SIST-TS CLC/TS 50621:2016

SLOVENSKI STANDARD
01-september-2016
6PHUQLFD]DSRSUDYLORSRãNRGRYDQLKYJUDMHQLKRSWLþQLKNDEORYLQPLNURNDQDORY
Guideline for the repair of damaged installed optical fibre cables and microducts
Leitfaden für die Instandsetzung von beschädigten Lichtwellenleiterkabeln und
Mikrorohren
Guide pour la réparation des câbles à fibre optique endommagés dans les installations
de câbles - Principes
Ta slovenski standard je istoveten z: CLC/TS 50621:2016
ICS:
33.180.10 2SWLþQDYODNQDLQNDEOL Fibres and cables
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

TECHNICAL SPECIFICATION CLC/TS 50621

SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
June 2016
ICS 33.180.10
English Version
Guideline for the repair of damaged installed optical fibre cables
and microducts
Guide pour la réparation des câbles à fibre optique Leitfaden für die Instandsetzung von beschädigten
endommagés dans les installations de câbles - Principes Lichtwellenleiterkabeln und Mikrorohren
This Technical Specification was approved by CENELEC on 2016-04-25.

CENELEC members are required to announce the existence of this TS in the same way as for an EN and to make the TS available promptly
at national level in an appropriate form. It is permissible to keep conflicting national standards in force.

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
© 2016 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. CLC/TS 50621:2016 E
Contents Page
European foreword . 5
Introduction . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions and abbreviations . 7
3.1 Terms and definitions . 7
3.2 Abbreviations . 8
4 Optical fibre cable network. 9
4.1 General . 9
4.2 Optical fibre cable . 9
4.2.1 General . 9
4.2.2 Loose buffer tube cable . 9
4.2.3 Microduct optical fibre cables for blowing . 11
4.2.4 Dimensions for microducts and multi-duct bundles . 11
4.2.5 Optical fibre . 12
4.3 Types of installation of optical fibre cables . 12
4.3.1 General . 12
4.3.2 Installation by direct burial . 13
4.3.3 Installation in conduits . 13
4.3.4 Installation in troughs . 13
4.3.5 Installation in building . 13
5 Summary of damage and repair solutions . 13
6 Damage . 15
6.1 Strain-related damage . 15
6.1.1 General . 15
6.1.2 Disruption . 15
6.1.3 Elongation . 15
6.2 Strain-free damage. 15
6.2.1 General . 15
6.2.2 Cuts through optical fibre cable or microduct . 15
6.2.3 Deformation . 15
6.2.4 Heat and fire . 15
6.2.5 Cuts to optical fibre cable or microduct . 16
7 Effects of damage . 16
7.1 General . 16

7.2 Effect on the mechanical cable design . 16
7.3 Impact on optical parameter . 16
8 Repair . 17
8.1 General . 17
8.2 Interim repair solutions . 17
8.2.1 General . 17
8.2.2 Service re-route . 17
8.2.3 Bypass . 17
8.2.4 Local insertion . 17
8.2.5 Axial closure . 17
8.2.6 Protection against ingress of contamination . 18
8.3 Final repair solutions . 18
8.3.1 Axial closure . 18
8.3.2 Cable segment replacement . 18
8.3.3 Microduct segment replacement . 18
9 Repair acceptance inspection and testing . 19
9.1 General . 19
9.2 Interim repair solutions . 19
9.2.1 Service re-route . 19
9.2.2 Bypass . 19
9.2.3 Local insertion . 19
9.2.4 Ingress protection for microducts – Inspection and testing . 19
9.3 Final repair solutions . 20
9.3.1 Axial closure . 20
9.3.2 Cable segment replacement . 20
9.3.3 Microduct segment replacement – Inspection and testing. 20
Annex A (informative)  Attenuation of fibre splices and effects of PMD . 21
Annex B (informative) Examples of microducts suitable for installation of microduct
optical fibre cables and in combination with conventional ducts . 23
Annex C (informative) List of European Standards . 25
Bibliography . 27

Table of Figures
Figure 1 — Schematic of cabling and microduct structures . 9
Figure 2 — Example of central loose buffer tube cable . 10
Figure 3 — Example cross-section of a central loose buffer tube cable . 10
Figure 4 — Example of stranded loose buffer tube cable . 10
Figure 5 — Example cross-section of stranded loose buffer tube cable . 11
Figure 6 — Microduct with blown microduct optical cable . 11
Figure 7 — Examples of microducts/microduct bundles . 12
Figure 8 — Schematic of silica optical fibre structure . 12
Figure A.1 — Influence of PMD on the transmission in the optical fibre . 21
Figure A.2 — Typical maximum network length dependence on PMD coefficient values
for different bitrates . 22
Table of Tables
Table 1 — Damage-Repair Matrix . 14
Table A.1 — PMD Background (IEC 61282–9; IEC 60793–1-48) . 21
Table B.1 — Microducts vs. application . 24

European foreword
This document (CLC/TS 50621:2016) has been prepared by CLC/TC 86A “Optical fibres and optical fibre
cables”.
The following date is fixed:
• latest date by which the existence of (doa) 2016-10-25
this document has to be announced
at national level
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Introduction
This Technical Specification specifies the processes to be employed for the repair of damage to installed
optical fibre cabling by reinstatement of the outer sheath or the replacement of an optical fibre cable between
existing closures with the objective of restoring its pre-damaged performance and in order to maintain
pathway capacity.
Interim repair procedures including temporary and/or partial repairs, including the introduction of additional
joints of connections, which deliver the minimum functionality to meet immediate performance requirements,
are also described.
In addition, this Technical Specification describes the type and impact of damage leading to the repair
processes specified.
The repair processes specified are applicable to all installation environments except optical ground wires
(OPGW) or optical phase conductors (OPPC).
1 Scope
This Technical Specification specifies the processes to be employed for the repair of damage to installed
optical fibre cabling by reinstatement of the outer sheath or the replacement of an optical fibre cable between
existing closures with the objective of restoring its pre-damaged performance and in order to maintain
pathway capacity.
Interim repair procedures, including temporary and/or partial repairs including the introduction of additional
joints of connections, which deliver the minimum functionality to meet immediate performance requirements,
are also described.
The repair processes specified are applicable to all installation environments except optical ground wires
(OPGW) or optical phase conductors (OPPC).
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.
EN 60794 (all parts), Optical fibre cables
3 Terms and definitions and abbreviations
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1.1
cable segment
length of cable between two existing closures which enable its final repair by its substitution
3.1.2
conduit
cabling cable management system of general circular cross-section used to contain and protect all types of
cables and microduct/microduct assemblies
3.1.3
final repair
repair process which restores pre-damaged performance and maintains pathway system capacity
3.1.4
interim repair
re-routing of the service using existing optical fibres in other cables or by the replacement of a length of
damaged cable with additional closures and joints (see Note) subject to the capability of the application-
specific equipment to support operation of the modified transmission path
Note 1 to entry: Not recommended due to additional splice losses and extra lengths.
3.1.5
microduct
tube, a sub-set of a cable management system, which is directly associated with a particular cabling
installation
3.1.6
microduct segment
length of microduct between two existing accessible microduct joints which allow its final repair by its
substitution of the modified channel
3.1.7
partial repair
repair process which restores pre-damaged mechanical performance by a localized repair but potentially
degrades the transmission performance and/or reliability of the testable segment
3.1.8
pre-damaged performance
the mechanical performance of the damaged components and their transmission performance within a
testable segment when they were a) as installed or b) as specified or c) last available test results or d) as
originally planned
3.1.9
strain-free damage
damage to an optical fibre cable (including the optical fibre) or microduct which is not associated with
elongation or where any elongation is localised at the point of damage
3.1.10
strain-related damage
permanent alteration of the construction elements of an optical fibre cable (including the optical fibre) or
microduct following the application of tensile loads or bending radii that are not in accordance with the limits
specified by the manufacturer of the optical fibre cable or microduct
3.1.11
testable segment
cabling between two adjacent cabling test interfaces, including all interim cables and joints
3.1.12
transmission path
passive cabling components between transmission equipment and which may contain multiple testable
segments
3.2 Abbreviations
For the purposes of this document, the following abbreviations apply.
OTDR optical time domain reflectometer
PA polyacrylate
PE polyethylene
PMD polarization mode dispersion
PP polypropylene
OPGW optical ground wire
OPPC optical phase conductor
4 Optical fibre cable network
4.1 General
Within the cabling installations addressed by this Technical Specification, the cables and/or microducts are
installed between closures and microduct joints respectively.
Figure 1 is a schematic of the key concepts outlined in this subclause.

Figure 1 — Schematic of cabling and microduct structures
For installations outside buildings, closures and accessible microduct joints are accommodated in
maintenance chambers or other structures (such as street cabinets in access networks). For installations
inside buildings, closures and accessible microduct joints are accommodated in boxes, cabinets, frames and
racks.
Testable optical interfaces are normally accommodated in cabinets, frames and racks within buildings or
other structures (such as street cabinets in access networks).
4.2 Optical fibre cable
4.2.1 General
Cables and microducts in accordance with EN 60794 series standards deliver long-term stability in terms of
mechanical and optical transmission properties provided that the installation and operational environments
have been correctly assessed during the cable selection process.
Clauses 4.2.2 to 4.2.4 provide explanatory descriptions of various cable and microduct construction concepts.
4.2.2 Loose buffer tube cable
4.2.2.1 General
Central loose tube as well as stranded loose tube optical fibre cables are the mostly installed cable types.
The cable jacket might consist of several layers containing different thermoplastic materials (e.g. polyethylene
(PE), polypropylene (PP), and polyacrylate (PA)), metallic armouring (e.g. corrugated steel tape, Al tape) as
well as non-metallic armouring (e.g. glass yarns). This Technical Specification gives advice and rules to the
cable operators and installers for the determination of the scope/extent and impact of damage to optical fibre
cables/optical fibre cable systems due to cable damage and determines appropriate repair work carried out.
4.2.2.2 Central and stranded loose buffer tube cable
Optical fibre cables are made of one un-stranded buffer tube (see Figure 2 and Figure 3) and, or around, a
central strength member - in one and/or multilayer stranded buffer tubes containing a number of fibres (1 ≤ n
optical fibres/ buffer tubes ≤ 96) (see Figure 4 and Figure 5).

Figure 2 — Example of central loose buffer tube cable

Figure 3 — Example cross-section of a central loose buffer tube cable

Figure 4 — Example of stranded loose buffer tube cable
Figure 5 — Example cross-section of stranded loose buffer tube cable
4.2.3 Microduct optical fibre cables for blowing
Small microduct cables are available containing up to 216 optical fibres which are blown into microducts. This
technique can also be used to replace traditional cable techniques and to concentrate fibres for several
subscribers in the network. One specific requirement for microduct optical fibre cables is to use the specified
type and dimensions to secure a standardized development of the network.

Figure 6 — Microduct with blown microduct optical cable
4.2.4 Dimensions for microducts and multi-duct bundles
Figure 7 shows examples of different designs of microducts and multi-duct bundles units for the use of optical
fibre microcables and/or blown fibre units.
Examples of microducts suitable for installation of microduct optical fibre cables and in combination with
conventional ducts are given in Annex B.
Figure 7 — Examples of microducts/microduct bundles
4.2.5 Optical fibre
Figure 8 shows a schematic of a silica optical fibre.

Figure 8 — Schematic of silica optical fibre structure
4.3 Types of installation of optical fibre cables
4.3.1 General
Effective specification of an installation requires that the cables shall be selected to be compatible with both
the intended pathways and pathway systems to be used and also with the installation and operational
environments. European Standards for optical fibre cables exist for different installation environments.
The maintenance of transmission performance of optical fibre cables relies on the protection that the cable
construction (tensile strength, crush resistance and resistance to ingress by contaminant liquids) provides to
the optical fibres.
4.3.2 Installation by direct burial
Direct burial cables are installed in stone-free soil and/or by laying the cable in a sand-filled cable trench. The
filled cable trench provides protection against damage from rocks and from the load of the overlying
ground/filling providing the best possible conditions for the cable.
The depth for direct burial is critical to ensure that the installation is not sacrificial. Requirements are given by
local, national or regional regulations/recommendations.
4.3.3 Installation in conduits
Cables and microducts designed for conduit installation are intended to provide appropriate protection.
Conduits may contain smaller sub-units.
Optical fibre cable can be installed by pulling in or by feeding in with compressed gases and/or liquids.
The depth of conduit burial is critical to ensure that the installation is not sacrificial. Requirements are given
by local, national or regional regulations/recommendations.
NOTE Several micro-tubes can be placed into the empty tube/conduit, in which the actual cable can be pulled or
blown in.
4.3.4 Installation in troughs
Cables and/or microducts are installed in troughs which are covered by cable bricks.
4.3.5 Installation in building
Within buildings, a variety of installation solutions are used including cable management systems such as
trays, trunking and conduits. Conduits are typically installed where cables enter building at or below ground
level.
5 Summary of damage and repair solutions
Once installed, there is always the probability of the operational environment undergoing a change which
subjects the cable to conditions which lie outside its specification.
Such changes include disruption to the pathway or pathway system within which the cable is installed which
subject the cable to mechanical or chemical stresses which reduce the protection provided by the cable
construction.
The Damage–Repair Matrix of Table 1 provides a short overview on interim and final repairs (needing
planning and coordination prior to it) by reference to the subclauses of this Technical Specification.
Table 1 — Damage-Repair Matrix
Damage Final repair Interim solution
Type Object Impact Cl. Process Cl. Process Cl.
Replace
Deformation microduct 8.3.3 None required -
segment
Partial repair -
Microduct
Replace protection
Cuts through* microduct 8.3.3 against ingress 8.2.6
segment of
contamination
Apply axial
Cuts in 8.3.1 None required -
closure
Cable outer
Partial repair -
sh
...