IEC TR 62470:2011

IEC/TR 62470 ®
Edition 1.0 2011-10
TECHNICAL
REPORT
colour
inside
Guidance on techniques for the measurement of the coefficient of friction (COF)
between cables and ducts
IEC/TR 62470:2011(E)
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IEC/TR 62470 ®
Edition 1.0 2011-10
TECHNICAL
REPORT
colour
inside
Guidance on techniques for the measurement of the coefficient of friction (COF)
between cables and ducts
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
N
ICS 33.180.10 ISBN 978-2-88912-744-3

– 2 – TR 62470 © IEC:2011(E)
CONTENTS
FOREWORD . 3
1 Scope and object . 5
2 Reference documents . 5
3 Test procedures . 6
3.1 Method A: wheel test . 6
3.1.1 General . 6
3.1.2 Sample . 6
3.1.3 Apparatus . 6
3.1.4 Procedure . 7
3.1.5 Calculations. 7
3.1.6 Results . 8
3.2 Method B: sloped duct test . 8
3.2.1 General . 8
3.2.2 Sample . 9
3.2.3 Apparatus . 9
3.2.4 Procedure . 10
3.2.5 Calculations. 10
3.2.6 Results . 10
3.3 Method C: sloped cable test . 11
3.3.1 General . 11
3.3.2 Sample . 11
3.3.3 Apparatus . 11
3.3.4 Procedure . 12
3.3.5 Calculations. 12
3.3.6 Results . 12
Bibliography . 14

Figure 1 – Sketch of a wheel test . 7
Figure 2 – Sketch of the sloped duct test . 9
Figure 3 – Sketch of the sloped cable test. . 12

TR 62470 © IEC:2011(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
GUIDANCE ON TECHNIQUES FOR THE MEASUREMENT OF
THE COEFFICIENT OF FRICTION (COF) BETWEEN CABLES AND DUCTS

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
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The main task of IEC technical committees is to prepare International Standards. However, a
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data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC TR 62470, which is a technical report, has been prepared by subcommittee 86A: Fibres
and cables, of IEC technical committee 86: Fibre optics.
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
86A/1407/DTR 86A/1417/RVC
Full information on the voting for the approval of this technical report can be found in the
report on voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 4 – TR 62470 © IEC:2011(E)
The committee has decided that the contents of this publication will remain unchanged until
the stability 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.
A bilingual version of this publication may be issued at a later date.

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.
TR 62470 © IEC:2011(E) – 5 –
GUIDANCE ON TECHNIQUES FOR THE MEASUREMENT OF
THE COEFFICIENT OF FRICTION (COF) BETWEEN CABLES AND DUCTS

1 Scope and object
This technical report describes three techniques to measure the coefficient of friction (COF)
between cables and ducts. For a given technique, cable construction, installation method
(pulling, pushing, or blowing), and duct size, the relative values of the COF can give some
indication as to the relative ease of installation. The techniques can be used for traditional
cables and ducts (see IEC 60794-3-10) as well as for microduct cables and microducts (see
IEC 60794-5). A fibre or fibre unit may be evaluated in place of a cable in all techniques.
Methods A, B, and C are distinguished by the equipment used for measurements:
• method A – using a wheel around which the duct is wound, a cable with attached weight
being pulled through the latter, while measuring the force needed for this;
• method B – using a device to clamp a duct specimen, a cable specimen placed inside,
tilting both while measuring the angle at which the cable specimen starts to slide, or the
angle which sustains sliding; and
• method C – using a device to clamp and straighten a cable specimen, a duct specimen
placed around it, tilting both while measuring the angle at which the duct specimen starts
to slide, or the angle which sustains sliding.
The COF when the cable is not moving with respect to the duct is the static COF, and will
increase until sliding suddenly starts. The COF while the cable is sliding within the duct is the
kinetic or dynamic COF. It should be noted that the static COF will generally be a higher value
than the kinetic COF.
The results from the three methods can be compared qualitatively, but are not represented as
being equivalent. None of the methods are represented as being the Reference Test Method.
Method A will yield the kinetic COF; methods B and C will yield both static and kinetic COF.
Both the static and kinetic COF may be dramatically affected by lubrication of the cable and/or
duct. While not specifically addressed herein, the intent of these methods may be used with
lubricated cable/duct samples.
These methods do not constitute a routine test used in the general evaluation of the
installation performance of cables in ducts. This parameter is not generally specified within a
detail specification.
2 Reference documents
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 documents (including any amendments) applies.
IEC 60794-1-1:2001, Optical fibre cables – Part 1-1: Generic specification – General
IEC 60794-3-10: Optical fibre cables – Part 3-10: Outdoor cables – Family specification for
duct, directly buried and lashed aerial optical telecommunication cables
IEC 60794-5: Optical fibre cables – Part 5: Sectional specification – Microduct cabling for
installation by blowing
– 6 – TR 62470 © IEC:2011(E)
3 Test procedures
3.1 Method A: wheel test
3.1.1 General
This subclause describes a technique for the measurement of the COF between a cable
specimen and a duct specimen, an important parameter for the installation performance
(pushing, pulling, blowing, etc.) of the cable in the duct; see IEC 60794-1-1:2001, Annex C (to
be IEC/TR 62691). This method particularly evaluates the friction seen when a cable travels
around a curve in a duct.
In this method, a cable specimen with attached weight is pulled through a duct specimen
wound around the wheel and the pulling force is measured.
Several variants of wheel tests are used with different weights, diameters, and angles over
which the duct is pulled over the wheel. Sometimes a pulley is also used to direct the cable in
line with the pulling/force-measuring device. One variant is given here as an example.
3.1.2 Sample
The test sample comprises a duct specimen and a cable specimen of the type under
consideration. A new, cle
...