IEC 60794-2-50:2008

IEC 60794-2-50
Edition 1.0 2008-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Optical fibre cables –
Part 2-50: Indoor cables – Family specification for simplex and duplex cables for
use in terminated cable assemblies

Câbles à fibres optiques –
Partie 2-50: Câbles intérieurs – Spécification de famille pour les câbles simplex
et duplex utilisés dans les ensembles de câbles équipés

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IEC 60794-2-50
Edition 1.0 2008-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Optical fibre cables –
Part 2-50: Indoor cables – Family specification for simplex and duplex cables for
use in terminated cable assemblies

Câbles à fibres optiques –
Partie 2-50: Câbles intérieurs – Spécification de famille pour les câbles simplex
et duplex utilisés dans les ensembles de câbles équipés

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
V
CODE PRIX
ICS 33.180.10 ISBN 2-8318-9902-8
– 2 – 60794-2-50 © IEC:2008
CONTENTS
FOREWORD.4

1 Scope.6

2 Normative references .6

3 Terms and definitions .7

4 Construction .7

4.1 General .7

4.2 Optical fibres and primary coating .7

4.3 Buffer .7
4.4 Tube.8
4.5 Strength and anti-buckling members .8
4.6 Sheath .8
4.7 Sheath marking .8
4.8 Examples of cable constructions .8
5 Tests .8
5.1 Dimensions .9
5.2 Mechanical requirements.9
5.2.1 Tensile performance.9
5.2.2 Crush .9
5.2.3 Impact .10
5.2.4 Repeated bending .10
5.2.5 Bend.10
5.2.6 Torsion .11
5.2.7 Bend at low temperature.11
5.2.8 Kink.11
5.2.9 Sheath pull-off force .11
5.2.10 Buffered fibre movement in compression .12
5.3 Environmental requirements .12
5.3.1 Temperature cycling .12
5.3.2 Sheath shrinkage.13
5.4 Transmission requirements .13
5.5 Fire performance.13
Annex A (informative) Examples of some types of cable construction .14

Annex B (normative) METHOD E21 – Sheath pull-off force for optical fibre cable for
use in patch cords .17
Annex C (normative) METHOD F11 – Sheath shrinkage for optical fibre cable for use
in patchcords .22
Annex D (normative) METHOD E22 – Buffered fibre movement under compression in
optical fibre cables for use in patchcords .24
Annex E (normative) METHOD F12 – Temperature cycling for optical fibre cable for
use in patchcords .26
Annex F (normative) Guidance on the selection of tests applicable to optical fibre
cables for use in patchcords .28
Bibliography.

Figure A.1 – Simplex loose non-buffered fibre cable .14

60794-2-50 © IEC:2008 – 3 –
Figure A.2 – Simplex ruggedized fibre cable .14

Figure A.3 – Duplex loose non-buffered fibre cable.14

Figure A.4 – Duplex ruggedized fibre cable.15

Figure A.5 – Duplex ruggedized fibre zip cord.15

Figure A.6 – Duplex ruggedized flat cable.15

Figure A.7 – Duplex ruggedized round cable.16

Figure B.1 – Schematic of test arrangement .19

Figure B.2 – Example of pulling jig.20

Figure B.3 – Cable sample preparation .21
Figure D.1 – Test set up for fibre movement under compression.25

Table 1 – Dimensions of buffered fibres.8
Table 2 – Temperature cycling severities .12
Table F.1 – Cable test method summary.28
Table F.2 – Cable testing agreement .30

– 4 – 60794-2-50 © IEC:2008
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
OPTICAL FIBRE CABLES –
Part 2-50: Indoor cables –
Family specification for simplex and duplex cables

for use in terminated cable assemblies

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,
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with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
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6) All users should ensure that they have the latest edition of this publication.
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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 60794-2-50 has been prepared by subcommittee 86A: Fibres and
cables, of IEC technical committee 86: Fibre optics.
This standard cancels and replaces IEC/PAS 60794-2-50 published in 2004. This first edition
constitutes a technical revision.
This standard is to be used in conjunction with IEC 60794-1-1, IEC 60794-1-2 and
IEC 60794-2.
This bilingual version, published in 2008-07, corresponds to the English version.

60794-2-50 © IEC:2008 – 5 –
The text of this standard is based on the following documents:

FDIS Report on voting
86A/1204/FDIS 86A/1223/RVD
Full information on the voting for the approval of this standard can be found in the report on

voting indicated in the above table.

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, 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.
– 6 – 60794-2-50 © IEC:2008
OPTICAL FIBRE CABLES –
Part 2-50: Indoor cables –
Family specification for simplex and duplex cables

for use in terminated cable assemblies

1 Scope
This part of IEC 60794 is a family specification that covers requirements for simplex and
duplex optical fibre cables for use in terminated cable assemblies or for termination with
optical fibre passive components.
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 and IEC 60794-1-2) or in the sectional specification (IEC 60794-2 series).
IEC 60068-2-14, Environmental testing – Part 2: Tests. Test N: Change of temperature
IEC 60189-1, Low-frequency cables and wires with PVC insulation and PVC sheath – Part 1:
General test and measuring methods
IEC 60793-1-1:2008, Optical fibres – Part 1-1: Measurement methods and test procedures –
General and guidance
IEC 60793-1-20, Optical fibres – Part 1-20: Measurement methods and test procedures –
Fibre geometry
IEC 60793-1-21, Optical fibres – Part 1-21: Measurement methods and test procedures –
Coating geometry
IEC 60793-1-40, Optical fibres – Part 1-40: Measurement methods and test procedures –

Attenuation
IEC 60793-1-46, Optical fibres – Part 1-46: Measurement methods and test procedures –
Monitoring of changes in optical transmittance
IEC 60793-2-10, Optical fibres – Part 2-10: Product specifications – Sectional specification for
category A1 multimode fibres
IEC 60793-2-50, Optical fibres – Part 2-50: Product specifications – Sectional specification for
class B single-mode fibres
IEC 60794-1-1, Optical fibre cables – Part 1-1: Generic specification – General
IEC 60794-1-2:2003, Optical fibre cables – Part 1-2: Generic specification – Basic optical
cable test procedures
60794-2-50 © IEC:2008 – 7 –
IEC 60794-2, Optical fibre cables – Part 2: Indoor cables – Sectional specification

IEC 60811-1-3, Common test methods for insulating and sheathing materials of electric and

optical cables – Part 1-3: General application – Methods for determining the density – Water

absorption tests – Shrinkage test

IEC 60811-1-4:1985, Common test methods for insulating and sheathing materials of electric

cables – Part 1: Methods for general application – Section Four: Tests at low temperature

Amendment 1 (1993)
Amendment 2 (2001)
ISO/IEC 11801, Information technology – Generic cabling for customer premises
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
terminated cable assembly
short length of cable provisioned with a connector at both ends
NOTE Examples from ISO/IEC 11801 are:
Patchcords are used to establish connections on a patch panel. Typical length of the patchcord 1 m to 10 m.
Work area cords are used to connect outlet to the terminal equipment. Typical length of the work area cords
according to this specification is between 1 m and 35 m.
Equipment cords should fulfill the requirements of patchcords or work area cords depending on their application.
4 Construction
4.1 General
In addition to the constructional requirements in IEC 60794-2, the following considerations
apply to simplex and duplex indoor cables for use in terminated cable assemblies.
It is not the intention of this standard to specify the finished terminated cable assembly
complete with terminations.
The cable shall be designed and manufactured for an expected operating lifetime of 15 years.
The materials in the cable shall not present a health hazard within its intended use.

There shall be no fibre splice in a delivery length. It shall be possible to identify each
individual fibre throughout the length of the cable.
4.2 Optical fibres and primary coating
Multimode or single-mode optical fibres meeting the requirements of IEC 60793-2-10, type
A1a and A1b, and IEC 60793-2-50, type B, shall be used.
4.3 Buffer
If a tight or semi-tight (loosely applied) buffer is required, it shall consist of one or more layers
of inert material. Semi-tight tubes may be filled. Unless otherwise specified, the buffer shall
be removable in one operation over a length of 15 mm.
Buffer dimensions are shown in Table 1.

– 8 – 60794-2-50 © IEC:2008
Table 1 – Dimensions of buffered fibres

Nominal diameter (mm) 0,3 – 1,3

Tolerances (mm) ± 0,05
4.4 Tube
One or two primary coated or buffered fibres are packaged (loosely or not) in a tube

construction which may be filled. The tube may be reinforced with a composite wall.

If required the suitability of the tube shall be determined by an evaluation of its kink

resistance in accordance with IEC 60794-1-2, Method G7.
4.5 Strength and anti-buckling members
The cable shall be designed with sufficient strength members to meet the requirements of this
standard.
The strength and/or anti-buckling member 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.
4.6 Sheath
The cable shall have a uniform overall protective sheath. The cable diameter shall be
specified in the relevant detail specification (or product specification). Sheath removal is an
important feature of these cables. This is tested by the method E21 described in Annex B of
this standard.
4.7 Sheath marking
If required, the cable shall be marked as agreed between the customer and supplier. The
marking shall be resistant to abrasion.
4.8 Examples of cable constructions
Examples of some main types of cable construction are shown in Figures A.1 to A.7.
Other configurations are not excluded if they meet the mechanical, environmental,
transmission and termination requirements given in this standard.
5 Tests
Compliance with the specification requirements shall be verified by carrying out tests selected
from the following subclauses. It is not intended that all tests be carried out in all cases, and
Annex F provides guidance on the selection of tests. The tests to be applied and the
frequency of testing shall be agreed between the customer and supplier.
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 making it possible to detect permanent changes in
attenuation.
60794-2-50 © IEC:2008 – 9 –
)
Single-mode cables shall be measured at 1 550 nm and 1 625 nm and multimode cables

shall be measured at 1 300 nm unless otherwise agreed. Measurements shall be carried out

according to IEC 60793-1-40.
If loops are used within a test to fix the ends of a cable, the diameter shall not be so small as

to cause excessive mode filtering in multimode fibre.

Unless otherwise specified, all tests shall be carried out at ambient temperature, as described

in IEC 60793-1-1, Clause 5.
5.1 Dimensions
The fibre dimensions and tolerances shall be checked in accordance with test method of
IEC 60793-1-20 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.
5.2 Mechanical requirements
5.2.1 Tensile performance
Method: IEC 60794-1-2-E1A.
Diameter of chuck drums and transfer devices: not less than the minimum dynamic bending
diameter specified for the cable, at least 250 mm diameter.
Rate of transfer device: either 100 mm/min or 100 N/min.
Load: 100 N applied for 5 min for simplex cables, 200 N for 5 min for duplex cables.
Length of sample: sufficient to achieve the desired accuracy of measurement of attenuation
change and shall be agreed between the customer and the supplier.
Requirements: the maximum increase in attenuation during the test shall be specified in the
product specification, there shall be no change in attenuation after the test, and there shall be
no damage to the cable elements.
5.2.2 Crush
Method: IEC 60794-1-2-E3.
Force: 500 N.
Duration: 1 min.
Length between test locations: 500 mm.
Requirements: the maximum increase in attenuation during the test shall be specified in the
product specification, there shall be no change in attenuation after the test, and there shall be
no damage to the cable elements.
NOTE For cables having a non-circular cross section, the force should be applied in the direction of the minor
axis (perpendicular to the major axis).
___________
)
OM3 multimode cables should be tested at 850 nm and may be tested at 1 300 in addition, all other
multimode cables should be tested at 1 300 nm.

– 10 – 60794-2-50 © IEC:2008
5.2.3 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 at least 500 mm.

Requirements: the maximum increase in attenuation after the test shall be specified in the

product specification and there shall be no fibre breakage or damage to the cable elements.
Any imprint of the striking surface on the cable sheath is not considered as a mechanical
damage.
NOTE For cables having a non-circular cross section, the force should be applied in the direction of the minor
axis (perpendicular to the major axis).
5.2.4 Repeated bending
Method: IEC 60794-1-2-E6.
Bending radius: 30 mm for simplex, 20 times cable diameter for duplex (for non-circular
cables, the cable diameter is the minor dimension).
Number of cycles: 200.
Mass of weights: sufficient to contour the apparatus e.g. 1 kg to 2 kg.
Requirements: the maximum increase in attenuation during the test shall be specified in the
product specification, there shall be no change in attenuation after the test, and there shall be
no damage to the cable elements.
NOTE For cables having a non-circular cross section, the bend requirements are determined using the minor axis
as the cable diameter with bending in the direction of the preferential bend.
5.2.5 Bend
Method: IEC 60794-1-2-E11A.
Mandrel diameter: 60 mm.
Number of turns per helix: 6.
Number of cycles: 3.
Length of sample: sufficient to carry out the test.
Prior to bending: at both ends of the sample all the cable components shall be fixed together,
e.g. by loops or glue.
Requirements: the maximum increase in attenuation during the test shall be specified in the
product specification, there shall be no change in attenuation after the test, and there shall be
no damage to the cable elements.
NOTE For cables having a non-circular cross section, the bend requirements are determined using the minor axis
as the cable diameter with bending in the direction of the preferential bend.

60794-2-50 © IEC:2008 – 11 –
5.2.6 Torsion
Method: IEC 60794-1-2-E7.
Number of cycles: 10.
Distance between fixed and rotating clamps: 250 mm.

Tension load: according to Table 1 of IEC 60794-1-2-E7.

Length of sample: sufficient to carry out the test.

Requirements: the maximum increase in attenuation during the test shall be specified in the
product specification, there shall be no change in attenuation after the test, and there shall be
no damage to the cable elements.
5.2.7 Bend at low temperature
Method: IEC 60794-1-2-E11A (see IEC 60811-1-4, Clause 8)
Bending radius: 10 times cable diameter (for non-circular cables, the cable diameter is the
minor dimension) but not less than 30 mm.
Number of cycles: 2.
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.
Requirements: in addition to the requirement of Clause 8 of IEC 60811-1-4, no fibre shall
break during the test and there shall be no damage to the cable elements.
5.2.8 Kink
Method: IEC 60794-1-2-E10.
Minimum loop, horizontal inner dimension: (for non-circular cables, the cable diameter is the
minor dimension), see Figure E.10.
– For cables outer diameter ≤ 3,0 mm, to be 10 mm.
– For cables outer diameter > 3,0 mm, to be 5 × the cable diameter.
NOTE This is not an operational parameter; this is to address short-term installation/handling performance.
Requirement: no kink shall occur.
5.2.9 Sheath pull-off force
Method: see Annex B.
Rate of separation: ≤ 200 mm/min.
Strip length: 50 mm.
Requirement: the force to strip the sheath shall not be greater than 15 N.

– 12 – 60794-2-50 © IEC:2008
5.2.10 Buffered fibre movement in compression

Method: See Annex D.
Compression distance: 1 mm.
Number of movements: 5.
Requirement: the maximum increase in attenuation during the test shall be specified in the

product specification and the reaction force shall be less than 1 N at 0,4 mm.

5.3 Environmental requirements
5.3.1 Temperature cycling
Method: See Annex E.
Severity taken from Table 2 below.
Period: t sufficient that the cable has reached, and stabilised to, the specified temperature.
Number of cycles: 4.
Length of sample: 10 m.
Requirements: maximum increase in attenuation shall be as shown in Table 2 below.
Measurement uncertainty:
– 0,05 dB for cables with single-mode fibres;
– 0,10 dB for cables with multimode fibres.
Table 2 – Temperature cycling severities
Low High Maximum increase in Maximum increase in Maximum increase in
temperature temperature attenuation at attenuation at attenuation at
T T 1 300 nm 1 550 nm 1 625 nm
A B
dB dB dB
°C °C
a) 0 +50 0,1 0,1 0,2
b) –5 +50 0,1 0,2 0,3
c) –20 +60 0,3 0,5 1,0
d) –45 +60 0,3 0,5 1,0
e) –25 +70 0,3 0,5 1,0
f) –40 +85 0,3 0,5 1,0
NOTE Condition a), b), c), d) e) or f) should be selected depending on application and user requirements, for
example condition c) is appropriate for applications to ISO/IEC 11801. The low temperature requirement for the
completed patchcord assembly is –10 °C.

60794-2-50 © IEC:2008 – 13 –
5.3.2 Sheath shrinkage
Method: see Annex C.
Exposure temperature: 70 °C.
Exposure duration: 24 hours per cycle.

Number of cycles: 4.
Requirement: the average of the sheath shrinkage values shall not exceed 20 mm.
5.4 Transmission requirements
The transmission requirements shall be verified in accordance with IEC 60794-1-2 and shall
be agreed between customer and supplier. Maximum cable attenuation shall comply with
IEC 60794-1-1.
5.5 Fire performance
IEC/TR 62222 provides guidance and recommendations for the requirements and test
methods for the fire performance of communication cables when installed in buildings. The
recommendations relate to typical applications and installation practices, and an assessment
of the fire hazards presented. Account is also taken of applicable legislation and regulation.
IEC/TR 62222 references several IEC fire performance test methods and also other test
methods that may be required by local or National legislation and regulation. The tests to be
applied, and the requirements, shall be agreed between the customer and supplier taking into
account the fire hazard presented by the end use application of the terminated cable
assembly in which the cable is intended to be used.

– 14 – 60794-2-50 © IEC:2008
Annex A
(informative)
Examples of some types of cable construction

NOTE The main dimensions should be agreed between the customer and the supplier.

Sheath
Strength member embedded
in the sheath
Primary-coated optical fibre
IEC  445/08
Figure A.1 – Simplex loose non-buffered fibre cable

Sheath
Strength member
Buffer
Primary coating
Fibre
IEC  446/08
Figure A.2 – Simplex ruggedized fibre cable

Sheath
Strength member embedded
in the sheath
Primary-coated optical fibre
IEC  447/08
Figure A.3 – Duplex loose non-buffered fibre cable

60794-2-50 © IEC:2008 – 15 –
Sheath
Strength member
Buffer
Primary coating
Fibre
IEC  448/08
Figure A.4 – Duplex ruggedized fibre cable

Sheath
Strength member
Buffer
Primary coating
Fibre
IEC  449/08
Figure A.5 – Duplex ruggedized fibre zip cord

Strength member
Optional strength member
Primary coated
optical fibre
Buffer
Sheath
Common sheath
IEC  450/08
Figure A.6 – Duplex ruggedized flat cable

– 16 – 60794-2-50 © IEC:2008
Primary coated
optical fibre
Buffer
Strength member
Sheath
Common sheath
Filler (optional)
IEC  451/08
Figure A.7 – Duplex ruggedized round cable

60794-2-50 © IEC:2008 – 17 –
Annex B
(normative)
METHOD E21 –
Sheath pull-off force for optical fibre cable for use in patch cords

B.1 Object
The purpose of this test is to measure the force required to remove a length of sheath from an

optical fibre cable intended for use in patchcords.
B.2 General
This test method is designed to measure the force required to remove the cable sheath. It can
be applied to round simplex and round duplex optical fibre cables for use in patchcords, or
round single fibre elements or sub-elements of larger cables.
B.3 Sample
A length of cable long enough to be retained in the tensile rig shall be cut and removed from
the supply reel. The sample is prepared as shown in Figure B.3, using the following method.
At one end of the sample, mark the cable at distances 50 mm and 53 mm from the end. A
circumferential cut is then made at the two marked points where the section of sheath is to be
removed. A longitudinal cut is then made between the two circumferential cuts. Remove the
sheathing between the two cuts. During sample preparation, if any damage is imparted to the
cable core, that sample shall be discarded.
B.4 Apparatus
A schematic of the test arrangement is shown in Figure B.1.
B.4.1 Tensile test rig
A controllable tensile facility shall be used with the ability to pull over a specified distance at a
controlled speed.
B.4.2 Recording equipment
A set of measurement equipment shall be used, linked to the tensile test rig that can record
the forces required to remove the sheath from the cable core. Measurements shall be
recorded in newtons.
B.4.3 Stripping tools
Tools capable of removing at least a 3 mm length of outer sheath at a distance 50 mm from
the end of the cable, leaving the cable core undamaged, may be used.
B.4.4 Pulling jig
A pulling jig as shown in Figure B.2 shall be designed to fit into the gap formed in the sample
sheath by removing the 3 mm section, allowing the 50 mm strip length of sheath to be pulled
longitudinally from the prepared end of the cable.

– 18 – 60794-2-50 © IEC:2008
B.4.5 Cable anchor
A method shall be provided to secure the anchor end of the cable while the pull is carried out.

B.5 Procedure
The prepared end of the cable is inserted into the pulling jig (see Figure B.1) mounted on the

test rig. The opposite end of the sample is then mounted in the cable anchor at zero load. A

controlled pull is then carried out at the specified speed. Readings are taken to record the

peak values of each test pull.

B.6 Requirements
The force required to remove the sheath from the cable core shall comply with the values
given in the detail specification.
B.7 Details to be specified
The detail specification shall include:
a) rate of separation (speed of pull);
b) strip length (length of sheath removed);
c) force to strip the length of sheath.

60794-2-50 © IEC:2008 – 19 –
Direction of pull
Anchor end of cable
IEC  577/08
Figure B.1 – Schematic of test arrangement

– 20 – 60794-2-50 © IEC:2008
Dimensions in millimetres
20 20
2,5 ∅5
Dimensions and design of the securing
end of this tool can be modified to
suit the type of pulling rig used
IEC  578/08
Figure B.2 – Example of pulling jig

1,4 slot
∅6
∅13
∅16
60794-2-50 © IEC:2008 – 21 –
50 mm
Strip length
3 mm gap
This length to suit
retaining set up
IEC  579/08
Figure B.3 – Cable sample preparation

– 22 – 60794-2-50 © IEC:2008
Annex C
(normative)
METHOD F11 –
Sheath shrinkage for optical fibre cable for use in patchcords

C.1 Object
The purpose of this test is to measure the shrinkage behaviour of the sheath due to ageing of

simplex and duplex optical fibre cables intended for use in patchcords.

C.2 General
This test method is based on IEC 60811-1-3 with modifications related to the sampling and
measuring method.
C.3 Apparatus
A container (with typical dimensions 0,5 m × 0,5 m) into which the test sample is placed. The
base of the container shall be covered with talc or paper to minimise frictional forces on the
test sample and to permit free movement of the sheath.
A temperature chamber able to accommodate the test sample container, and maintain the
specified temperature within ± 3 ºC as described in IEC 60068-2-14, Method Nb.
A length measuring device with a minimum resolution of 0,5 mm.
C.4 Conditioning
The cable on the supply reel shall be conditioned for 24 h at a room temperature of 23 ± 5 °C
before cutting the test samples.
C.5 Sampling
A 2 m length of cable shall be removed from the supply reel and disposed, before cutting the
test sample lengths. Five test samples each with a length of 1 050 mm ± 5 mm shall be cut
from the cable.
C.6 Procedure
Two marks separated by a distance of 1 000 mm ± 0,5 mm shall be applied to each test
sample. The marks shall be located at approximately 25 mm from each end of the test
sample.
The distance (L ) between the sheath marks on each test sample shall be measured and
recorded. The test samples shall be coiled with a radius of not less than 150 mm and in such
a manner as to permit free movement of the sheath. A test sample coil is then placed
approximately horizontally in the container.
The temperature chamber shall be heated up to the specified temperature.
The container with horizontally positioned samples is then placed in the temperature chamber.

60794-2-50 © IEC:2008 – 23 –
After the specified heating time, the container with samples shall be removed from the

chamber and allowed to cool to room temperature.

Four such cycles shall be carried out.

After four cycles, the distance (L ) between the sheath marks on each test sample shall be
measured and recorded.
The sheath shrinkage of each test sample is calculated as:

ΔL = (L – L ) mm
x 1 2
where
L is the initial distance measured between the sheath marks;
L is the distance measured between the sheath marks after four cycles.
C.7 Requirements
The average sheath shrinkage of the five samples shall not exceed the value given in the
relevant specification.
C.8 Details to be specified
The detail specification shall include:
a) details of temperature chamber and exposure high temperature;
b) duration of exposure to high temperature;
c) number of samples;
d) method of sheath marking and length measurement;
e) sample configuration and fixing in the container;
f) number of cycles;
g) average sheath shrinkage.
– 24 – 60794-2-50 © IEC:2008
Annex D
(normative)
METHOD E22 –
Buffered fibre movement under compression in optical fibre

cables for use in patchcords
D.1 Object
The purpose of this test is to examine the attenuation behaviour (change in attenuation) and

the reaction force when a buffered fibre in a cable intended for use in patchcords moves
under axial compression only.
D.2 Apparatus
A device to fix one cable end without compression and a chuck to fix the buffered fibre
protruding from this cable end. The chuck shall be movable towards the cable end for an
adjustable distance (see Figure D.1). The fixed distance between the chuck and the cable end
shall be 7 mm.
Load cell for monitoring the force on the chuck with a maximum error of ± 3 %.
Attenuation monitoring equipment as described in IEC 60793-1-46.
D.3 Sampling
A 5 m long cable sample shall be taken from a finished cable length.
At both ends of the sample, 2 m of the cable sheath and other cable elements are removed,
leaving a central 1,0 m length of cable sheath on the sample.
D.4 Procedure
One end of the 1,0 m length of sheathed cable sample including the strength member is fixed
at one side in the cable fixing device (1 in Figure D.1) and the exposed buffered fibre is fixed
in the fibre chuck (2 in Figure D.1).

At the other end of the 1,0 m sample the fibre and the sheath are glued together by e.g. epoxy
to prevent any movement of the fibre within the cable sample.
The unsheathed fibres are connected to the attenuation monitoring equipment (see
Figure D.1).
The chuck is moved towards the fixed cable end for the required compression distance given
in the relevant detail specification.
During the movement, any attenuation change and the reaction force are monitored.
The test shall be carried out at ambient temperature.

60794-2-50 © IEC:2008 – 25 –
D.5 Requirement
Attenuation change and the reaction force at 0,4 mm displacement shall not exceed the

values given in the relevant specification.

D.6 Details to be specified
The detail specification shall include:

a) compression distance;
b) method of monitoring attenuation change;
c) number of movements;
d) reaction force;
e) change in attenuation.
1 000 mm
7 mm
Epoxy Cable
1 2
Buffered fibre
Buffered fibre
002 dB
Attenuation
monitoring
IEC  580/08
Key
1 Cable fixing
2 Fibre chuck and load cell
Compression movement
Figure D.1 – Test set up for fibre movement under compression

– 26 – 60794-2-50 © IEC:2008
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