IEC 61756-1:2019

IEC 61756-1 ®
Edition 2.0 2019-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Fibre optic interconnecting devices and passive components – Interface
standard for fibre management systems –
Part 1: General and guidance
Dispositifs d'interconnexion et composants passifs fibroniques – Norme
d'interface pour les systèmes de gestion de fibres –
Partie 1: Généralités et recommandations

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IEC 61756-1 ®
Edition 2.0 2019-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Fibre optic interconnecting devices and passive components – Interface

standard for fibre management systems –

Part 1: General and guidance
Dispositifs d'interconnexion et composants passifs fibroniques – Norme

d'interface pour les systèmes de gestion de fibres –

Partie 1: Généralités et recommandations

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.180.01 ISBN 978-2-8322-7511-5

– 2 – IEC 61756-1:2019 © IEC 2019
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
3.1 Fibre management related definitions . 6
3.2 Component related definitions . 9
3.3 Protective housing related definitions . 11
4 Abbreviated terms . 12
5 Description of a fibre management system . 13
6 Parts and functions of a fibre management system . 14
6.1 General . 14
6.2 Splice trays . 15
6.3 Minimum bending radius for stored fibres . 16
6.4 Splice protector . 19
6.5 Splice holder . 20
6.6 Guiding elements . 21
6.7 Patchcords and pigtails . 22
6.8 Identification of fibres, fibre tubes or single elements . 22
7 Other factors relevant to fibre management systems . 22
7.1 Re-entry and access . 22
7.2 Quality of mouldings . 22
7.3 Polymer materials . 22
7.4 Marked or colour coded parts . 22
Annex A (informative) Use of flow chart for calculation of the minimum bending radius
for stored fibres . 23
A.1 Example of calculation minimum bending radius . 23
A.2 Results for various fibre types with a 1 m storage length . 28
A.3 Results for various fibre types with 2 m storage length . 29
Bibliography . 31

Figure 1 – Multiple element management system . 7
Figure 2 – Single circuit management system. 8
Figure 3– Single element management system . 8
Figure 4– Patchcord . 11
Figure 5– Pigtail . 11
Figure 6 – Functional parts diagram of a protective housing. 13
Figure 7 – Functional parts diagram of FMS . 14
Figure 8 – Typical required failure probabilities of various networks . 17
Figure 9 – Lifetimes per bent fibre metre versus failure probability for various
bending radii . 18
Figure 10 – Flow chart for minimum bending radius of stored fibres . 19
Figure 11 – F type splice protector . 20
Figure 12– S type splice protector. 20
Figure 13 – M type fibre splice . 20

Figure A.1 – Step 1: Find radius that matches the failure probability target requirement. 23
Figure A.2 – Find bending radius for specified failure probability target and fibre length . 24
Figure A.3 – Step 2: Estimate the maximum attenuation increase for bending radius . 25
Figure A.4 – Estimated maximum attenuation increase for bending radius of 15 mm . 25
Figure A.5 – Step 3: Compare estimated maximum attenuation with requirement . 26
Figure A.6 – Estimated attenuation increase for bending radius of 20 mm . 27
Figure A.7 – Step 5: Check the estimated attenuation with requested maximum limit . 28
Figure A.8 – Estimated maximum attenuation increase for bending radius . 29

Table 1 – Optical fibre fusion splice protectors – Outline and nominal dimensions . 20
Table 2 – Mechanical fibre splices – Outline and nominal dimensions . 20
Table A.1 – Minimum bending radius for storage of the various fibre types with typical
mechanical failure probability targets for different network locations and fibre storage

length of 1 metre and maximum attenuation increase of 0,05 dB at 1 625 nm . 29
Table A.2 – Minimum storage radius for the various fibre types with typical mechanical
failure probability targets for different network locations and fibre storage length of 2
metres and maximum allowed attenuation increase of 0,1 dB at 1 550 nm . 30

– 4 – IEC 61756-1:2019 © IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIBRE OPTIC INTERCONNECTING
DEVICES AND PASSIVE COMPONENTS –
INTERFACE STANDARD FOR FIBRE MANAGEMENT SYSTEMS –

Part 1: General and guidance
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
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Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
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6) All users should ensure that they have the latest edition of this publication.
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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 61756-1 has been prepared by subcommittee 86B: Fibre optic
interconnecting devices and passive components, of IEC technical committee 86: Fibre optics.
This second edition cancels and replaces the first edition published in 2006. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) addition of figures to show the interface between protective housing and fibre management
system;
b) addition of definitions for protective housing, closure, box, street cabinets and optical
distribution frame modules;
c) addition of table with dimensions of fusion splice protectors and mechanical splices;
d) addition of method to identify the minimum bending radius for stored fibres;

e) addition of clause for other factors relevant to fibre management systems;
f) addition of annex A for example of calculating the minimum bending radius of stored fibres
in a fibre management system.
The text of this International Standard is based on the following documents:
FDIS Report on voting
86B/4228/FDIS 86B/4240/RVD
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.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
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.

– 6 – IEC 61756-1:2019 © IEC 2019
FIBRE OPTIC INTERCONNECTING
DEVICES AND PASSIVE COMPONENTS –
INTERFACE STANDARD FOR FIBRE MANAGEMENT SYSTEMS –

Part 1: General and guidance
1 Scope
This part of IEC 61756 covers general information on fibre management system interfaces. It
includes the definitions and rules under which a fibre management system interface is created
and it provides also criteria to identify the minimum bending radius for stored fibres.
This document allows both single-mode and multimode fibre to be used.
Liquid, gas or dust sealing requirements at the cable entry area or cable element ending are
not covered in this document.
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 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
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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
3.1 Fibre management related definitions
3.1.1
distribution element
element for a fibre management system providing fibre branching, holding and distribution
function
3.1.2
fibre management system
system to control, protect and store splices, connectors, passive optical components and fibres
from incoming to outgoing cables

Note 1 to entry: A fibre management system is intended for installation within a protective housing.
Note 2 to entry: A fibre management system is often called an "organiser".
3.1.3
multiple element
physical fibre separation level consisting of more than one single element
Note 1 to entry: This separation level has fibres from multiple cable elements on one splice tray and is also called
mass storage. It is the lowest (worst) degree of physical circuit separation.
3.1.4
multiple element management system
system which provides all necessary equipment to connect a defined number of incoming and
outgoing fibres/cables
Note 1 to entry: It comprises storage and protection of fibres/ribbons and interconnections in one tray for more than one
single element (see Figure 1).
Note 2 to entry: There are many different names for this structure, for example " mass storage". In this document,
" multiple element" will be used.

Figure 1 – Multiple element management system
3.1.5
multiple ribbon
multiple element consisting of multiple optical fibres (circuits) arranged in ribbons (fibres in
parallel) which are also arranged (for example, in stacks)
3.1.6
optical performance stability
stability of the system to transient loss introduced by external disturbances of the fibres
3.1.7
single circuit
physical fibre separation level where the optical circuit consists of one fibre (single fibre), or
more than one fibre, providing all services for one subscriber
Note 1 to entry: This fibre separation level has the fibre(s) of only one customer on one splice tray. It is the highest
(best) degree of physical circuit separation.
3.1.8
single circuit management system
system which provides all necessary equipment to connect a defined number of incoming and
outgoing fibres/cables
– 8 – IEC 61756-1:2019 © IEC 2019
Note 1 to entry: It comprises storage and protection of fibres/ribbons and interconnections with one single circuit
per splice tray (Figure 2).
Note 2 to entry: Disturbance of operational circuits by accessing any other adjacent circuit should be minimised.
The disturbance should stay within allowable tolerances given in related performance standards.

Figure 2 – Single circuit management system
3.1.9
single element
physical fibre separation level in the cable subassembly comprising one or more optical fibres
inside a common covering for example in a tube or inside one groove of a grooved cable (slotted
core cable)
Note 1 to entry: A single element provides services to more than one subscriber.
Note 2 to entry: This fibre separation level has all fibres from a cable element (e.g. loose tube) on one splice tray.
It is an intermediate degree of physical circuit separation (between single circuit and multiple element).
3.1.10
single element management system
system which provides all necessary equipment to connect a defined number of incoming and
outgoing fibres/cables
Note 1 to entry: It comprises storage and protection of fibres/ribbons and interconnections in one tray for each
single element (see Figure 3).

Figure 3– Single element management system
3.1.11
single ribbon
single element designed to carry all fibres of one ribbon

Note 1 to entry: Depending on the fibres deployment’, a single ribbon can contain all the fibres of one circuit (single
circuit) or the fibres of more than one circuit (single element).
3.1.12
splice tray
structure that organises and controls storage of fibre splices in an orderly manner, together with
the associated excess uncabled fibre length
Note 1 to entry: It can be a part of a fibre management system.
3.1.13
transient loss
short term (ms) reversible change of optical transmission characteristics arising from optical
discontinuity, physical defects and modifications of the attenuation (e.g. bending loss) normally
caused by mechanical stress
3.1.14
uncut fibre
fibres from a continuous cable with the cable sheath removed over a defined length without
cutting the fibres or tubes
Note 1 to entry: The uncut tubes or fibres are stored e.g. in a space saving loop. When required, the fibres are cut
and spliced or connected.
3.2 Component related definitions
3.2.1
active optical component
optical component exhibiting one or more of the following functions:
– generation or detection of optical power;
– conversion of an electronic signal to a corresponding optical one or vice versa;
– optical amplification or optical regeneration (2R or 3R) of an optical signal;
– direct conversion of the optical frequency of an optical signal
3.2.2
adapter
component in which two or more ferrules are aligned
Note 1 to entry: A ferrule is the fibre holding component part of the plug.
[SOURCE: IEC 60874-1:2011, 3.1, modified – The note has been added.]
3.2.3
fan-out
passive optical component providing a transition between a single ribbon or single element into
individual fibres
3.2.4
fusion splice
permanent joint accomplished by the application of localised heat sufficient to fuse or melt the
ends of two lengths of optical fibre, to produce a continuous single optical fibre
[SOURCE: IEC 60050-731:1991, 731-05-06, modified – The words "a splice" has been replaced
by "permanent joint".]
3.2.5
fusion splice protector
component which protects the weak fusion zone and the bare fibres of a fusion splice

– 10 – IEC 61756-1:2019 © IEC 2019
Note 1 to entry: The most common types used in fibre management systems are heat shrinkable or mechanical
fusion splice protectors.
3.2.6
live fibre
transmitting fibre
fibre optical circuit that is carrying an optical signal
3.2.7
mechanical splice
fibre splice accomplished by fixtures or materials, rather than by thermal fusion
[SOURCE: IEC 60050-731:1991, 731-05-07]
3.2.8
non-transmitting fibre
optical circuit that is not carrying an optical signal
3.2.9
optical connector set
complete assembly of components required to provide demountable coupling between optical
fibres
[SOURCE: IEC 60874-1:2011, 3.15, modified – The word "fibre" has been deleted from the term,
and the definition has been rephrased.]
3.2.10
optical fibre connector
component normally attached to an optical cable or piece of apparatus for the purpose of
providing optical interconnection and disconnection of optical fibres or cables
Note 1 to entry: The interconnection usually consists of two plugs mated together in an adapter or 1 plug mated in
a socket.
[SOURCE: IEC 60050-731:1991, 731-05-01, modified – The definition has been rephrased, and
the note added.]
3.2.11
optical fibre splice
permanent or separable joint whose purpose is to couple optical power between two optical
fibres, realised by either a fusion or a mechanical technique
[SOURCE: IEC 60050-731, 731-05-05, modified – The words "or separable" and "realised by
either a fusion or a mechanical technique" have been added.]
3.2.12
passive optical component
optical component or assembly which does not require any source of energy for its operation
other than optical input signals
Note 1 to entry: A passive optical component might need external power to control the stability of its optical
characteristics. Example is controlling the temperature of the component.
Note 2 to entry: A passive optical component never generates an optical gain of signal power.
[SOURCE: IEC TS 62538 modified]
3.2.13
patchcord
length of optical fibre or cable, permanently terminated at both ends with a plug

Note 1 to entry: See Figure 4.

Figure 4– Patchcord
[SOURCE: IEC 60874-1:2011, 3.17, modified –The words "optical fibre" and "or jumper" have
been deleted from the term. The note and figure have been added.]
3.2.14
pigtail
length of optical fibre or cable, permanently terminated at one end with a plug
Note 1 to entry: See Figure 5.

Figure 5– Pigtail
[SOURCE: IEC 60874-1:2011, 3.18, modified –The words "optical fibre" have been deleted from
the term. The note and figure have been added.]
3.2.15
plug
male-type part of an optical fibre connector
Note 1 to entry: Optical fibre connectors are either two plugs mated in an adapter or one plug mated into a socket
(female part).
[SOURCE: IEC 60874-1:2011, 3.20, modified – The words "fibre optic" have been added to the
definition, and the note has been added.]
3.3 Protective housing related definitions
3.3.1
box
free breathing protective housing that is permanently attached to a vertical wall or pole
Note 1 to entry: A box is not specifically designed to allow cable movement (e.g. torsion, bending) at the cable ports
during operation.
3.3.2
free breathing closure
protective housing that allows a free exchange of air with the environment
Note 1 to entry: A free breathing closure may look like a sealed closure, but it is not designed to hold a varying
overpressure or underpressure caused by temperature changes or atmospheric pressure changes. Free breathing
closures are used in aerial environments for the interconnection of cables.
Note 2 to entry: Limited water ingress and/or limited dust ingress is possible. Free breathing closures are not
intended for use in areas that are subject to flooding or water immersion.
[SOURCE: IEC 61753-1:2018]
3.3.3
optical distribution frame module
sub rack
protective housing which is mountable in a supporting structure

– 12 – IEC 61756-1:2019 © IEC 2019
Note 1 to entry: An optical distribution frame module contains a fibre management system and can provide
rearrangeable interconnections between the fibres of the incoming and outgoing cables.
Note 2 to entry: The supporting structure that houses the ODFM is often called an equipment rack.
[SOURCE: IEC 61753-1:2018, 3.10, modified – The second preferred term "sub rack" has been
added, and the word "protective" has been added in the definition.]
3.3.4
protective housing
indoor or outdoor housing utilised for the storage, distribution or protection of one or more cable
joints or any passive or active components
Note 1 to entry: Examples of protective housings: closures, wall boxes, cabinets, cases, optical distribution frame
modules, sub racks or pedestals. A closure can be either a "sealed closure" or a "free breathing closure".
Note 2 to entry: The protective housing contains a fibre management system.
[SOURCE: IEC 61753-1:2018, 3.16, modified – The definition and Note 1 have been rephrased,
and the figure has been deleted.]
3.3.5
sealed closure
watertight and dust-tight housing that can hold a varying overpressure or underpressure caused
by temperature changes or atmospheric pressure changes
Note 1 to entry: There is no exchange of air with the outside environment when exposed to temperatures over the
specified operating temperature range.
Note 2 to entry: Although often referred to as hermetic sealed closures, humidity can enter the inner closure by
diffusion.
Note 3 to entry: Sealed boxes or sealed wall outlets shall be treated as sealed closures.
Note 4 to entry: Complete inner filled housings are also considered to be sealed closures.
[SOURCE: IEC 61753-1:2018, 3.17]
4 Abbreviated terms
CO central office
CWDM coarse wavelength division multiplexer
DWDM dense wavelength division multiplexer
FMS fibre management system
FTTH fibre to the home
ME multiple element
MR multiple ribbons
OADM optical add drop multiplexer
ODFM optical distribution frame module
SC single circuit
SE single element
SR single ribbon
WWDM wide wavelength division multiplexer

5 Description of a fibre management system
A fibre management system is typically installed inside a protective housing, normally a closure,
wall box, distribution frame or street cabinet. Figures 6 and 7 illustrate and define the interface
between the Fibre Management System and the protective housing.

Key
1 Cable sealing (required for outside plant, optional for indoor application)
2 Cable anchorage
3 Cable blocking (optional)
Gas blocking (optional)
5 Distribution element (optional)
6 Grounding (optional)
7 Fixing point for FMS in protective housing
8 Air pressure valve (input or overpressure exhaust) (optional)
Figure 6 – Functional parts diagram of a protective housing

– 14 – IEC 61756-1:2019 © IEC 2019

Key
1 Splice tray
2 Fixing (optional), distribution and guiding element
3 Non spliced or uncut fibre storage (optional)
4 Passive optical component (optional)
5 Tray holder
6 Patch panel (connectors) (optional)
7 Cable element storage (optional)
Figure 7 – Functional parts diagram of FMS
6 Parts and functions of a fibre management system
6.1 General
A fibre management system (FMS) contains all necessary functions related to distribution,
junction or connection between the fibres of incoming and outgoing cables.
The minimum content of a fibre management system are the parts fulfilling the functions of
splice tray, fibre storage and guiding elements. For single circuit systems, the distribution
element is also needed. Other functional parts, like passive or active optical components,
optical connector sets or cable element storage devices, are optional. The following passive
and active optical components are recognised but not limited to:
– splicing sub-assemblies;
– splitter sub-assemblies;
– connector patch tray or patch panel sub-assemblies;
– coarse wavelength division multiplexer (CWDM), dense wavelength division multiplexer
(DWDM), wide wavelength division multiplexer (WWDM) or grating sub-assemblies;
– ribbon fan-out assemblies;
– erbium doped fibre amplifier assemblies;
– OADM sub-assemblies.
For fibre management systems that are intended to be re-accessible while the network remains
live, it is recommended to evaluate the optical performance stability by transient loss
measurements as described in IEC 61753 (all parts).
Sections 6.2 to 6.8 describe parts which are used in FMS and their functions.

6.2 Splice trays
There are many designs of splice trays, some of which can be used in different configurations
such as single circuit (SC), single element (SE) or multiple element (ME) fibre separation levels.
All trays have cable and/or fibre entry ports. If they have only one entry port for incoming and
outgoing fibre, the tray shall have a reverse path guiding possibility (figure of eight). All other
tray types may have this guiding for other reasons.
Fibre over-length is typically stored in the same tray as the splices. Over-length will permit the
movement of the splice to the splicing equipment or tools and back to the splice holder. If
reconfiguration is necessary, the over-length should be sufficient to allow re-routing and storage
of a splice in any defined splice position in the fibre management system as required. Therefore,
the stored fibre lengths should be such that it allows at least six re-splices. Often the fibres are
stored in loops near the splice area. For optimised handling, and to avoid compromising
minimum bending radius, guiding elements are needed. This guiding function can be achieved
in various ways, for example from each individual channel or slot or one guiding area for all
fibres. The guiding function shall protect each fibre against damage during normal use and from
environmental conditions, to avoid compromising minimum bending radius.
For some applications, it may be necessary to store uncut fibres or to separate them from other
fibres in a tray. After cutting, the remaining ends should be sufficiently long to be handled in
the same way as the splice over-length. For some applications, non-transmitting fibre ends
need to be stored. Depending on the future use, they may be mass stored, by element, or
individually. This can be done in different areas inside or outside the fibre management system
or in a splice tray.
A splice tray provides a place for one or more splice holders. This function can be a part of the
tray or provided by separately fixed splice holders. Different types are specified by
– the splice count,
– the splice protection type, and
– the fixing method.
For fixing or stacking the splice trays, different methods are possible.
The minimum number of fusion splice protectors or mechanical splices in a splice tray shall be
for SC – 2, SR – 1, SE – 12, ME – 24 and MR 2. To achieve the minimum number of splices
per tray, multiple splice holders may be used.
Each type of management system can have splice trays containing extra parts to improve or to
provide additional functions. These functions, for example covers, hinges or fixing elements,
shall be described in the relevant document.
Trays shall be easily inserted into or removed from the FMS and fixed positively in place with a
locking mechanism. The locking mechanism shall be able to be used and re-activated, at least
10 times without loss of functionality. The trays should allow control over fibre handling to avoid
damage to the fibres or signal loss. Full control over fibre handling by a single operator shall
be achieved, typically without using special tools not supplied with the FMS product during
installation.
The tray interface fixing device shall be robust and durable under service conditions. Fragile or
loose fitting trays may allow the tray to flex or move around; risking either tray or fibre damage
should it fall out of the FMS in service.
It is possible to combine different fibre separation levels (SC, SE, ME) in one fibre management
system. The splice tray profiles are typically the same across various fibre separation levels of
tray design with the heights of each type typically differing. This concept has the advantage of

– 16 – IEC 61756-1:2019 © IEC 2019
fixing different trays to a common back plate on the FMS if the fixing points are of an incremental
pitch design.
If the thickness of an SC tray is one unit then typically tray thicknesses of 2 units are used for
SE/SR trays and 2 units or more for ME/MR trays. To accommodate larger passive or active
optical components, tray thickness of 3 or more units may be used.
6.3 Minimum bending radius for stored fibres
Fibre storage is typically used for
– spliced fibres with reserve length for resplicing,
– non-spliced fibres,
– uncut fibres,
– patchcords and pigtails (but not together with the fibres),
– reserve length for future needs, and
– providing protection to fibres.
Over-length is typically stored in a fibre management system as a fibre, cabled fibre or single
element (loose tubes). Fibre can be stored in a splice tray as spliced fibre, uncut or cut fibre.
Cabled fibre, buffered fibre or single elements can be stored in storage trays or baskets.
The minimum bending radius for stored fibres is derived from the long term mechanical reliability
of permanent bent fibres and depends on the expected mechanical failure probability targets.
Typical targets depend on the network type (see Figure 8):
– long haul, core and metropolitan networks (very high reliability with a failure probability
-7
target less than 10 over the expected lifetime of 20 years);
-6
– access networks (networks with failure probability target less than 10 over the expected
lifetime of 20 years);
– distribution and drop cable networks (acceptable reliability with failure probability target less
-5
than 10 over the expected lifetime of 20 years);
-5
– data centres (failure probability target less than 10 over the expected lifetime of 20 years).

Figure 8 – Typical required failure probabilities of various networks
IEC TR 62048 provides the information of the mechanical failure probability of a 1 m long fibre
bent at various bending radii and expected lifetimes (see Figure 9). The failure probability
values shown in Figure 9 are valid for IEC 60793-2-10 and IEC 60793-2-50 fibres with a 125 µm
cladding diameter.
– 18 – IEC 61756-1:2019 © IEC 2019

Source: IEC TR 62048.
Figure 9 – Lifetimes per bent fibre metre versus failure
probability for various bending radii
The minimum storage radius of fibres in an FMS depends on
– the required failure probability target (location in the network),
– the length of fibre to be stored,
– the fibre type,
– the longest wavelength of transmission, and
– the maximum allowed attenuation increase (macro bending loss).
Once all this information is known, the flow chart in Figure 10 can be followed to obtain the
minimum bending radius of the stored fibres. An example is given in Annex A of how to use this
flow chart.
Figure 10 – Flow chart for minimum bending radius of stored fibres
6.4 Splice protector
The three most common types of splice protection are the following:
– heat shrink fusion splice protection (S type);
– metal or polymer crimp splice fold-over protection (F type);
– complete solutions containing a mechanical splice (M type).
Other methods for splice protection are also possible (e.g. recoating of fibres or capillary sleeve
protection).
Splice protector types requiring a splice holder can be found (with nominal dimensions) in
Figures 11, 12 and 13, and in Tables 1 and 2.

– 20 – IEC 61756-1:2019 © IEC 2019
Table 1 – Optical fibre fusion splice protectors – Outline and nominal dimensions
Product as installed or fully recovered
Available lengths
W H
Type Fibre L
mm mm
mm
F1 Single fibre 30
1,2 3,2
S1-12 Single fibre 1,25 1,25 15/20/25/30

S1-13 Single fibre 15/20/25/30
1,3 1,3
Figure 11 – F type splice protector S1-16 Single fibre 1,6 1,5 15/20/25/30/40
S1-22 Single fibre 2,2 2,2 25/30/35/40/45
S1-24 Single fibre
2,4 2,4 20/23/25/35/40/45/60
S1-26 Single fibre 2,6 2,6 23/35/40/45/60
S1-32 Single fibre
3,2 3,2 45/60
S1-37 Single fibre 3,7 3,7 68
S2-37 Ribbon 4
3,7 3,5 40/45
S3-40 Ribbon 8 4,0 3,7 40/45
S4-45 Ribbon 12 4,5 4,0 25/30/40/45

Figure 12– S type splice protector

Table 2 – Mechanical fibre splices – Outline and nominal dimensions

Type Fibre W H L
mm mm mm
M1 Single fibre 3,8 6,4 38
M2 Single fibre 4,0 4,0 36
M3 Single fibre 3,2 3,2 45
M4 Single fibre 4,2 4,2 44
M5 Single fibre 4,0 4,0 40
M6 Single fibre Ø 5,0 65
Figure 13 – M type fibre splice

6.5 Splice holder
A splice holder is a device in which a number of protected optical fibre splices are stored. A
splice holder can be an integral part of the splice tray, for example moulded fins to receive fibre
splice protectors, or supplied as a separate insert. A separate insert can be mechanically (e.g.
by snapping or screwing) or chemically (e.g. by using a self-adhesive pad or other adhesive
materials) fixed into the splice tray. Standard interface sizes for these inserts are recommended
for easy replacement. The material of the insert that holds a splice protector may be solid plastic,
flexible rubber or cellular foam. The minimum number of re-splices shall be 6 per splice holder
fixing.
...