IEC 60794-1-31:2018

IEC 60794-1-31 ®
Edition 1.0 2018-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Optical fibre cables –
Part 1-31: Generic specification – Optical cable elements – Optical fibre ribbon

Câbles à fibres optiques –
Partie 1-31: Spécification générique – Éléments de câbles optiques – Rubans de
fibres optiques
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IEC 60794-1-31 ®
Edition 1.0 2018-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Optical fibre cables –
Part 1-31: Generic specification – Optical cable elements – Optical fibre ribbon

Câbles à fibres optiques –
Partie 1-31: Spécification générique – Éléments de câbles optiques – Rubans de

fibres optiques
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.180.10; 33.180.99 ISBN 978-2-8322-6564-2

– 2 – IEC 60794-1-31:2018 © IEC 2018

CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms, definitions, symbols and abbreviated terms . 5
4 Requirements . 6
4.1 General . 6
4.2 Construction . 6
4.2.1 Ribbon structure . 6
4.2.2 Optical fibres . 7
4.3 Dimensions . 7
4.4 Mechanical requirements . 9
4.4.1 General . 9
4.4.2 Separability of individual fibres from a ribbon. 9
4.4.3 Ribbon stripping . 10
4.4.4 Torsion . 10
4.5 Identification of ribbon . 10
4.5.1 General . 10
4.5.2 Identification by positional identification . 10
4.5.3 Identification by ribbon coding and fibre colouring . 11

Figure 1 – Cross-section of a typical edge-bonded ribbon (thinner ribbon) . 6
Figure 2 – Cross-section of a typical encapsulated ribbon (thicker ribbon) . 7
Figure 3 – Overview of a typical partially-bonded ribbon . 7
Figure 4 – Example of cross-sectional drawing illustrating fibre ribbon geometry
(4-fibre ribbon) . 9
Figure 5 – Example of identification by means of colour coding and positioning . 11

Table 1 – Maximum dimensions of optical fibre ribbons for a typical 250 µm coating fibre . 8

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
OPTICAL FIBRE CABLES –
Part 1-31: Generic specification –
Optical cable elements – Optical fibre ribbon

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
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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 60794-1-31 has been prepared by subcommittee SC86A: Fibres
and cables, of IEC technical committee 86: Fibre optics.
This bilingual version (2019-02) corresponds to the monolingual English version, published in
2018-05.
The text of this International Standard is based on the following documents:
CDV Report on voting
86A/1806/CDV 86A/1840/RVC
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.

– 4 – IEC 60794-1-31:2018 © IEC 2018
The French version of this standard has not been voted upon.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the 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 document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document 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.
OPTICAL FIBRE CABLES –
Part 1-31: Generic specification –
Optical cable elements – Optical fibre ribbon

1 Scope
This part of IEC 60794, which is a generic specification, covers optical fibre ribbons.
Requirements which are described in this part apply to optical fibre ribbon cables for use with
telecommunication equipment and devices employing similar techniques, in particular optical
fibre cables in IEC 60794-2 for indoor use and in IEC 60794-3 for outdoor use. Detailed
specifications for each application are given in IEC 60794-2 and IEC 60794-3.
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 of the referenced document (including
any amendments) applies.
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 60794-1-1, Optical fibre cables – Part 1-1: Generic specification – General
IEC 60794-1-23, Optical fibre cables – Part 1-23: Generic specification – Basic optical cable
test procedures – Cable element test methods
IEC 60794-2, Optical fibre cables – Part 2: Indoor cables – Sectional specification
IEC 60794-3, Optical fibre cables – Part 3: Outdoor cables – Sectional specification
3 Terms, definitions, symbols and abbreviated terms
For the purposes of this document, the terms, definitions, symbols and abbreviated terms
given in IEC 60794-1-1 apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp

– 6 – IEC 60794-1-31:2018 © IEC 2018
4 Requirements
4.1 General
Optical fibre ribbons are optical fibres which can be assembled in a composite linear array.
Fibres shall be arranged in parallel and formed into ribbons of typically four, six, eight, twelve,
sixteen, twenty-four or thirty-six fibres each according to user requirements, and shall be
capable of mass splicing.
Some parameters shall be measured in the ribbon since the corresponding tests on the
primary coated fibre or finished cable are not sufficient for complete characterization. These
parameters are identified below.
4.2 Construction
4.2.1 Ribbon structure
Ribbon structures are typically designated as edge-bonded, encapsulated or partially-bonded.
Edge-bonded and encapsulated structures are differentiated by the amount of buffering
afforded to the fibres by the bonding agent. The partially-bonded ribbon may be of either
structure but with the buffer applied periodically.
Figure 1 illustrates the edge-bonded structure in which the bonding agent is applied
predominantly between the fibres. Figure 2 illustrates the encapsulated structure in which the
bonding agent extends well beyond the extreme surface of any fibre. Figure 3 illustrates the
partially-bonded structure in which neighbouring fibres are fixed together periodically in the
longitudinal direction.
The edge-bonded and encapsulated ribbons are predominantly rigid in the transverse
direction. The partially-bonded structure enables the optical fibre ribbon to be rolled up easily
and accommodated very tightly in cables.
or
IEC
Figure 1 – Cross-section of a typical edge-bonded ribbon (thinner ribbon)

or
IEC
Figure 2 – Cross-section of a typical encapsulated ribbon (thicker ribbon)
Not bonded
Bonded
IEC
Figure 3 – Overview of a typical partially-bonded ribbon
4.2.2 Optical fibres
Category A1 multimode fibres which meet the requirements of IEC 60793-2-10 or Category B
single-mode optical fibres which meet the requirements of IEC 60793-2-50 shall be used.
Diameter over the fibre coating is typically 250 µm. Other fibres may be used to construct
ribbons meeting the intent of this specification.
NOTE Dimensions for ribbons with fibre coatings other than the typical 250 µm can be established between the
customer and supplier. There exist alternative coating diameters (such as 200 µm) which can be used and require
additional considerations with respect to connectivity and tools.
4.3 Dimensions
Unless otherwise specified in the detail specification, the maximum dimensions and the
structural geometry of optical fibre ribbons shall be as shown in Table 1. The definitions of
each dimension are defined in IEC 60794-1-23 and illustrated in Figure 4.

– 8 – IEC 60794-1-31:2018 © IEC 2018
Table 1 – Maximum dimensions of optical fibre ribbons for
a typical 250 µm coating fibre
Number Width Height Fibre alignment
a
of fibres
Extreme fibres Planarity
w h b p
µm µm µm µm
4 1 220 360 786 50
6 1 648 360 1 310 50
c
8 2 300 380 1 834 50
12 3 400 380 2 882 75
b b
16 4 400 380 Per 8-fibre unit Per 8-fibre unit
b b
24 6 500 380 Per 12-fibre unit Per 12-fibre unit
d e b b
32 4 400 ffs Per 8-fibre unit Per 8-fibre unit
b b
36 9 800 380 Per 12-fibre unit Per 12-fibre unit
If the ribbon has flexibility, for example in the case of having a partially-bonded configuration, the dimensions of
the ribbon should be measured under the condition of which tested ribbon is aligned to be a coplanar. The
example of a typical partially-bonded ribbon is illustrated in Figure 3.
a
Dimensions for other ribbons with fibre counts not listed above should be established between the customer
and supplier.
b
Per unit values are measured with the ribbon separated into the intended sub-units.
c
Maximum width shall be 2 300 in case the 8-fibre ribbon can be separated into two four-fibre sub-units.
d
A thirty-two-fibre ribbon consists of two layers of sixteen-fibre ribbons.
e
ffs= for further specification.

a
d
b
w
IEC
Key
a diameter of a coloured fibre
w width of that area
h height of that area
d distance between adjacent fibres
b distance between the extreme fibres
p planarity of the ribbon which is defined as the sum of the absolute values of the maximum positive and
maximum negative vertical separation from the basis line
Considering the precision of fibre geometric attributes and the relatively larger precision of ribbon geometry
requirements, it is acceptable for glass core/glass cladding fibres to use the edge of the cladding for the
measurements according to Table 1, and as illustrated in Figure 4, in lieu of the fibre centres. In this case, the
measurements shall be made on the same side of all fibres (e.g. top or bottom, left or right side). This is consistent
with IEC 60794-1-23, method G2.
NOTE The maximum dimensions and the structural geometry of optical fibre ribbons for a typical 200 µm coating
fibre are currently under study.
Figure 4 – Example of cross-sectional drawing illustrating
fibre ribbon geometry (4-fibre ribbon)
More stringent requirements may be agreed between the customer and supplier, as needed,
depending on the splice or the connector technique employed.
The dimensions and structural geometry can be verified with a type test, described as the
visual measurement method (IEC 60794-1-23, method G2), to establish and assure proper
control of the ribbon manufacturing process. Once the process is established, and in order to
ensure functional performance, the width and height of the ribbons may be controlled and
verified, for final inspection purposes, with an aperture gauge (IEC 60794-1-23, method G3)
or by the visual measurement method.
4.4 Mechanical requirements
4.4.1 General
Detailed specifications of an optical fibre ribbon shall be verified by application, such as
indoor and outdoor use, which are described in the sectional specifications documents for
optical cables. Optical fibre ribbon shall satisfy specifications and be tested as indicated
below.
4.4.2 Separability of individual fibres from a ribbon
Fibre breakout capability at some level is generally required. Some ribbons of any type may
be intended to be separated into predefined units. Specific requirements for breakout and
separability shall be as specified in the detail specifications.

p
h
– 10 – IEC 60794-1-31:2018 © IEC 2018
The ribbons shall be constructed in such a way that fibres can be separated from the ribbon
construction, into sub-units or individual optical fibres, as specified in the detail specification,
while meeting the following criteria:
• the ribbon shall be tested for the ability to break out individual fibres using the tear
(separability) test shown in IEC 60794-1-23, method G5, or a method agreed upon
between the customer and supplier;
• end breakout shall be accomplished without specialized tools or apparatus;
• mid-span breakout shall be accomplished following the ribbon manufacturers' procedures;
• the fibre breakout procedure shall not be permanently detrimental to the optical and
mechanical performance of the fibre;
• any colour coding of fibres shall remain sufficiently intact within any 25 mm segment to
enable individual fibres to be distinguished from each other.
4.4.3 Ribbon stripping
The coating of individual fibres as well as the residual ribbon bonding material shall be easily
removable by an adequate stripping method, preferably thermal stripping. The ribbon bonding
materials and primary coating layers should be removed as a "strip" to avoid excess dust
generation. The method of removal shall be agreed between the customer and supplier or
shall be defined in the detail specification.
4.4.4 Torsion
The mechanical and functional integrity of a fibre ribbon can be verified by carrying out the
torsion test shown in IEC 60794-1-23, method G6.
4.5 Identification of ribbon
4.5.1 General
Each fibre within a ribbon cable shall be uniquely identifiable using some scheme of ribbon
identification and fibre identification within a ribbon. Common schemes include ribbon coding
by printed legends, ribbon positioning (tubes, slots, etc.), fibre positional colour coding, colour
coded matrix, and fibre colour coding within a ribbon. The scheme shall be defined in the
detail specification.
4.5.2 Identification by positional identification
If positional identification is specified, the scheme may follow the scheme described below
and illustrated in Figure 5. The fibre shall be distinguishable by means of colour coding and
positioning. For example (see Figure 5):
a) a fibre ribbon has an identification coloured fibre on one side of the ribbon and a sub-
identification coloured one on the other side or has two identification coloured fibres on
one side. A sub-identification colour code can be used when the optical fibre ribbons are
larger in number than the identification colour code;
b) any colour of the identification fibre colours group is different from that of the sub-
identification fibre colours group. The side of the identification colours group corresponds
to fibre no. 1 in the ribbon;
c) the colour types and the order used for identification and sub-identification should be
agreed between the customer and the supplier. The colours of the other fibres shall be
agreed between the customer and the supplier;
d) the colour rang
...