3-1996; environmental stress cracking resistance - Table 6 item 4, method 4.1 of YD/T 837.4-1996.

6.5 Mechanical performance and tests. 6.5.1 Tensile performance. 6.5.1.1 The cable shall pass test method E1 of GB/T 7424.2-2008; the allowable tensile force shall comply with Table 8. 6.5.1.2 Fibre strain, attenuation change and cable strain under tension shall comply with Table 9. Table 8 (minimum values): duct small size premises cable - coefficient A 1.0 or 1.5 (A = 1 for air blowing, 1.5 for pulling), short-term tensile F_ST = A x G, long-term F_LT = 30 % x F_ST, short-term crush F_SC 1 000 N/100 mm, long-term crush F_LC 300 N/100 mm; outdoor duct cable - A 1.0, F_ST 1 500 N or A x G (whichever is greater, G being the weight of 1 km of cable in N), F_LT 600 N, F_SC 1 500 N/100 mm, F_LC 750 N/100 mm; outdoor directly buried cable - F_ST 3 000 N, F_LT 1 000 N, F_SC 3 000 N/100 mm, F_LC 1 000 N/100 mm.

Table 9 (allowable changes under tension, fibre strain for discrete fibres / fibres in ribbons): short-term tension - small size duct cable <= 0.4 % / <= 0.4 %; outdoor duct cable <= 0.3 % / <= 0.4 %; outdoor buried cable <= 0.3 % / <= 0.4 %. Long-term tension - small size duct cable <= 0.2 % / <= 0.2 %; outdoor duct cable <= 0.1 % / <= 0.2 %; outdoor buried cable <= 0.1 % / <= 0.2 %, with no obvious additional attenuation. After unloading: fibres of small size premises cables shall show no obvious residual additional attenuation; fibres of outdoor duct and buried cables shall show no obvious residual strain and no obvious residual additional attenuation, and residual cable strain shall not exceed 0.08 %.

6.5.2 Crush performance. 6.5.2.1 The cable shall pass test method E3 of GB/T 7424.2-2008 with the allowable crush forces of Table 8. 6.5.2.2 Under the allowable long-term crush force the fibres shall show no obvious additional attenuation; under the allowable short-term crush force the fibres shall not break and the sheath shall not crack, and after removal of the short-term force the fibres shall show no obvious residual additional attenuation. 6.5.3 Allowable bending radius. 6.5.3.1 The bending radius shall comply with Table 10; special structures are agreed between supplier and purchaser. Table 10 (sheath types Y, U, V, H, A, S, F, W): without outer protective layer or with types 03, 04 - dynamic bending (installation) 20D, static bending (operation) 10D; types 53, 54 - 25D and 12.5D. Sheath and outer layer types follow YD/T 908; D is the cable outer diameter or the minor axis of a non-circular cable. 6.5.3.2 Under dynamic bending the fibres shall not break, the sheath shall not crack and there shall be no residual additional attenuation afterwards; under static bending there shall be no obvious additional attenuation and the sheath shall not crack.

6.5.4 Impact. 6.5.4.1 The cable shall pass test method E4 of GB/T 7424.2-2008 according to Table 11, with at least 500 mm between impact points. Table 11: hammer drop height 1 m, impact surface radius 12.5 mm, 3 impact points, 1 impact per point; hammer mass 100 g for small size duct cable, 450 g for outdoor duct cable, 1 000 g for outdoor buried cable. 6.5.4.2 After impact the sheath shall not crack; fibres in loose-structure cables shall show no obvious residual additional attenuation; in tight-structure cables the residual additional attenuation shall not exceed 0.4 dB for single-mode and 0.6 dB for multimode fibres.

6.5.5 Torsion. 6.5.5.1 The cable shall pass test method E7 of GB/T 7424.2-2008 according to Table 12: twist length 1 000 mm, 5 cycles; small size duct cable +/-180 deg with 20 N axial load; outdoor duct cable +/-180 deg with 150 N; outdoor buried cable +/-90 deg with 250 N. 6.5.5.2 After torsion the sheath shall not crack; at the extreme twist position the fibres shall show no obvious additional attenuation and after the test no obvious residual additional attenuation.

6.5.6 Tests. 6.5.6.1 Unless otherwise specified, mechanical performance is verified using the relevant methods of GB/T 7424.2-2008. 6.5.6.2 The monitoring wavelength is 1 550 nm for B1.1, B1.3 and B6 single-mode fibres and 1 300 nm for A1a.1a, A1a.2a, A1a.3a, A1b and A1a.1b, A1a.2b, A1a.3b multimode fibres. 6.5.6.3 Attenuation changes should be measured by the transmitted power monitoring method of YD/T 629.1, with measurement uncertainty not exceeding +/-0.03 dB for single-mode and +/-0.12 dB for multimode fibres; changes within these limits are judged as no obvious change, and where an attenuation change is allowed the limit already includes this uncertainty. 6.5.6.4 Fibre strain should be monitored by the phase-shift method of Annex C of GB/T 15972.22-2008 with uncertainty not exceeding +/-0.01 %; measured strain not greater than 0.01 % is judged as no obvious strain, and allowed strain values include 0.01 %; other methods may be used, but in case of dispute the phase-shift method prevails. 6.5.6.5 Cable strain is monitored mechanically or with sensors with uncertainty not exceeding +/-0.05 %; values not greater than 0.05 % are judged as no obvious strain, and allowed values include 0.05 %.

6.6 Environmental performance and tests. 6.6.1 Temperature attenuation characteristics. 6.6.1.1 The cable shall pass test method F1 of GB/T 7424.2-2008. For loose-structure cables the temperature ranges and allowable additional attenuation relative to 20 degC shall comply with Table 13: grade codes A (-40 degC to +60 degC), B (-30 to +60 degC), C (-20 to +60 degC), D (-5 to +50 degC); B1.1, B1.3 and B6 fibres - grade 0 no obvious additional attenuation, grade 1 <= 0.05, grade 2 <= 0.10, grade 3 <= 0.15 dB/km; A1a and A1b fibres - grade 0 no obvious additional attenuation, grade 1 <= 0.10, grade 2 <= 0.20, grade 3 <= 0.30 dB/km. 6.6.1.2 For tight-structure cables Table 14 applies with the same temperature grades A to D: B1.1, B1.3 and B6 fibres - grade 1 <= 0.30, grade 2 <= 0.40, grade 3 <= 0.50 dB/km; A1a and A1b fibres - grade 1 <= 0.50, grade 2 <= 0.60, grade 3 <= 0.80 dB/km.

6.6.2 Dripping. Filled cables shall pass test method F6 of GB/T 7424.2-2008; at 70 degC there shall be no dripping of filling or coating compound. 6.6.3 Sheath integrity. 6.6.3.1 The plastic sheath shall be continuous and intact; where there is a metal layer beneath it, sheath integrity shall be tested by an electrical method. 6.6.3.2 In the spark test the plastic sheath shall not break down at the voltages of Table 15: DC 9t kV with a maximum of 25 kV; AC 6t kV (r.m.s.) with a maximum of 15 kV, t being the nominal plastic sheath thickness in mm. 6.6.3.3 When required by the user, a water immersion test may be used to check the integrity of aluminium (or steel)-polyethylene bonded sheaths (excluding flame-retardant polyethylene sheaths); after 24 h immersion (Table 16) the insulation resistance to water between metal parts and water (DC 500 V, 1 min) shall be >= 800 MOhm.km for small size premises cables and >= 2 000 MOhm.km for other premises cables, and the dielectric strength shall withstand DC 3 kV and DC 15 kV respectively for 2 min without breakdown. 6.6.4 Water penetration. Where required, and unless otherwise specified, the cable shall pass test method F5B of GB/T 7424.2-2008.

6.6.5 Tests. 6.6.5.1 Unless otherwise specified, environmental performance is verified according to the relevant methods of GB/T 7424.2-2008. 6.6.5.2 The monitoring wavelength is 1 550 nm for B1.1, B1.3 and B6 single-mode fibres and 1 300 nm for A1a.1a, A1a.2a, A1a.3a, A1b and A1a.1b, A1a.2b, A1a.3b multimode fibres. 6.6.5.3 Changes in attenuation coefficient should be measured by the backscattering monitoring method of YD/T 629.2, with uncertainty not exceeding +/-0.02 dB/km for single-mode and +/-0.08 dB/km for multimode fibres; changes within these limits are judged as no obvious change, and allowed changes include this uncertainty.

6.7 Fire performance. 6.7.1 The fire performance of the cable shall meet the requirements of the application environment; flame-retardant cables shall pass the corresponding flame-retardant tests. 6.7.2 Flame-retardant cables shall meet: a) flame retardancy - pass the single vertical burning test of GB/T 18380.12-2008 and, when required by the user, the category C bunched cable test of GB/T 18380.35-2008; b) smoke density - the smoke shall not reduce light transmittance below 50 %; c) corrosivity - the gases produced by combustion shall have a pH of at least 4.3 and a conductivity of at most 10 uS/mm.

6.8 Environmental protection performance. When required by the user, the cable constituent materials shall be classified according to GB/T 26572-2011. In homogeneous materials (EEP-A class) the limits of restricted substances shall comply with Table 17: lead 0.1 %, cadmium 0.01 %, mercury 0.1 % (heavy metals) and hexavalent chromium 0.1 % (listed in the table under organic bromides), as mass fractions; restricted substances in other material classes shall comply with GB/T 26572-2011. 6.9 Other requirements. Requirements other than those of this document are specified in the relevant product standards. 6.10 Installation. When the cable is led indoors, it should be installed in fire-resistant ducts or trays.

Annex A (informative) Classification codes of optical fibre characteristics

A.1 Classification codes. With reference to IEC 60794-3-21:2015, YD/T 926.2-2009 and ISO/IEC 11801-1:2017, the characteristic classification codes correspond to fibre types as follows: OS1 - single-mode fibre B1.1, B1.3 or B6; OS2 - single-mode fibre B1.3 or B6 subcategories a1, a2; OM1 - multimode fibre A1a.1, A1b; OM2 - multimode fibre A1a.1, A1b; OM3 - multimode fibre A1a.2; OM4 - multimode fibre A1a.3.

A.2 Characteristic codes of single-mode fibres (Table A.1, maximum attenuation coefficient at 1 310 / 1 383 / 1 550 nm in dB/km): OS1 - B1.1 0.40 / - / 0.30; B1.3 0.40 / 0.4 / 0.30; B6.a1 0.40 / 0.4 / 0.30; B6.a2 0.40 / 0.4 / 0.30; B6.b2 0.6 / - / 0.4; B6.b3 0.6 / - / 0.4. OS2 - B1.3, B6.a1 and B6.a2 0.40 / 0.40 / 0.30.

A.3 Characteristic codes of multimode fibres (Tables A.2 and A.3). Nominal core diameter 50.0 um for A1a types and 62.5 um for A1b. Maximum attenuation at 850 nm / 1 300 nm: OM1 (A1a.1, A1b) 3.5 / 1.5 dB/km; OM2 (A1a.1, A1b) 3.5 / 1.5; OM3 (A1a.2) 2.5 / 0.8; OM4 (A1a.3) 2.5 / 0.8. Minimum bandwidth (overfilled launch 850 nm / overfilled launch 1 300 nm / effective modal bandwidth 850 nm, MHz.km): OM1 >= 200 / >= 500 / not applicable; OM2 >= 500 / >= 500 / not applicable; OM3 >= 1 500 / >= 500 / >= 2 000; OM4 >= 3 500 / >= 500 / >= 4 700.

Annex B (informative) Dynamic friction coefficient of optical fibre cables

This test method applies to the dynamic friction coefficient test of premises cables for duct application. The test set-up is shown in Figure B.1, which shows a test sample lying between two layers of four fixed samples, one layer on the test platform and one under a stainless steel plate loaded by a normal force.

Procedure: a) from the same cable reel take 8 lengths of (150 +/- 1) mm as fixed samples to be fixed on the test platform and the stainless steel plate, and 5 lengths not exceeding 3 000 mm as test samples; b) fix 4 of the 150 mm fixed samples side by side and tightly together on the test platform and 4 on a stainless steel plate of length (150 +/- 1) mm; c) place a test sample on the fixed samples along the axis of the cables fixed on the platform, and lightly press the stainless steel plate carrying the other 4 fixed samples onto the test sample, with the cable end faces on the plate aligned with those on the platform; d) apply a pressure of 20 N to the test cable through the stainless steel plate; e) pull the test sample at a uniform speed of (500 +/- 10) mm/min, measure the pulling force with a force gauge of suitable accuracy, and take the maximum force measured during uniform movement as the pulling force of the sample; f) after testing the 5 samples, calculate their average pulling force; g) dynamic friction coefficient = average pulling force of the 5 samples (N) / (2 x 20) (N).

Note: for non-circular cables, the fixed samples are fixed with their minor axis in contact with the test platform and stainless steel plate, and the test sample likewise contacts the fixed samples with its minor axis.

Bibliography

[1] YD/T 926.2-2009 Generic cabling system for building telecommunications - Part 2: Technical requirements for cables and optical fibre cables.

[2] ISO/IEC 11801-1:2017 Information technology - Generic cabling for customer premises - Part 1: General requirements.

[3] IEC 60794-3-21:2015 Optical fibre cables - Part 3-21: Outdoor cables - Product specification for optical self-supporting aerial telecommunication cables for use in premises cabling (Edition 2.0).