IEC 60794-1-201:2024

Optical fibre cables - Part 1-201: Generic specification - Basic optical cable test procedures - Environmental test methods - Temperature cycling, method F1

IEC 60794-1-201: 2024 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 temperature cycling by observing changes in attenuation. See IEC 60794-1-2 for a reference guide to test methods of all types and for general requirements and definitions.
This document partially replaces IEC 60794-1-22:2017. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to IEC 60794-1-22:2017:
a) all references to the temperature sensing device have been removed and replaced with a note "for further study";
b) the conditioning procedure has been separated into Procedure 1 and Procedure 2 to avoid confusion;
c) the ambient temperature test condition has been defined as per IEC 60794-1-2;
d) the minimum soak time has been decreased for sample mass >16 kg in Table 1.

Câbles à fibres optiques - Partie 1-201: Spécification générique - Procédures fondamentales d’essai des câbles optiques - Méthodes d’essai d’environnement - Cycles de température, méthode F1

L’IEC 60794-1-201:2024 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 l’aptitude d’un câble à résister aux effets de cycles de température, en observant les variations de l’affaiblissement.
Se reporter à l’IEC 60794-1-2 comme guide de référence des méthodes d’essai de tous types, et pour consulter les exigences générales et les définitions.

General Information

• Status: Published
• Publication Date: 29-May-2024
• ICS: 33.180.10 - Fibres and cables
• Technical Committee: SC 86A - Fibres and cables
• Current Stage: PPUB - Publication issued
• Start Date: 30-May-2024
• Completion Date: 07-Jun-2024

Relations

• Replaces: IEC 60794-1-22:2017 - Optical fibre cables - Part 1-22: Generic specification - Basic optical cable test procedures - Environmental test methods
• Effective Date: 05-Sep-2023

IEC 60794-1-201:2024 – Optical Fibre Cable Temperature Cycling Test Standard

Overview

IEC 60794-1-201:2024 establishes uniform environmental test procedures focused on the temperature cycling method F1 for assessing the durability and reliability of optical fibre cables. This international standard is critical for manufacturers, testers, and users of optical fibre cables and cables combining optical fibres with electrical conductors. It defines how to simulate temperature fluctuations in real-world conditions to evaluate changes in optical attenuation-key for ensuring cable performance and longevity across diverse operating environments.

This updated edition partially replaces IEC 60794-1-22:2017 with technical revisions that refine conditioning procedures, ambient temperature definitions, and soak times for larger cable samples. The goal is to provide a consistent, precise method to verify cable robustness against temperature-induced mechanical stresses.

Key Topics

• Scope and Applicability

  • Applicable to optical fibre cables used in telecommunications and related devices
  • Also covers hybrid cables containing both optical fibres and electrical conductors
  • Includes optical fibre units and microduct fibre units as part of the "optical cable" definition

• Objective of Method F1

  • Test cable sample stability by subjecting it to cycles of temperature changes
  • Observe attenuation variation caused by fibre buckling or tension due to thermal expansion differences
  • Evaluate cable performance under storage, transport, and service conditions

• Test Procedure Highlights

  • Samples typically ≥500 meters to ensure attenuation measurement accuracy
  • Conditioning divided into two procedures to enhance clarity and reproducibility
  • Temperature cycling simulates worst-case environmental conditions
  • Measurement stages include preconditioning, initial measurements, conditioning cycles, and recovery assessment

• Changes in the 2024 Edition

  • Removal of temperature sensing device references, replaced with notes for future study
  • Ambient temperature test conditions aligned with IEC 60794-1-2
  • Reduced minimum soak times for samples over 16 kg implemented
  • Enhanced clarity to avoid confusion during conditioning phases

Applications

The IEC 60794-1-201:2024 standard is essential for:

• Telecommunication Cable Manufacturers – to validate and certify that optical fibre cables meet international environmental durability requirements before market release
• Network Infrastructure Providers – to ensure cables maintain transmission quality despite environmental stresses such as temperature fluctuations during installation or operation
• Test Laboratories – providing standardized methods to evaluate cable attenuation stability, enabling consistent, comparable results across different facilities and regions
• Research & Development Teams – to develop new fibre optic cables or components resistant to temperature-induced mechanical stress and signal attenuation
• Hybrid Cable Systems – verifying the combined mechanical and optical performance of cables that integrate electrical and optical elements

Related Standards

• IEC 60794-1-2: Generic Specification – Basic optical cable test procedures – General guidance and definitions supporting method F1
• IEC 60794-1-22:2017: Previous edition partially replaced by this standard, contains related environmental test methods
• IEC 60794-1-212 (Method F12): Temperature cycling with fixed cable ends to measure attenuation stability for terminated cables
• IEC 60794-1-209 (Method F9): Ageing test which incorporates temperature cycling as part of the overall evaluation
• IEC 60794-1-217 (Method F17): Cable shrinkage and fibre protrusion testing due to thermal exposure

Practical Value

By adhering to IEC 60794-1-201:2024, stakeholders can ensure:

• Optical fibre cables exhibit predictable, stable attenuation behavior under environmental temperature cycling
• Compliance with internationally recognized test methods enhances product credibility and acceptance
• Improved understanding and mitigation of temperature-related mechanical effects on optical fibres, reducing network failures and maintenance costs
• Harmonized test results that support global supply chains and facilitate regulatory approvals

This standard represents a fundamental tool for ensuring optical fibre cable performance and supporting the expanding demands of telecommunication infrastructure worldwide. Utilizing IEC 60794-1-201 enhances quality, reliability, and customer confidence in fibre optic network components.

Standards Content (Sample)

IEC 60794-1-201 ®
Edition 1.0 2024-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Optical fibre cables –
Part 1-201: Generic specification – Basic optical cable test procedures –
Environmental test methods – Temperature cycling, method F1
Câbles à fibres optiques –
Partie 1-201: Spécification générique – Procédures fondamentales d’essai des
câbles optiques – Méthodes d’essai d’environnement – Cycles de température,
méthode F1
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IEC 60794-1-201 ®
Edition 1.0 2024-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Optical fibre cables –
Part 1-201: Generic specification – Basic optical cable test procedures –
Environmental test methods – Temperature cycling, method F1
Câbles à fibres optiques –
Partie 1-201: Spécification générique – Procédures fondamentales d’essai des
câbles optiques – Méthodes d’essai d’environnement – Cycles de température,
méthode F1
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.180.10 ISBN 978-2-8322-8934-1
– 2 – IEC 60794-1-201:2024 © IEC 2024
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Method F1 – Temperature cycling . 7
4.1 Object . 7
4.2 Sample . 7
4.3 Apparatus . 8
4.4 Procedure . 8
4.4.1 Preconditioning . 8
4.4.2 Initial measurement . 8
4.4.3 Conditioning . 8
4.4.4 Recovery . 11
4.5 Requirements . 11
4.6 Details to be specified . 11
4.7 Details to be reported . 12
Bibliography . 13

Figure 1 – Initial cycle(s) procedure . 10
Figure 2 – Final cycle procedure . 11

Table 1 – Minimum soak time t . 10
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
OPTICAL FIBRE CABLES –
Part 1-201: Generic specification –
Basic optical cable test procedures –
Environmental test methods –
Temperature cycling, method F1

FOREWORD
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shall not be held responsible for identifying any or all such patent rights.
IEC 60794-1-201 has been prepared by subcommittee 86A: Fibres and cables, of IEC technical
committee 86: Fibre optics. It is an International Standard.
This document partially replaces IEC 60794-1-22:2017. This edition constitutes a technical
revision.
This edition includes the following significant technical changes with respect to
IEC 60794-1-22:2017:
a) all references to the temperature sensing device have been removed and replaced with a
note "for further study";
– 4 – IEC 60794-1-201:2024 © IEC 2024
b) the conditioning procedure has been separated into Procedure 1 and Procedure 2 to avoid
confusion;
c) the ambient temperature test condition has been defined as per IEC 60794-1-2;
d) the minimum soak time has been decreased for sample mass >16 kg in Table 1.
The text of this International Standard is based on the following documents:
Draft Report on voting
86A/2438/FDIS 86A/2463/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
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 webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
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that it contains colours which are considered to be useful for the correct understanding
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INTRODUCTION
This document cancels and replaces method F1 of IEC 60794-1-22:2017, which will be
withdrawn. It includes an editorial revision, based on the new structure and numbering system
for optical fibre cable test methods. Additionally, technical changes were implemented. The
environmental tests contained in IEC 60794-1-22:2017 will be individually numbered in the
IEC 60794-1-2xx series. Each test method is now considered to be an individual document
rather than part of a multi-test method compendium. Full cross-reference details are given in
IEC 60794-1-2.
The numbering of this test method continues the F-series numbering sequence of
IEC 60794-1-22:2017.
– 6 – IEC 60794-1-201:2024 © IEC 2024
OPTICAL FIBRE CABLES –
Part 1-201: Generic specification –
Basic optical cable test procedures –
Environmental test methods –
Temperature cycling, method F1

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 temperature cycling by observing changes in attenuation.
See IEC 60794-1-2 for a reference guide to test methods of all types and for general
requirements and definitions.
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 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
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp

4 Method F1 – Temperature cycling
4.1 Object
This measuring method applies to optical fibre cables, which are tested by temperature cycling
in order to determine the stability behaviour of the attenuation of cables submitted to
temperature changes. This method can also be used for evaluation of buffer tubes or other
elements independent of a cable construction, as defined by a detail specification.
Changes in the attenuation of optical fibre cables, which can occur with changing temperature,
are generally the result of buckling or tensioning of the fibres resulting from differences between
their thermal expansion coefficient and the coefficients of the cable strength and sheath
members. Test conditions for temperature-dependent measurements shall simulate the worst
conditions.
This test can be used either for monitoring cable behaviour in the temperature range, which can
occur during storage, transportation and usage, or to check, in a selected temperature range
(usually wider than that required for the above-mentioned cases), the stability behaviour of the
attenuation connected to a substantially microbend-free situation of the fibre within the cable
structure.
NOTE 1 Method F12 in IEC 60794-1-212 is similar to this method, but with cable elements fixed at both sample
ends. Method F12 assesses the attenuation behaviour of a cable without end movement intended for termination
with, for example, interconnecting devices or passive components.
NOTE 2 The ageing test, method F9 in IEC 60794-1-209, uses method F1 as its pre- and post-test temperature
cycle. Often these tests are performed together.
NOTE 3 The cable shrinkage (fibre protrusion) test, method F17, is similar to this method, but it determines the
permanent fibre protrusion compared to the cable elements and the cable sheath due to thermal exposure of a cable.
4.2 Sample
The sample shall be of length appropriate to achieve the desired accuracy of attenuation
measurements (generally ≥500 m). This may be a factory length, or a sample of sufficient length
as indicated in the detail specification. The sample is additionally defined as the cable sample
as deployed for testing.
In order to gain reproducible values, the cable sample shall be brought into the climatic chamber
in a manner such that the deployment does not affect the measurement. Such methods could
be a loose coil or on a reel with large diameter coils, cushioned reels with a soft layer or a zero-
tension facility device.
The ability of the fibre(s) to accommodate differential expansion and contraction (e.g. by
slipping within the cable) could be influenced by the bending radius of the cable. Sample
conditioning should, therefore, be realized as close as possible to normal usage conditions.
The bend diameter of the cable sample shall not violate the minimum bend diameter of the
cable, tube or other unit as specified by the detail specification (generally around 20X cable
OD).
Potential problems are due to an actual difference between the expansion coefficients of the
test sample and of the holder (e.g. reel, basket, plate) which can induce, during thermal cycles,
a significant effect on the test result if "no effect" conditions are not completely fulfilled. The
intent is to simulate the installed condition, in which the cable is generally straight for the
majority of its length.
Parameters of influence are mainly the details of conditioning, the type and materials of the
holder, and the diameter of the sample coil or reel.

– 8 – IEC 60794-1-201:2024 © IEC 2024
General recommendations include the following:
a) The winding diameter shall be large enough to keep the ability of the fibre to accommodate
differential expansion and contraction. A winding diameter substantially greater than the
value selected for cable delivery can be necessary.
b) Any risk of cable expansion (or contraction) limitation created by conditioning shall be
suppressed. In particular, special care should be taken to avoid residual tension on the
cable during the test. For example, a tight winding on a drum is not recommended as it can
limit cable contraction at low temperature. On the other hand, a tight multilayer winding can
limit expansion at high temperature.
c) The use of loose winding is recommended with large diameter coils and cushioned reels
with a soft layer or zero tension facility device.
d) The number of fibres tested shall conform to IEC 60794-1-1.
e) The fixed cable ends as well as connection to the equipment shall be outside of the
temperature chamber to avoid negative influences.
In order to limit the length of the cable under test, it is permissible to concatenate several fibres
of the cable and to measure the concatenated fibres. The number of connections shall be limited,
and they should be located outside the climatic chamber.
4.3 Apparatus
The apparatus shall consist of the following.
a) An appropriate attenuation measuring apparatus for the determination of attenuation change
(see the test methods of IEC 60793-1-46).
b) a climatic chamber of a suitable size to accommodate the sample whose temperature shall
be controllable to remain within ±3 °C of the specified testing temperature. One example of
a suitable chamber is given in Clause 8 of IEC 60068-2-14:2023.
4.4 Procedure
4.4.1 Preconditioning
The sample shall be preconditioned at standard ambient temperature conditions as defined in
IEC 60794-1-2.
4.4.2 Initial measurement
The sample shall be visually inspected and a basic value for attenuation at the initial
temperature shall be determined.
4.4.3 Conditioning
Procedure 1
If only one high and low temperature is specified in the detail specification, then Procedure 1 is
applicable. Figure 1 shall be used for the initial cycle(s) and the final cycle during the test.
Throughout this procedure, the ambient temperature condition is the standard test condition as
defined in IEC 60794-1-2.
1) The sample at ambient temperature shall be introduced into the climatic chamber which is
also at that temperature.
2) The temperature in the chamber shall then be lowered to the appropriate low temperature
T at a rate of cooling not to exceed 60 °C per hour, unless otherwise specified.
A2
3) After the temperature within the chamber has stabilized, the sample shall soak at
temperature T for the appropriate period t (see step 4)).
A2 1
4) A minimum soak time is given in Table 1; however, the soak time, t , shall be sufficient to
bring the complete cable to equilibrium with the specified temperature.
NOTE 1 Cable temperature sensing device to measure the temperature of the cable sample is for further study.
5) The temperature in the chamber shall then be raised to the appropriate high temperature
T at a rate of heating not to exceed 60 °C per hour, unless otherwise specified.
B2
6) After the temperature within the chamber has stabilized, the sample shall soak at
temperature T for the appropriate period t .
B2 1
7) The temperature in the chamber shall then be lowered to the value of the ambient
temperature at the appropriate rate of cooling. This procedure constitutes one cycle. If this
is the intermediate step in a series of cycles, no soak is required, and no measurements
shall be taken.
8) Continue to the next cycles, using steps 2) through 7). The sample shall be subjected to at
least two cycles unless otherwise required by the relevant detail specification. At the end of
the cycling sequence, hold the sample at ambient temperature for the appropriate period t .
9) The change in attenuation shall be measured at ambient temperature at the start of the first
cycle, at the end of the soak time t at each of the specified temperature steps (T , T ) in
1 A2 B2
the final cycle, and at ambient temperature at the end of the final cycle. If measurement at
intermediate cycles is required by the detail specification, the measurements shall be
performed in the same manner.
10) Before removal from the chamber, the sample under test shall have reached temperature
stability at ambient temperature.
Procedure 2
If multiple (two or more) low or high temperatures are specified in the detail specification, then
Procedure 2 is applicable. Figure 1 shall be used for the initial cycle(s) except for the final cycle
and Figure 2 shall be used for the final cycle during the test. Throughout this procedure, the
ambient temperature condition is the standard test condition as defined in IEC 60794-1-2.
1) The sample at ambient temperature shall be introduced into the climatic chamber which is
also at that temperature.
2) Using steps 2) through 7) of Procedure 1 for the initial cycle(s) (except for the final cycle).
NOTE 2 T here is the extreme low temperature among multiple low temperatures and T here is the extreme
A2 B2
high temperature among multiple high temperatures.
3) During the last cycle, the sample shall be held at each intermediate temperature (T or
A1
T ) and each extreme temperature (T or T ) for the appropriate time t , as per Figure 2.
B1 A2 B2 1
At the end of the cycling sequence, hold the sample at ambient temperature for the
appropriate period t .
4) The sample shall be subjected to at least totally two cycles (one initial cycle and one final
cycle) unless otherwise required by the relevant detail specification. The change in
attenuation shall be measured at ambient temperature at the start of the first cycle, at the
end of the soak time t at each of the specified temperature steps (T , T , T , T ) in the
1 A1 A2 B1 B2
final cycle, and at ambient temperature at the end of the final cycle. If measurement at
intermediate cycles is required by the detail specification, the measurements shall be
performed in the same manner.
5) Before removal from the chamber, the sample under test shall have reached temperature
stability at ambient temperature.

– 10 – IEC 60794-1-201:2024 © IEC 2024
Table 1 – Minimum soak time t
Minimum soak times for a given sample mass (weight of cable under test)
Sample mass Minimum soak time, t
kg h
Under 0,35 0,5
0,36 to 0,7 1
0,8 to 1,5 2
1,6 to 100 4
101 to 250 6
251 to 500 8
Over 501 12
NOTE 1 It is the responsibility of the tester to assure that the soak time is long enough to bring the cable to
equilibrium with the specified temperature.
NOTE 2 If more than one sample is put into the chamber, compare the largest sample mass of all single samples
with the values in the table for the determination of the minimum soak time.

Figure 1 – Initial cycle(s) procedure

Figure 2 – Final cycle procedure
4.4.4 Recovery
The sample shall be allowed to attain temperature stability at the standard ambient temperature
condition.
The relevant detail specification can call for a specific recovery period for a given type of sample.
4.5 Requirements
The acceptance criteria for the test shall be as stated in the detail specification. Typical failure
modes include loss of optical continuity, degradation of optical transmittance, or physical
damage to the cable. Unless otherwise specified, the change in attenuation shall be calculated
with respect to the attenuation value attained at ambient conditions prior to the start of the
temperature cycling test (4.4.2).
4.6 Details to be specified
The detail specification shall include the following:
a) cable sample length;
b) number of fibres tested if different from 4.2;
c) length of the fibre under test (if concatenated);
d) type of connection between concatenated fibres (optional);
e) temperature limits:
i) T and T (Figure 1), or
A2 B2
ii) T , T , T and T (Figure 2);
A1 A2 B1 B2
f) number of cycles;
g) humidity levels at each temperature extreme (if specified);
h) maximum change in attenuation (see 4.5) at the specified wavelength(s) during and after
test.
– 12 – IEC 60794-1-201:2024 © IEC 2024
4.7 Details to be reported
The test report shall include the following information:
a) type of winding: coil, reel, other (to be stated, in case of a cushioned reel, the type of
cushioning and material used); winding diameter; single or multilayer; winding tension and
zero tension facility device (if any);
b) soak time, t ;
c) description of the sample type;
d) description of used test and measurement equipment;
e) change in attenuation at the specified wavelength(s) during and after test;
f) any deviations from these test procedures.
...