IEC 60794-2-20:2008

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

IEC 60794-2-20:2008 is a family specification covering multi-fibre optical distribution cables for indoor use. The requirements of the sectional specification IEC 60794-2 are applicable to cables covered by this standard. The main changes from the previous edition include:
- cable crush to be measured both during and after load;
- cable torsion test length parameter correlated to cable outer diameter;
- cable description and construction blank detail specification annexes;
- MICE environment blank detail specification is addressed in Annex B.
This publication is to be read in conjunction with  IEC 60794-1-1:2001, IEC 60794-1-2:2003 and IEC 60794-2:2002.

Câbles à fibres optiques - Partie 2-20: Câbles intérieurs - Spécification de famille pour les câbles de distribution optiques multifibres

La CEI 60794-2-20:2008 est une spécification de famille qui couvre les câbles de distribution optiques multifibres pour usage intérieur. Les exigences de la spécification intermédiaire CEI 60794-2 sont applicables aux câbles couverts par la présente norme. Les principales modifications par rapport à l'édition précédente concernent:
- l'écrasement du câble à mesurer à la fois pendant et après application de la charge;
- le paramètre de longueur d'essai de torsion de câble par rapport au diamètre extérieur du câble;
- les annexes concernant la description du câble et la spécification particulière cadre de construction;
- la spécification particulière cadre de l'environnement MICE est traitée à l'Annexe B.
Cette publication doit être lue conjointement avec la CEI 60794-1-1:2001, la CEI 60794-1-2:2003 et la CEI 60794-2:2002.

General Information

• Status: Published
• Publication Date: 04-Nov-2008
• ICS: 33.180.01 - Fibre optic systems in general
• Technical Committee: SC 86A - Fibres and cables
• Current Stage: DELPUB - Deleted Publication
• Completion Date: 05-Nov-2013

Relations

• Revised: IEC 60794-2-20:2013 - Optical fibre cables - Part 2-20: Indoor cables - Family specification for multi-fibre optical cables
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 60794-2-20
Edition 2.0 2008-11
INTERNATIONAL
STANDARD


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



IEC 60794-2-20:2008(E)

---------------------- Page: 1 ----------------------
THIS PUBLICATION IS COPYRIGHT PROTECTED
Copyright © 2008 IEC, Geneva, Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester.
If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,
please contact the address below or your local IEC member National Committee for further information.

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CH-1211 Geneva 20
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Email: [e-mail]
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About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.
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Vocabulary online.
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ed f
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---------------------- Page: 2 ----------------------
IEC 60794-2-20
Edition 2.0 2008-11
INTERNATIONAL
STANDARD


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


INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
T
ICS 33.180.01 ISBN 978-2-88910-291-4
® Registered trademark of the International Electrotechnical Commission

---------------------- Page: 3 ----------------------
– 2 – 60794-2-20 © IEC:2008(E)
CONTENTS
FOREWORD.4
1 Scope.6
2 Normative references .6
3 Construction .6
3.1 General .6
3.2 Optical fibres and primary coating .7
3.3 Buffer .7
3.4 Ruggedised fibre .7
3.5 Slotted core.7
3.6 Tube.7
3.7 Stranded tube.7
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 .8
3.13 Identification.8
3.14 Examples of cable constructions .8
4 Tests .8
4.1 Dimensions .8
4.2 Mechanical requirements.9
4.2.1 Cable tensile performance .9
4.2.2 Cable crush .9
4.2.3 Cable impact .9
4.2.4 Cable bending .10
4.2.5 Cable repeated bending .10
4.2.6 Cable bending under tension .10
4.2.7 Cable bending at low temperature .10
4.2.8 Cable flexing .10
4.2.9 Cable torsion .10
4.2.10 Cable kink .11
4.3 Environmental requirements – Temperature cycling .11
4.4 Transmission requirements .11
4.5 Fire performance.11
Annex A (informative) Examples of cable constructions .13
Annex B (informative) Family specification for multi-fibre optical distribution cables –
Blank detail specification and minimum requirements .18
Bibliography.24

Figure A.1 – Example of cross-section of a 12 fibre distribution cable.13
Figure A.2 – Example of cross-section of a 36 fibre distribution 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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60794-2-20 © IEC:2008(E) – 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.17

Table 1 – Dimensions of buffered fibres.7
Table 2 – Sample temperature cycling values .11
Table B.1 – Cable description .18
Table B.2 – Cable element.19
Table B.3 – Cable construction .20
Table B.4 – Installation and operating conditions .20
Table B.5 – Tests applicable.21
Table B.6 – Specifications for industrial premises installations as defined in
ISO/IEC 24702.22

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– 4 – 60794-2-20 © IEC:2008(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________

OPTICAL FIBRE CABLES –

Part 2-20: Indoor cables –
Family specification for multi-fibre optical distribution 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 provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
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 subcommittee 86A: Fibres and
cables, of IEC technical committee 86: Fibre optics.
This second edition cancels and replaces the first edition published in 2003. It constitutes a
technical revision.
The main changes from the previous edition include:
– cable crush to be measured both during and after load;
– cable torsion test length parameter correlated to cable outer diameter;
– cable description and construction blank detail specification annexes;
– MICE environment blank detail specification is addressed in Annex B.
This standard is to be used in conjunction with IEC 60794-1-1 and IEC 60794-1-2, and
IEC 60794-2.

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60794-2-20 © IEC:2008(E) – 5 –
The text of this standard is based on the following documents:
CDV Report on voting
86A/1187/CDV 86A/1221/RVC

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 maintenance result 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.
A bilingual version of this publication may be issued at a later date.

---------------------- Page: 7 ----------------------
– 6 – 60794-2-20 © IEC:2008(E)
OPTICAL FIBRE CABLES –

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



1 Scope
This part of IEC 60794 is a family specification covering multi-fibre optical distribution cables
for indoor use. The requirements of the sectional specification IEC 60794-2 are applicable to
cables covered by this standard.
Annex B contains requirements that supersede the normal requirements in case the cables
are intended to be used in installation governed by the MICE table of ISO/IEC 24702 (i.e.
Industrial premises).
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
They complete the normative references already listed in the generic specification
(IEC 60794-1-1, Clause 2, and IEC 60794-1-2, Clause 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 60793-2-10, 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 60794-2, Optical fibre cables – Part 2: Indoor cables – Sectional specification
IEC 60811-1-4, Common test methods for insulating and sheathing materials of electric
cables – Part 1: Methods for general application – Section four: Tests at low temperature
IEC 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

---------------------- Page: 8 ----------------------
60794-2-20 © IEC:2008(E) – 7 –
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 and primary coating
A1 multimode fibres which meet the requirements of IEC 60793-2-10 or 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.
Table 1 – Dimensions of buffered fibres
Buffer type Nominal diameter Tolerances
mm mm
Semi-tight buffer 0,3 - 1,3
±0,05
Tight buffer 0,3 - 1,0
±0,05

3.4 Ruggedised fibre
Further protection can be provided to tight or semi-tight secondary coated 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.

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– 8 – 60794-2-20 © IEC:2008(E)
3.8 Ribbon structure
Ribbon structures shall conform to IEC 60794-3, 6.5 and 8.2.3. 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.
3.12 Sheath marking
If required, the cable shall be marked as agreed between the customer and the supplier.
3.13 Identification
Optical fibres, secondary coatings 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 the customer and the 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-
...

IEC 60794-2-20
®

Edition 2.0 2008-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside


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

Câbles à fibres optiques –
Partie 2-20: Câbles intérieurs – Spécification de famille pour les câbles de
distribution optiques multifibres

IEC 60794-2-20:2008

---------------------- Page: 1 ----------------------
THIS PUBLICATION IS COPYRIGHT PROTECTED
Copyright © 2008 IEC, Geneva, Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by
any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either IEC or
IEC's member National Committee in the country of the requester.
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Email: [e-mail]
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About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.
 Catalogue of IEC publications: www.iec.ch/searchpub
The IEC on-line Catalogue enables you to search by a variety of criteria (reference number, text, technical committee,…).
It also gives information on projects, withdrawn and replaced publications.
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in English and French, with equivalent terms in additional languages. Also known as the International Electrotechnical
Vocabulary online.
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---------------------- Page: 2 ----------------------
IEC 60794-2-20
®

Edition 2.0 2008-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside


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

Câbles à fibres optiques –
Partie 2-20: Câbles intérieurs – Spécification de famille pour les câbles de
distribution optiques multifibres


INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX T
ICS 33.180.01 ISBN 978-2-88912-615-6

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

---------------------- Page: 3 ----------------------
– 2 – 60794-2-20  IEC:2008

CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Construction . 6
3.1 General . 6
3.2 Optical fibres and primary coating . 7
3.3 Buffer . 7
3.4 Ruggedised fibre . 7
3.5 Slotted core . 7
3.6 Tube. 7
3.7 Stranded tube. 7
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 . 8
3.13 Identification. 8
3.14 Examples of cable constructions . 8
4 Tests . 8
4.1 Dimensions . 8
4.2 Mechanical requirements . 9
4.2.1 Cable tensile performance . 9
4.2.2 Cable crush . 9
4.2.3 Cable impact . 9
4.2.4 Cable bending . 10
4.2.5 Cable repeated bending . 10
4.2.6 Cable bending under tension . 10
4.2.7 Cable bending at low temperature . 10
4.2.8 Cable flexing . 10
4.2.9 Cable torsion . 10
4.2.10 Cable kink . 11
4.3 Environmental requirements – Temperature cycling . 11
4.4 Transmission requirements . 11
4.5 Fire performance . 11
Annex A (informative) Examples of cable constructions . 13
Annex B (informative) Family specification for multi-fibre optical distribution cables –
Blank detail specification and minimum requirements . 18
Bibliography . 24

Figure A.1 – Example of cross-section of a 12 fibre distribution cable . 13
Figure A.2 – Example of cross-section of a 36 fibre distribution 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

---------------------- Page: 4 ----------------------
60794-2-20  IEC:2008 – 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 . 17

Table 1 – Dimensions of buffered fibres . 7
Table 2 – Sample temperature cycling values . 11
Table B.1 – Cable description . 18
Table B.2 – Cable element . 19
Table B.3 – Cable construction . 20
Table B.4 – Installation and operating conditions . 20
Table B.5 – Tests applicable . 21
Table B.6 – Specifications for industrial premises installations as defined in
ISO/IEC 24702 . 22

---------------------- Page: 5 ----------------------
– 4 – 60794-2-20  IEC:2008
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________

OPTICAL FIBRE CABLES –

Part 2-20: Indoor cables –
Family specification for multi-fibre optical distribution 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 subcommittee 86A: Fibres and
cables, of IEC technical committee 86: Fibre optics.
This second edition cancels and replaces the first edition published in 2003. It constitutes a
technical revision.
The main changes from the previous edition include:
– cable crush to be measured both during and after load;
– cable torsion test length parameter correlated to cable outer diameter;
– cable description and construction blank detail specification annexes;
– MICE environment blank detail specification is addressed in Annex B.
This standard is to be used in conjunction with IEC 60794-1-1 and IEC 60794-1-2, and
IEC 60794-2.

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60794-2-20  IEC:2008 – 5 –
This bilingual version, published in 2011-07, corresponds to the English version.
The text of this standard is based on the following documents:
CDV Report on voting
86A/1187/CDV 86A/1221/RVC

Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
The French version of this standard has not been voted upon.
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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– 6 – 60794-2-20  IEC:2008
OPTICAL FIBRE CABLES –

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



1 Scope
This part of IEC 60794 is a family specification covering multi-fibre optical distribution cables
for indoor use. The requirements of the sectional specification IEC 60794-2 are applicable to
cables covered by this standard.
Annex B contains requirements that supersede the normal requirements in case the cables
are intended to be used in installation governed by the MICE table of ISO/IEC 24702 (i.e.
industrial premises).
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
They complete the normative references already listed in the generic specification
(IEC 60794-1-1, Clause 2, and IEC 60794-1-2, Clause 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 60793-2-10, 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 60794-2, Optical fibre cables – Part 2: Indoor cables – Sectional specification
IEC 60811-1-4, Common test methods for insulating and sheathing materials of electric
cables – Part 1: Methods for general application – Section four: Tests at low temperature
IEC 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

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60794-2-20  IEC:2008 – 7 –
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 and primary coating
A1 multimode fibres which meet the requirements of IEC 60793-2-10 or 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.
Table 1 – Dimensions of buffered fibres
Buffer type Nominal diameter Tolerances
mm mm
Semi-tight buffer 0,3 - 1,3
±0,05
Tight buffer 0,3 - 1,0
±0,05

3.4 Ruggedised fibre
Further protection can be provided to tight or semi-tight secondary coated 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.

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– 8 – 60794-2-20  IEC:2008
3.8 Ribbon structure
Ribbon structures shall conform to IEC 60794-3, 6.5 and 8.2.3. 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.
3.12 Sheath marking
If required, the cable shall be marked as agreed between the customer and the supplier.
3.13 Identification
Optical fibres, secondary coatings 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 the customer and the 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 transmission requirements given in this specification.
4 Tests
Compliance with relevant detail specification requirements shall be verified by carrying out
tests selected from the following subclauses. It is not intended that all tests be carried out; the
frequency of testing shall be agreed between the customer and the supplier.
Unless otherwise specified, all tests shall be carried out at ambient temperature. Attenuation
measurements shall be conducted at the highest specified wavelength.
4.1 Dimensions
The fibre dimensions and tolerances shall be verified in accordance with test method
IEC 60793-1-20, method C or IEC 60793-1-21. The diameter of the buffer and of the cable, as
well as the thickness of the sheath, shall be measured in accordance with the methods of
IEC 60189-1.

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60794-2-20  IEC:2008 – 9 –
4.2 Mechanical requirements
Some of the following tests can be performed on a short sample length of cable which is still
an integral part of a longer length. Thus it becomes possible to detect permanent changes in
attenuation within the measurement uncertainty of the equipment used (see 3.8.2,
Assessment of uncertainties in IEC 60794-1-2). The wavelength and maximum value of this
attenuation change shall be agreed between the customer and the supplier.
4.2.1 Cable tensile performance
Method: IEC 60794-1-2-E1A and/or E1B
Diameter of chuck drums
and transfer devices: not smaller than the minimum bending diameter specified
for the cable under load
Velocity of transfer device: either 100 mm/min or 100 N/min
Load and duration: 400 N or the weight of 1 km of cable, whichever is greater,
and for a minimum period of 5 min
Length of sample: sufficient to achieve the desired accuracy of measurement
of attenuation change (typically 300 m) and shall be
agreed between the customer and the supplier
Requirements: for E1A there shall be no change in attenuation after the
test,
for E1B allowed fibre strain to be agreed between supplier
and customer.
There shall be no visible damage to the cable elements
NOTE 1 Fibre strain above 60 % of the proof test of the all-glass fibre while under test load is not recommended.
NOTE 2 For certain applications specifying MICE classification of ISO/IEC 24702 and related standards, different
load and duration values may be agreed between the customer and the supplier.
4.2.2 Cable crush
Method: IEC 60794-1-2-E3
Force during installation: 500 N
Duration during installation: 1 min
Force during operation: ffs
Duration during operation: ffs
Length between test locations: 500 mm
Requirements: no change in attenuation during the operational test and
after the installation test. There shall be no visible damage
to the cable elements
NOTE For certain applications specifying MICE classification of ISO/IEC 24702 and related standards, different
force values may be agreed between the customer and the supplier.
4.2.3 Cable impact
Method: IEC 60794-1-2-E4
Radius of striking surface: 12,5 mm
Impact energy: 1,0 J
Number of impacts: at least 3, each separated by at least 500 mm
Requirements: no fibre breakage
NOTE For certain applications specifying MICE classification of ISO/IEC 24702 and related standards, impact
energy values may be agreed between customer and supplier.

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– 10 – 60794-2-20  IEC:2008
4.2.4 Cable bending
Method: IEC 60794-1-2-E11A
Mandrel diameter: 20 times cable diameter
Number of turns per helix: 6
Number of cycles: 10
Requirements: no fibre breakage
NOTE For certain applications specifying MICE classification of ISO/IEC 24702 and related standards, different
mandrel diameter values may be agreed between the customer and the supplier.
4.2.5 Cable repeated bending
Method: IEC 60794-1-2-E6
Bending radius: 20 times cable diameter
Number of cycles: 25
Mass of weights: 4 kg
Requirements: under visual examination without magnification there shall
be no damage to the sheath and to the cable elements
4.2.6 Cable bending under tension
Method: IEC 60794-1-2-E18
Bending radius: 20 times cable diameter
Load: 400 N or weight of 1 km of cable, whichever is greater
Requirements: no change in attenuation after the test, and
there shall be no visible damage to the cable elements
4.2.7 Cable bending at low temperature
Method: IEC 60794-1-2-E11A (see IEC 60811-1-4, Clause 8)
Bending radius: 10 times cable diameter
Test temperature: 0 °C, –10 °C or –15 °C depending on application and
customer requirements
Number of turns per helix: according to Clause 8 of IEC 60811-1-4
Number of cycles: 2
Requirements: in addition to the requirements of Clause 8 of IEC 60811-
1-4, no fibre shall break during the test
4.2.8 Cable flexing
Method: IEC 60794-1-2-E8
Number of cycles: 100
Pulley diameter: 20 times cable diameter
Mass of weights: 2 kg (minimum)
Requirements: no fibre breakage
NOTE For certa
...