IEC 60794-1-215:2020

Optical fibre cables – Part 1-215: Generic specification – Basic optical cable test procedures – Environmental test methods – Cable external freezing test, Method F15

IEC 60794-1-215:2020 defines test procedures to be used in establishing uniform requirements for the environmental performance of
- optical fibre cables for use with telecommunication equipment and devices employing similar techniques, and
- cables having a combination of both optical fibres and electrical conductors.
Throughout this document, the wording "optical cable" can also include optical fibre units, microduct fibre units, etc. This document defines a test standard to determine the ability of a cable to withstand the effects of freezing water that can immediately surround the optical fibre cable sheath by observing any changes in the physical appearance of the sheath, or in the measured cable optical attenuation. Method F15A is a test standard to simulate freezing of the medium surrounding a buried cable, as in wet earth or water. Method F15A is moved from method F15 in IEC 60794-1-22:2017 without any technical changes. Method F15B is a test standard to simulate freezing of the medium surrounding an outside cable in a rigid conduit (duct) which is made of rigid material, for example steel. Method F15B includes the solution to prevent the cable from being crushed when experiencing freezing conditions in a rigid conduit (duct) which are pressure absorber pads and any other suggested means of cable protection. A reference guide to test methods of all types as well as general requirements can be found in IEC 60794-1-2.

Câbles à fibres optiques - Partie 1-215: Spécification générique - Procédures fondamentales d'essais des câbles optiques - Méthodes d’essais d’environnement - Essai de résistance au gel en extérieur des câbles, méthode F15

IEC 60794-1-215:2020 définit les procédures d’essai à utiliser pour définir des exigences harmonisées pour les performances environnementales:
- des câbles à fibres optiques destinés à être utilisés avec les équipements et dispositifs de télécommunications employant des techniques similaires; et
- des câbles combinant fibres optiques et conducteurs électriques.
Dans le présent document, le terme « câble optique » peut également englober les unités de fibres optiques, les unités de fibres en microconduit, etc. Le présent document définit une norme d’essai pour déterminer la capacité d’un câble à résister aux effets de l’eau gelée pouvant se situer au voisinage immédiat de la gaine d’un câble à fibres optiques, en observant les quelconques variations d’aspect physique de la gaine, ou les quelconques variations de l’affaiblissement mesuré sur le câble. La méthode F15A est une norme d’essai pour simuler le gel du milieu entourant un câble enfoui, par exemple de la terre humide ou de l’eau. La méthode F15A est déplacée de la méthode F15 de l’IEC 60794-1-22:2017 sans aucune modification technique. La méthode F15B est une norme d’essai pour simuler le gel du milieu entourant un câble extérieur dans un conduit (gaine) rigide fabriqué dans un matériau rigide, par exemple l’acier. La méthode F15B inclut la solution qui évite l’écrasement du câble lorsqu’il est soumis à des conditions de gel dans un conduit (gaine) rigide, qui consiste en des tampons d’absorption de la pression et les quelconques autres moyens de protection du câble suggérés. Un guide de référence répertoriant les méthodes d’essai de tous types, ainsi que les exigences générales, peut être consulté dans l’IEC 60794-1-2.

General Information

• Status: Published
• Publication Date: 25-Jun-2020
• ICS: 33.180.10 - Fibres and cables
• Technical Committee: SC 86A - Fibres and cables
• Current Stage: PPUB - Publication issued
• Start Date: 26-Jun-2020
• Completion Date: 31-Jul-2020

Overview

IEC 60794-1-215:2020 is an international standard developed by the International Electrotechnical Commission (IEC) that defines basic test procedures for optical fibre cables, specifically focusing on environmental test methods related to cable external freezing. This standard is essential for assessing the durability and environmental performance of optical fibre cables exposed to freezing conditions, ensuring their reliability in telecommunication and combined optical-electrical cable applications.

The document details two main test methods under the “F15” designation to simulate the effect of freezing water or media surrounding optical fibre cables:

• Method F15A: Tests freezing effects on buried cables in wet earth or water.
• Method F15B: Tests freezing conditions of cables installed within rigid conduits (ducts), such as steel pipes.

This standard provides uniform test procedures useful for manufacturers, designers, and quality assurance professionals involved in optical cable production and installation.

Key Topics

• Environmental Performance Testing
  The standard establishes procedures to evaluate how optical fibre cables withstand exposure to freezing water surrounding the cable sheath. This simulates real-world environmental conditions affecting underground or duct-embedded cables.

• Test Method F15A: Cable Freezing for Buried Cables

  • Simulates freezing in soil or water surrounding buried cables.
  • Focuses on detecting changes in the physical sheath appearance and optical attenuation.
  • Helps verify cable resilience to adverse temperature and moisture conditions.

• Test Method F15B: Cable Freezing in Rigid Conduits

  • Simulates freezing within rigid metallic or plastic conduits.
  • Includes provisions for pressure absorber pads to mitigate crushing risks when water expands upon freezing.
  • Addresses cable protection strategies for ducts prone to freeze-related mechanical stress.

• Measurement Criteria
  The tests monitor:

  • Physical alterations in the optical cable sheath.
  • Changes in optical attenuation or signal quality to ensure integrity under freezing stress.

• Scope of Application
  Covers optical fibre cables for telecommunication systems and hybrid cables combining optical fibres with electrical conductors. It also extends to optical fibre units and microduct fibre units.

• Reference Standards
  Relies on related IEC standards such as IEC 60793-1-46 (optical fibre measurement methods), IEC 60794-1-1 (generic specifications for optical cables), and IEC 60794-1-2 (general guidance on test methods).

Applications

The IEC 60794-1-215:2020 standard is highly relevant in scenarios where optical fibre cables are exposed to potentially freezing environments, including:

• Telecommunication Backbone and Access Networks
  Ensures cable reliability for buried and duct-installed fibre optic infrastructure in cold climates.

• Outdoor and Underground Cable Installations
  Assesses cable performance when subjected to freeze-thaw cycles in soil or water-saturated conditions.

• Hybrid Cable Systems
  Evaluates the environmental robustness of cables combining optical fibres with electrical conductors, critical for power-over-fibre or utility communications.

• Cable Manufacturing and Quality Control
  Serves as a standardized test for manufacturers to certify optical cable resistance to freezing and associated mechanical stress.

• Infrastructure Planning
  Assists engineers and designers in selecting cables suitable for installation in regions with severe winters or in environments susceptible to freeze-related damage.

Related Standards

For a comprehensive understanding and implementation of optical fibre cable testing, the following IEC standards are closely connected with IEC 60794-1-215:

• IEC 60794-1-1: Provides generic specifications and terms relating to optical fibre cables.
• IEC 60794-1-2: Offers broad test procedure guidance applicable across optical cable testing methods.
• IEC 60794-1-22:2017: Contains other environmental test methods including the original Method F15, from which F15A is derived.
• IEC 60793-1-46: Defines measurement methods for monitoring changes in optical fibre transmittance, vital for assessing attenuation during freezing tests.
• ITU-T L.108:2018 (Related recommendation): Offers guidance on microduct cables and may be referenced when considering freezing tests for such units.

---

Keywords: IEC 60794-1-215, optical fibre cables, cable external freezing test, environmental test methods, Method F15, Method F15A, Method F15B, optical cable testing, telecommunication cables, cable freezing resistance, optical attenuation, rigid conduit cables, buried optical fibre cables, optical fibre cable standards, IEC standards for optical cables.

Standards Content (Sample)

IEC 60794-1-215 ®
Edition 1.0 2020-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Optical fibre cables –
Part 1-215: Generic specification – Basic optical cable test procedures –
Environmental test methods – Cable external freezing test, Method F15

Câbles à fibres optiques –
Partie 1-215: Spécification générique – Procédures fondamentales d’essais des
câbles optiques – Méthodes d’essais d’environnement – Essai de résistance au
gel en extérieur des câbles, méthode F15

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IEC 60794-1-215 ®
Edition 1.0 2020-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Optical fibre cables –
Part 1-215: Generic specification – Basic optical cable test procedures –

Environmental test methods – Cable external freezing test, Method F15

Câbles à fibres optiques –
Partie 1-215: Spécification générique – Procédures fondamentales d’essais des

câbles optiques – Méthodes d’essais d’environnement – Essai de résistance au

gel en extérieur des câbles, méthode F15

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.180.10 ISBN 978-2-8322-8570-1

– 2 – IEC 60794-1-215:2020 © IEC 2020
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Method F15A – Cable external freezing test for a buried cable as in wet earth or
water . 7
4.1 Object . 7
4.2 Sample . 7
4.3 Apparatus . 7
4.4 Procedure . 8
4.5 Requirements . 8
4.6 Details to be specified . 8
5 Method F15B – Cable external freezing test in a rigid conduit (duct) . 8
5.1 Object . 8
5.2 Sample . 8
5.3 Apparatus . 9
5.4 Procedure . 9
5.5 Requirements . 10
5.6 Details to be specified . 10
Annex A (informative) Example of freezing pressure absorber elements . 11
Bibliography . 13

Figure 1 – Example of F15B apparatus of cable external freezing test in a rigid conduit . 9
Figure A.1 – Example of freezing pressure absorber elements . 11
Figure A.2 – Cross section of the rigid conduit with an optical cable and freezing
pressure absorber elements when the water freezing . 12

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
OPTICAL FIBRE CABLES –
Part 1-215: Generic specification –
Basic optical cable test procedures –
Environmental test methods –
Cable external freezing test, Method F15

FOREWORD
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rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60794-1-215 has been prepared by subcommittee 86A: Fibres and
cables, of IEC technical committee 86: Fibre optics.
The text of this International Standard is based on the following documents:
FDIS Report on voting
86A/2008/FDIS 86A/2026/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.

– 4 – IEC 60794-1-215:2020 © IEC 2020
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.

INTRODUCTION
This part of IEC 60794 defines a test method to determine the ability of a cable to withstand the
effects of freezing water that can immediately surround the optical fibre cable sheath by
observing any changes in the physical appearance of the sheath, or in the measured cable
optical attenuation. The cable external freezing test in a rigid conduit (duct) is an item of F15
under consideration in IEC 60794-1-22:2017.
This document includes method F15 of IEC 60794-1-22:2017 as F15A: Cable external freezing
test for a buried cable, as in wet earth or water. There is no technical change in F15A. F15B is
a new introduced method. The numbering of these tests continues the F-series numbering
sequence of IEC 60794-1-22:2017.
The number of IEC 60794-1-215 is in line with the new numbering system of test methods as
planned in IEC 60794-1-2 .
___________
Fifth edition under preparation. Stage at the time of publication: IEC/CC 60794-1-2:2020.

– 6 – IEC 60794-1-215:2020 © IEC 2020
OPTICAL FIBRE CABLES –
Part 1-215: Generic specification –
Basic optical cable test procedures –
Environmental test methods –
Cable external freezing test, Method F15

1 Scope
This part of IEC 60794-1 defines test procedures to be used in establishing uniform
requirements for the environmental performance of
• optical fibre cables for use with telecommunication equipment and devices employing similar
techniques, and
• cables having a combination of both optical fibres and electrical conductors.
Throughout this document, the wording "optical cable" can also include optical fibre units,
microduct fibre units, etc.
This document defines a test standard to determine the ability of a cable to withstand the effects
of freezing water that can immediately surround the optical fibre cable sheath by observing any
changes in the physical appearance of the sheath, or in the measured cable optical attenuation.
Method F15A is a test standard to simulate freezing of the medium surrounding a buried cable,
as in wet earth or water. Method F15A is moved from method F15 in IEC 60794-1-22:2017
without any technical changes.
Method F15B is a test standard to simulate freezing of the medium surrounding an outside cable
in a rigid conduit (duct) which is made of rigid material, for example steel. Method F15B includes
the solution to prevent the cable from being crushed when experiencing freezing conditions in
a rigid conduit (duct) which are pressure absorber pads and any other suggested means of
cable protection.
A reference guide to test methods of all types as well as general requirements can be found in
IEC 60794-1-2.
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 60793-1-46, Optical fibres – Part 1-46: Measurement methods and test procedures –
Monitoring of changes in optical transmittance
IEC 60794-1-1, Optical fibre cables – Part 1-1: Generic specification – General
IEC 60794-1-2, Optical fibre cables – Part 1-2: Generic specification – Basic optical cable test
procedures – General guidance
3 Terms and definitions
For the purposes of this document, the terms and definitions 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
4 Method F15A – Cable external freezing test for a buried cable as in wet earth
or water
4.1 Object
This test determines the ability of a buried cable, as in wet earth or water, to withstand the
effects of freezing water that can immediately surround the optical fibre cable sheath by
observing any changes in the physical appearance of the sheath, or in the measured cable
optical attenuation.
The external freezing test simulates freezing of the medium surrounding a buried cable, as in
wet earth or water. It is not intended to simulate freezing of a cable in a rigid conduit (duct) or
pipe; refer to F15B for this testing. This external freezing test has little use for evaluating an
outdoor cable, since such cables rarely fail the test. The aggregate of other requirements for
outdoor cables results in a cable that is sufficiently robust to easily withstand this test. For
freezing of microduct cables in microducts, consideration of ITU-T L.108:2018, Appendix II, is
suggested [2] . It can be useful for evaluating cables not normally intended for outdoor
installation. Users are encouraged to refer to national standards in effect in applicable regions.
4.2 Sample
A 50 m minimum length of cable shall be loosely coiled in the water to be frozen. Contact
between the cable coil and the water tank wall shall be random. Additional length sufficient to
make the required optical measurements and to connect the cable from the apparatus to the
measuring equipment shall be provided.
4.3 Apparatus
The apparatus shall be a water tank suitable to contain the sample gauge length covered with
water.
The water shall be common tap water. This procedure is written in view of the use of tap water.
Other types of water, such as sea water or the like, shall be as specified by the detail
specification. In these cases, the detail specification can prescribe temperatures other than
those specified herein.
The water tank shall be positioned in an apparatus suitable for freezing the water and
maintaining it at the specified temperature ±3 °C. An environmental chamber is a common
example. Optionally, a temperature monitoring device may be used to monitor the cable
temperature. In this case, the device shall be in close proximity to the sample under test.
___________
Numbers in square brackets refer to the Bibliography.

– 8 – IEC 60794-1-215:2020 © IEC 2020
4.4 Procedure
1) Place the cable gauge length in the water tank, either as a coil or by coiling it into the tank.
Cover the cable with water.
2) Perform initial attenuation measurements as indicated by the detail specification.
3) If the optional temperature monitoring device is used, the chamber temperature may be
lowered so far as to −40 °C until the ice is completely frozen and the ice temperature is
−10 °C or lower.
4) Raise the chamber temperature to −2 °C and hold this temperature for 1 h.
NOTE This is the temperature at which pure water experiences its greatest volume expansion as ice.
5) Measure the attenuation as indicated by the detail specification.
6) Elevate the chamber temperature to melt the ice. If the optional temperature monitoring
device is used, the chamber temperature may be raised so high as to +65 °C, in order to
accelerate the ice melting. Maintain the high temperature until the water reaches +15 °C.
Then, return the chamber temperature to +23 °C and hold this temperature until the water
reaches +23 °C ± 5 °C.
7) Measure the attenuation as indicated by the detail specification.
8) Remove the cable from the water tank and examine the exterior of the gauge length for any
physical damage.
4.5 Requirements
After exposure, there shall be no visible cracks or other openings in the cable sheath. The
maximum increase in attenuation during and after the test shall be as shown in the relevant
detail specification, when frozen and no change after thawing.
4.6 Details to be specified
The detail specification shall include the following:
a) change of attenuation during and after the test;
b) any deviations from the criteria specified herein;
c) minimum bend diameter.
5 Method F15B – Cable external freezing test in a rigid conduit (duct)
5.1 Object
This test determines the ability of a cable to withstand the effects of freezing water in a rigid
conduit (duct) that can immediately surround the optical fibre cable sheath by observing any
changes in the physical appearance of the sheath, or in the measured cable optical attenuation.
NOTE This external freezing test of F15B simulates freezing of the medium surrounding an outside cable in a rigid
conduit (duct). The similar test of F15A addresses the freezing of a medium surrounding a buried cable, as wet earth
or water, thus not constrained by a rigid duct.
5.2 Sample
The sample length shall be of a length sufficient to carry out the specified test. Additional length
sufficient to make the required optical measurements and to connect the cable from the
apparatus to the measuring equipment shall be provided. The sample length shall be as
specified by the detail specification. The sample shall be loosely installed in the conduit (duct).
NOTE The typical sample length is longer than L when the sample gauge length of L is 5 m.
1 1
5.3 Apparatus
The apparatus (see Figure 1) shall be the conduit (duct) suitable to contain the sample gauge
length (L , per the detail specification, typically 5 m) covered with water. To keep the water in
the conduit (duct) without water blocking or sealing, the entrances of the conduit (duct) are
gradually curved with a sufficient large bending radius with no change of the physical and optical
property of the sample. The water shall be common tap water.

Figure 1 – Example of F15B apparatus of cable external freezing test in a rigid conduit
This procedure is written in view of the use of tap water. Other types of water, such as sea
water or the like, shall be as specified by the detail specification. In these cases, the detail
specification may need to prescribe temperatures other than those specified herein.
The conduit (duct) shall be positioned in a climatic chamber suitable for freezing the water.
The climatic chamber of a suitable size to accommodate the sample and whose temperature
shall be controllable to remain within ±3 °C of the specified testing temperature shall be used.
Optionally, a temperature monitoring device may be used to monitor the cable temperature or
nearby position temperature of the cable. In this case, the device shall be in close proximity to
the sample under test.
NOTE 1 For example, thermocouple can be used as the device to monitor the temperature near the sample.
Conventionally, the thermocouples are attached on the outer surface of the conduit (duct).
A heat insulating material is arranged at the central section (L , per the detail specification,
typically 1 m to 2 m) of the conduit to delay freezing the water in this section.
NOTE 2 In the field, the temperature of the conduit depends on the buried depth. The freezing delay between the
central section and the others can well simulate freezing the water in the conduit in the underground.
An attenuation measuring apparatus for the determination of attenuation changes shall comply
with IEC 60793-1-46.
5.4 Procedure
1) Place the cable gauge length in the conduit (duct). Fill the conduit (duct) and cover the
cable with water.
As required by the detail specification, freezing pressure absorber elements, such as a cable
outer element, shall be placed in the conduit (duct) with the cable sample.
NOTE 1 For example, a cable outer element is a specially designed PE pipe (see [3] and Annex A). The
preponderance of experience with freezing of cables in ducts indicates that some sort of pressure absorber
element is important for acceptable performance of installed duct cable subject to freezing.
2) The sample at ambient temperature shall be introduced into the climatic chamber which is
also at that temperature.
– 10 – IEC 60794-1-215:2020 © IEC 2020
3) Perform initial attenuation measurements as indicated by the detail specification.
4) If specified, after that, measure the attenuation with a period of specified time of t (typically
s
1 h) during the test.
NOTE 2 The optional measurement of the attenuation during the test can terminate the test as soon as the
attenuation change exceeds the specified criteria.
5) The temperature in the chamber shall then be lowered to the specified low temperature T
A
(typically −20°C).
6) After temperature stability in the chamber has been reached, the sample shall be exposed
(typically 40 h). At the end of
to the low temperature conditions for the appropriate period t
the exposure to low temperature conditions, the attenuation shall be measured.
7) The temperature in the chamber shall then be raised to the specified high temperature T
B
(typically 60°C), in order to accelerate the ice melting. Maintain the high temperature for the
appropriate period t (typically 3 h). Then, return the chamber temperature to the ambient
temperature.
8) The steps 3) through 7) constitute one cycle.
9) The sample shall be subjected to 3 cycles unless otherwise required in the relevant detail
specification.
10) At the end of the last cycle, the sample shall be held at ambient temperature for the
appropriate period t (typically 6 h).
11) The sample under test and the chamber shall have reached temperature stability at ambient
temperature.
12) Remove the cable from the conduit (duct) and examine the exterior of the gauge length (L )
for any physical damage.
5.5 Requirements
After exposure, there shall be no visible cracks or other openings in the cable sheath. The
maximum increase in attenuation during and after the test shall be as shown in the relevant
detail specification, when frozen and no change after thawing.
5.6 Details to be specified
The detail specification shall include the following:
a) change of attenuation during and after the test;
b) any deviations from the criteria specified herein;
c) length and outer diameter of cable sample;
d) conduit (duct) length;
e) inner and outer diameters, thickness and material of conduit (duct);
f) length, material and thickness of thermal insulating material;
g) number of fibres to be tested;
h) number of cycles, if other than three;
i) change of attenuation at a specified wavelength as a function of temperature cycling; that
is, at the required values of T and ambient after;
A
j) number of cables in the conduit (duct);
k) as required, number of freezing pressure absorber elements, such as outer cable elements;
l) if required, specification of the freezing pressure absorber elements such as typical outer
diameter and detailed configuration of outer cable element.

Annex A
(informative)
Example of freezing pressure absorber elements
Annex A shows a typical measure to protect the cable in the rigid conduit from freezing water.
In general, the volume of the water expands by about 10 % after the water freezing. This causes
to increase the inner pressure in the rigid conduit. The outer pressure of the cable in the rigid
conduit simultaneously increases and then the optical loss of the cable will be degraded.
Figure A.1 shows an example of freezing pressure absorber elements which are made of the
special designed polyethylene (PE) pipe including the air tubes (pipe part) separated in the
period of 2 m by the sealing part of 50 mm.
Figure A.2 shows the cross section of the rigid conduit with an optical cable and three special
designed PE pipe shown in Figure A.1. The PE pipes are collapsed by the freezing water
pressure in the rigid conduit. The inner air is still kept in the collapsed air tube section of the
PE pipe. So, the PE pipes act as freezing pressure absorber. After melting ice, gradually the
collapsed air sections of the PE pipes are restored to initial status. Repeatedly, the PE pipe
acts as the absorber to protect the cable in the rigid conduit from freezing water.
Therefore,
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