SIST EN 60794-2-20:2014

Optical fibre cables - Part 2-20: Indoor cables - Family specification for multi-fibre optical cables

EN IEC 60794-2-20 is a family specification covering multi-fibre optical cables for indoor use. The requirements of the sectional specification IEC 60794-2 are applicable to cables covered by this standard. Annex B contains a Blank Detail Specification and general guidance in case the cables are intended to be used in installation governed by the MICE table of ISO/IEC 24702 (Industrial premises).

Lichtwellenleiterkabel - Teil 2-20: LWL-Innenkabel - Familienspezifikation für Mehrfaser-Lichtwellenleiterkabel

Optical fibre cables -- Part 2-20: Indoor cables - Family specification for multi-fibre optical cables

La CEI 60794-2-20:2013 est une spécification de famille qui couvre les câbles optiques multifibres pour utilisation intérieure. Les exigences de la spécification intermédiaire CEI 60794-2 sont applicables aux câbles couverts par la présente norme. L'Annexe B contient une Spécification Particulière Cadre et des lignes directrices générales dans le cas où les câbles sont destinés à être utilisés dans une installation relevant du tableau MICE de la norme ISO/CEI 24702 (locaux industriels). Cette troisième édition annule et remplace la deuxième édition publiée en 2008. Elle constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:  - la suppression de l'Annexe C;  - la référence aux normes de fibres les plus récentes;  - la référence à la nouvelle série CEI 60794-1-2X. La présente norme doit être utilisée conjointement avec la CEI 60794-1-1, la CEI 60794-1-2 et la CEI 60794-2. Mots clés: spécification de famille qui couvre les câbles optiques multifibres pour utilisation intérieure

Optični kabli - 2-20. del: Optični kabli za notranjo uporabo - Rodovna specifikacija za distribucijske kable z več optičnimi vlakni

Standard EN IEC 60794-2-20 je skupinska specifikacija, ki zajema distribucijske kable z več optičnimi vlakni za notranjo uporabo. Zahteve področne specifikacije IEC 60794-2 se uporabljajo za kable, ki jih zajema ta standard. Dodatek B vsebuje okvirno podrobno specifikacijo in splošna navodila za kable, ki so namenjeni uporabi v napeljavi, ki jo določa tabela MICE iz standarda ISO/IEC 24702 (Industrijska okolja).

General Information

• Status: Published
• Publication Date: 08-Jul-2014
• ICS: 33.180.10 - Fibres and cables
• Technical Committee: MOC - Mobile Communications
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 16-Jun-2014
• Due Date: 21-Aug-2014
• Completion Date: 09-Jul-2014
• Ref Project: EN 60794-2-20:2014 - Optical fibre cables - Part 2-20: Indoor cables - Family specification for multi-fibre optical cables

Relations

• Revised: SIST EN 60794-2-20:2010 - Optical fibre cables - Part 2-20: Indoor optical fibre cables - Family specification for multi-fibre optical distribution cables (IEC 60794-2-20:2008)
• Effective Date: 17-May-2013
• Replaces: SIST EN 60794-2-20:2010 - Optical fibre cables - Part 2-20: Indoor optical fibre cables - Family specification for multi-fibre optical distribution cables (IEC 60794-2-20:2008)
• Effective Date: 28-Jan-2023
• Revised: oSIST prEN IEC 60794-2-20:2023 - Optical fibre cables - Part 2-20: Indoor cables - Family specification for multi-fibre optical cables
• Effective Date: 23-Jan-2023
• Revised: oSIST prEN IEC 60794-2-20:2023 - Optical fibre cables - Part 2-20: Indoor cables - Family specification for multi-fibre optical cables
• Effective Date: 26-Apr-2022
• Replaces: SIST EN 60794-2-20:2010 - Optical fibre cables - Part 2-20: Indoor optical fibre cables - Family specification for multi-fibre optical distribution cables (IEC 60794-2-20:2008)
• Effective Date: 07-Jun-2022

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN 60794-2-20:2014
01-september-2014
2SWLþQLNDEOLGHO2SWLþQLNDEOL]DQRWUDQMRXSRUDER5RGRYQDVSHFLILNDFLMD
]DGLVWULEXFLMVNHNDEOH]YHþRSWLþQLPLYODNQL
Optical fibre cables - Part 2-20: Indoor cables - Family specification for multi-fibre optical
cables
Lichtwellenleiterkabel - Teil 2-20: LWL-Innenkabel - Familienspezifikation für Mehrfaser-
Lichtwellenleiterkabel
Optical fibre cables -- Part 2-20: Indoor cables - Family specification for multi-fibre optical
cables
Ta slovenski standard je istoveten z: EN 60794-2-20:2014
ICS:
33.180.10 2SWLþQDYODNQDLQNDEOL Fibres and cables
SIST EN 60794-2-20:2014 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 60794-2-20:2014

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SIST EN 60794-2-20:2014


EUROPEAN STANDARD EN 60794-2-20

NORME EUROPÉENNE

EUROPÄISCHE NORM
May 2014
ICS 33.180.01 Supersedes EN 60794-2-20:2010
English Version
Optical fibre cables - Part 2-20: Indoor cables - Family
specification for multi-fibre optical cables
(IEC 60794-2-20:2013)
Optical fibre cables - Part 2-20: Indoor cables - Family Lichtwellenleiterkabel - Teil 2-20: LWL-Innenkabel -
specification for multi-fibre optical cables Familienspezifikation für Mehrfaser-Lichtwellenleiterkabel
(CEI 60794-2-20:2013) (IEC 60794-2-20:2013)
This European Standard was approved by CENELEC on 2013-12-10. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.



European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2014 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
 Ref. No. EN 60794-2-20:2014 E

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SIST EN 60794-2-20:2014
EN 60794-2-20:2014 - 2 -
Foreword
The text of document 86A/1513/FDIS, future edition 3 of IEC 60794-2-20, prepared by SC 86A, "Fibres
and cables", of IEC TC 86, "Fibre optics" was submitted to the IEC-CENELEC parallel vote and approved
by CENELEC as EN 60794-2-20:2014.
The following dates are fixed:
(dop) 2014-11-16
• latest date by which the document has
to be implemented at national level by
publication of an identical national
standard or by endorsement
• latest date by which the national (dow) 2016-12-10
standards conflicting with the
document have to be withdrawn

This document supersedes EN 60794-2-20:2010.
EN 60794-2-20:2014 includes the following significant technical changes with respect to EN 60794-2-
20:2010:

• removal of Annex C;
• reference to the most recent fibre standards;
• reference to the new series EN 60794-1-2X.
This standard is to be used in conjunction with IEC 60794-1-1, IEC 60794-1-2 and IEC 60794-2.

Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such patent
rights.
Endorsement notice
The text of the International Standard IEC 60794-2-20:2013 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:
IEC 60654 (Series) NOTE  Harmonized as EN 60654 (Series) (not modified).
IEC 60721-1 NOTE  Harmonized as EN 60721-1 (not modified).
IEC 60721-3-3 NOTE  Harmonized as EN 60721-3-3 (not modified).
IEC 61000-6-2 NOTE  Harmonized as EN 61000-6-2 (not modified).
IEC 61326 (Series) NOTE  Harmonized as EN 61326 (Series) (not modified).
IEC 61918 NOTE  Harmonized as EN 61918 (modified).

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SIST EN 60794-2-20:2014
- 3 - EN 60794-2-20:2014

Annex ZA
(normative)

Normative references to international publications
with their corresponding European publications

The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.

NOTE  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.

To be used together with the Annexes ZA of EN 60794-1-1 and EN 60794-1-2.
Publication Year Title EN/HD Year

IEC 60189-1 Low-frequency cables and wires with PVC - -
insulation and PVC sheath -
Part 1: General test and measuring methods


IEC 60304 Standard colours for insulation for low- HD 402 S2
frequency cables and wires


IEC 60793-1-20 Optical fibres - EN 60793-1-20
Part 1-20: Measurement methods and test
procedures - Fibre geometry


IEC 60793-1-21 Optical fibres - EN 60793-1-21
Part 1-21: Measurement methods and test
procedures - Coating geometry


IEC 60793-2-10 Optical fibres - EN 60793-2-10
Part 2-10: Product specifications - Sectional
specification for category A1 multimode fibres


IEC 60793-2-50 Optical fibres - EN 60793-2-50
+ corr. January Part 2-50: Product specifications - Sectional
specification for class B single-mode fibres


IEC 60794-1-1 Optical fibre cables - EN 60794-1-1
+ corr. January Part 1-1: Generic specification - General

IEC 60794-1-2 Optical fibre cables - Part 1-2: Generic EN 60794-1-2
specification - Cross reference table for optical
cable test procedures


IEC 60794-1-20 Optical fibre cables - FprEN 60794-1-20
Part 1-20: Generic specification - Basic optical
cable test procedures - General and
Definitions


IEC 60794-1-22 Optical fibre cables - EN 60794-1-22
Part 1-22: Generic specification - Basic optical
cable test procedures - Environmental test
methods


IEC 60794-1-23 Optical fibre cables - EN 60794-1-23
Part 1-23: Generic specification - Basic optical
cable test procedures - Cable element test
methods


IEC 60794-2 2002 Optical fibre cables - EN 60794-2 2003
Part 2: Indoor cables - Sectional specification


IEC 60794-3 2001 Optical fibre cables - EN 60794-3 2002
Part 3: Sectional specification - Outdoor
cables

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SIST EN 60794-2-20:2014
EN 60794-2-20:2014 - 4 -
IEC 60811-202 Electric and optical fibre cables - Test EN 60811-202
methods for non-metallic materials -
Part 202: General tests - Measurement of
thickness of non-metallic sheath


IEC 60811-203 Electric and optical fibre cables - Test EN 60811-203
methods for non-metallic materials -
Part 203: General tests - Measurement of
overall dimensions


IEC 60811-504 Electric and optical fibre cables - Test EN 60811-504
methods for non-metallic materials -
Part 504: Mechanical tests - Bending tests at
low temperature for insulation and sheaths


IEC/TR 62222 Fire performance of communication cables - -
installed in buildings

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SIST EN 60794-2-20:2014




IEC 60794-2-20

®


Edition 3.0 2013-11




INTERNATIONAL



STANDARD




NORME



INTERNATIONALE
colour

inside










Optical fibre cables –

Part 2-20: Indoor cables – Family specification for multi-fibre optical cables




Câbles à fibres optiques –

Partie 2-20: Câbles intérieurs – Spécification de famille pour les câbles optiques

multifibres















INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE

PRICE CODE
INTERNATIONALE

CODE PRIX S


ICS 33.180.01 ISBN 978-2-8322-1166-3



Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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SIST EN 60794-2-20:2014
– 2 – 60794-2-20 © IEC:2013
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Construction . 7
3.1 General . 7
3.2 Optical fibres . 7
3.3 Buffer . 7
3.4 Ruggedized fibre . 8
3.5 Slotted core . 8
3.6 Tube . 8
3.7 Stranded tube . 8
3.8 Ribbon structure . 8
3.9 Strength and anti-buckling members. 8
3.10 Ripcord . 8
3.11 Sheath . 8
3.12 Sheath marking . 9
3.13 Identification . 9
3.14 Examples of cable constructions . 9
4 Tests . 9
4.1 General . 9
4.2 Dimensions . 9
4.3 Mechanical requirements . 9
4.3.1 Cable tensile performance . 9
4.3.2 Cable crush . 10
4.3.3 Cable impact . 10
4.3.4 Cable bending . 10
4.3.5 Cable repeated bending. 10
4.3.6 Cable bending under tension . 10
4.3.7 Cable bending at low temperature . 11
4.3.8 Cable flexing . 11
4.3.9 Cable torsion . 11
4.3.10 Cable kink . 11
4.4 Environmental requirements – Temperature cycling. 11
4.5 Transmission requirements. 12
4.6 Fire performance . 12
Annex A (informative) Examples of cable constructions . 13
Annex B (informative) Family specification for multi-fibre optical cables – Blank detail
specification and minimum requirements . 17
Bibliography . 22

Figure A.1 – Example of cross-section of a 12 fibre cable . 13
Figure A.2 – Example of cross-section of a 36 fibre cable . 13
Figure A.3 – Example of cross-section of a 6 fibre break-out cable . 14
Figure A.4 – Example of cross-section of a 24 fibre break-out cable . 14
Figure A.5 – Example of cross-section of a slotted core type indoor cable with 4 fibre
ribbons . 15

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SIST EN 60794-2-20:2014
60794-2-20 © IEC:2013 – 3 –
Figure A.6 – Example of cross-section of an SZ (reverse oscillating lay) slotted core
type indoor cable with 2 fibre ribbons . 15
Figure A.7 – Example of cross-section of an SZ (reverse oscillating lay) slotted core
type indoor cable with 4 fibre bundles . 16
Figure A.8 – Example of multi-fibre unitube cable . 16
Figure A.9 – Example of multi-fibre cable . 16

Table 1 – Dimensions of buffered fibres . 8
Table 2 – Sample temperature cycling values . 12
Table B.1 – Cable description (1 of 2) . 17
Table B.2 – Cable element . 18
Table B.3 – Cable construction . 19
Table B.4 – Installation and operating conditions . 20
Table B.5 – Tests applicable . 20

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SIST EN 60794-2-20:2014
– 4 – 60794-2-20 © IEC:2013
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

OPTICAL FIBRE CABLES –

Part 2-20: Indoor cables –
Family specification for multi-fibre optical cables

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60794-2-20 has been prepared by sub-committee 86A: Fibres and
cables, of IEC technical committee 86: Fibre optics.
This third edition cancels and replaces the second edition published in 2008 and constitutes a
technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
– removal of Annex C;
– reference to the most recent fibre standards;
– reference to the new series IEC 60794-1-2X.
This standard is to be used in conjunction with IEC 60794-1-1, IEC 60794-1-2 and
IEC 60794-2.

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SIST EN 60794-2-20:2014
60794-2-20 © IEC:2013 – 5 –
The text of this standard is based on the following documents:
FDIS Report on voting
86A/1513/FDIS 86A/1549/RVD

Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of IEC 60794 series, published under the general title Optical fibre cables,
can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.

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SIST EN 60794-2-20:2014
– 6 – 60794-2-20 © IEC:2013
OPTICAL FIBRE CABLES –

Part 2-20: Indoor cables –
Family specification for multi-fibre optical cables



1 Scope
This part of IEC 60794 is a family specification covering multi-fibre optical cables for indoor
use. The requirements of the sectional specification IEC 60794-2 are applicable to cables
covered by this standard. Annex B contains a Blank Detail Specification and general guidance
in case the cables are intended to be used in installation governed by the MICE table of
1
ISO/IEC 24702 (Industrial premises) [11] .
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
NOTE These reference complete the normative references already listed in the generic specification
(IEC 60794-1-1 and IEC 60794-1-2).
IEC 60189-1, Low-frequency cables and wires with PVC insulation and PVC sheath – Part 1:
General test and measuring methods
IEC 60304, Standard colours for insulation for low-frequency cables and wires
IEC 60793-1-20, Optical fibres – Part 1-20: Measurement methods and test procedures –
Fibre geometry
IEC 60793-1-21, Optical fibres – Part 1-21: Measurement methods and test procedures –
Coating geometry
IEC 60793-2-10, Optical fibres – Part 2-10: Product specifications – Sectional specification for
category A1 multimode fibres
IEC 60793-2-50, Optical fibres – Part 2-50: Product specifications – Sectional specification for
class B single-mode fibres
IEC 60794-1-1, Optical fibre cables – Part 1-1: Generic specification – General
IEC 60794-1-2, Optical fibre cables – Part 1-2: Generic specification – Basic optical cable test
procedures
IEC 60794-1-20, Optical fibre cables – Part 1-20: Generic specification – Basic optical cable
2
test procedures – General and definitions
___________
1
 Figures in square brackets refer to the Bibliography.
2 To be published.

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SIST EN 60794-2-20:2014
60794-2-20 © IEC:2013 – 7 –
IEC 60794-1-22, Optical fibre cables – Part 1-22: Generic specification – Basic optical cable
test procedures – Environmental test methods
IEC 60794-1-23, Optical fibre cables – Part 1-23: Generic specification – Basic optical cable
test procedures – Cable element test methods
IEC 60794-2:2002, Optical fibre cables – Part 2: Indoor cables – Sectional specification
IEC 60794-3:2001, Optical fibre cables – Part 3: Sectional specification – Outdoor cables
IEC 60811-202, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 202: General tests – Measurement of thickness of non-metallic sheath
IEC 60811-203, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 203: General tests – Measurement of overall dimensions.
IEC 60811-504, Electric and optical fibre cables – Test methods for non-metallic materials –
Part 504: Mechanical tests – Bending tests at low temperature for insulation and sheaths
IEC/TR 62222, Fire performance of communication cables installed in buildings
3 Construction
3.1 General
In addition to the constructional requirements in IEC 60794-2, the following considerations
apply to multi-fibre indoor cables.
The cable shall be designed and manufactured for an expected operating lifetime of at least
15 years. In this context, the attenuation at the operational wavelength(s) of the optical fibres
contained in the installed cable shall not exceed values agreed between customer and
supplier. The materials in the cable shall not present a health or environmental hazard within
its intended use.
There shall be no fibre splice in a delivery length unless otherwise agreed by customer and
supplier.
It shall be possible to identify each individual fibre throughout the length of the cable.
3.2 Optical fibres
Class A1 multimode fibres which meet the requirements of IEC 60793-2-10 or class B sub-
categories B1.1, B1.3, B6_a, and B6_b single-mode optical fibres which meet the
requirements of IEC 60793-2-50 shall be used. The linear coefficient of optical fibre
attenuation and attenuation point discontinuity may be affected by the cable manufacturing
process. Maximum values for these optical characteristics shall be agreed between customer
and supplier.
3.3 Buffer
If a tight or semi-tight (loosely applied) buffer is required, it shall consist of one or more layers
of inert material. The buffer shall be easily removable. For tight buffers, the buffer and fibre
primary coating shall be removable in one operation over a length of 15 mm to 25 mm,
depending on customer requirements. For semi-tight buffers, the buffer shall be easily
removable over a length of 0,3 m to 2,0 m.
Buffer dimensions are shown in Table 1.

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SIST EN 60794-2-20:2014
– 8 – 60794-2-20 © IEC:2013
Table 1 – Dimensions of buffered fibres
Buffer type Nominal diameter Tolerances
mm mm
Semi-tight buffer 0,3 to 1,4 ± 0,05
Tight buffer 0,3 to 1,0
± 0,05

3.4 Ruggedized fibre
Further protection can be provided to tight or semi-tight buffered fibres by surrounding them
with non-metallic strength members within a sheath of suitable material.
3.5 Slotted core
The slotted core is obtained by extruding a suitable material with a defined number of slots,
providing helical or SZ (reverse-oscillating lay) configuration along the core. One or more
primary coated fibres or optical elements such as ribbons or fibre bundles are located in each
slot.
3.6 Tube
One or more primary coated or buffered fibres or ribbons are packaged (loosely or not) in a
tube construction which may be filled. The tube may be reinforced with a composite wall.
3.7 Stranded tube
Multiple tubes, containing one or more primary coated or buffered fibres or ribbons, are
stranded around a central member. For the sake of preserving cable geometry, some tubes
may be "filler" or "empty" elements not containing optical fibres.
3.8 Ribbon structure
Ribbon structures shall conform to 6.5 and 8.2.3 of IEC 60794-3:2001. Fibres shall be
arranged to be parallel and formed into ribbons so that the fibres remain parallel and do not
cross over. Unless otherwise specified, each ribbon shall be uniquely identified with a printed
legend or by uniquely colouring the reference fibre and/or by colouring the matrix material of
the ribbon.
3.9 Strength and anti-buckling members
The cable shall be designed with sufficient strength members to meet installation and service
conditions so that the fibres are not subjected to strain in excess of limits agreed between
customer and supplier.
The strength and/or anti-buckling members may be either metallic or non-metallic and may be
located in the cable core and/or under the sheath and/or in the sheath.
3.10 Ripcord
If required, a ripcord may be provided beneath the sheath.
3.11 Sheath
The cable shall have an overall protective sheath. The cable diameter shall be specified in the
relevant blank detail specification (or product) specification.

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SIST EN 60794-2-20:2014
60794-2-20 © IEC:2013 – 9 –
3.12 Sheath marking
If required, the cable shall be marked as agreed between customer and supplier.
3.13 Identification
Optical fibres, buffers and sub-unit sheaths shall be easily and uniquely identifiable through
the use of a suitable colour code (i.e. IEC 60304) and/or an easily visible numbering scheme
to be agreed between customer and supplier.
3.14 Examples of cable constructions
Examples of some main types of cable construction are shown in Annex A. Other
configurations (e.g. multi-layer constructions) are not precluded if they meet the mechanical,
environmental and transmis
...