IEC 60851-3:2023

IEC 60851-3 ®
Edition 4.0 2023-08
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Winding wires – Test methods –
Part 3: Mechanical properties
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IEC 60851-3 ®
Edition 4.0 2023-08
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Winding wires – Test methods –
Part 3: Mechanical properties
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.060.10 ISBN 978-2-8322-7448-4

– 2 – IEC 60851-3:2023 RLV © IEC 2023
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 8
4 Test 6: Elongation . 8
4.1 Elongation at fracture . 8
4.2 Tensile strength . 9
5 Test 7: Springiness . 9
5.1 General . 9
5.2 Round wire with a nominal conductor diameter from 0,080 mm up to and
including 1,600 mm . 9
5.2.1 Principle . 9
5.2.2 Equipment . 9
5.2.3 Procedure . 11
5.3 Round wire with a nominal conductor diameter over 1,600 mm and
rectangular wire . 12
5.3.1 Principle . 12
5.3.2 Equipment . 12
5.3.3 Specimen . 13
5.3.4 Procedure . 13
6 Test 8: Flexibility and adherence . 14
6.1 General . 14
6.2 Mandrel winding test . 14
6.2.1 Round wire . 14
6.2.2 Rectangular wire. 15
6.2.3 Covered bunched wire . 16
6.3 Stretching test (applicable to enamelled round wire with a nominal conductor
diameter over 1,600 mm) . 16
6.4 Jerk test (applicable to enamelled round wire with a nominal conductor
diameter up to and including 1,000 mm) . 17
6.5 Peel test (applicable to enamelled round wire with a nominal conductor
diameter over 1,000 mm) . 17
6.6 Adherence test . 19
6.6.1 General . 19
6.6.2 Enamelled rectangular wire . 19
6.6.3 Impregnated fibre covered round and rectangular wire . 19
6.6.4 Fibre covered enamelled round and rectangular wire . 19
6.6.5 Tape-wrapped round and rectangular wire (for adhesive tape only) . 20
7 Test 11: Resistance to abrasion (applicable to enamelled round wire) . 20
7.1 General . 20
7.2 Principle . 20
7.3 Equipment . 20
7.4 Procedure . 21
8 Test 18: Heat bonding (applicable to enamelled round wire with a nominal
conductor diameter over 0,050 mm up to and including 2,000 mm and to
enamelled rectangular wire) . 22

8.1 General . 22
8.2 Vertical bond retention of a helical coil . 22
8.2.1 General . 22
8.2.2 Nominal conductor diameter up to and including 0,050 mm . 22
8.2.3 Nominal conductor diameter over 0,050 mm up to and including

2,000 mm . 22
8.3 Bond strength of a twisted coil . 25
8.3.1 General . 25
8.3.2 Principle . 25
8.3.3 Equipment . 25
8.3.4 Specimen . 25
8.3.5 Procedure . 27
8.3.6 Result . 27
8.4 Enamelled rectangular wire heat bonding . 28
Annex A (informative) Bond strength of heat bonding wires . 30
A.1 Calculation of the temperature of the twisted coil specimen . 30
A.1.1 Method . 30
A.1.2 Temperature coefficient . 30
A.1.3 Calculation . 30
A.2 Determination of the heating period . 31
A.2.1 Voltage-time graphs. 31
A.2.2 Voltage at maximum temperature . 31
Annex B (informative) Friction test methods . 36
B.1 General . 36
B.2 Test A: Static coefficient of friction test method . 36
B.2.1 Test method (applicable to enamelled round wires with a nominal
conductor diameter from 0,050 mm up to and including 1,600 mm) . 36
B.2.2 Test apparatus . 36
B.3 Test B: First dynamic coefficient of friction test method . 37
B.3.1 Principle . 37
B.3.2 Method of test. 37
B.4 Test C: Second dynamic coefficient of friction test method (applicable to
enamelled round wires with a nominal conductor diameter from 0,050 mm up
to and including 1,600 mm) . 37
B.4.1 Test equipment . 37
B.4.2 Test specimen . 38
B.4.3 Specimen preparation . 38
B.4.4 Procedure . 39
B.5 Test D: Force of friction by the twisted pair method . 40
B.5.1 Enamelled round wires with a nominal conductor diameter from 0,1 mm
up to and including 1,500 mm . 40
B.5.2 Test method . 40
Bibliography . 46

Figure 1 – Test equipment to determine springiness . 10
Figure 2 – Construction and details of the mandrel (see Table 1) . 10
Figure 3 – Test equipment to determine springiness . 13
Figure 4 – Test equipment for mandrel winding test . 16
Figure 5 – Test equipment for jerk test . 17

– 4 – IEC 60851-3:2023 RLV © IEC 2023
Figure 6 – Test equipment for peel test . 18
Figure 7 – Scraper . 19
Figure 8 – Cross-section of the wire after removal of the coating . 19
Figure 9 – Test equipment for unidirectional scrape test . 21
Figure 10 – Test equipment for bond retention of a helical coil . 24
Figure 11 – Coil winder . 26
Figure 12 – Oval shape coil . 27
Figure 13 – Twisting device with a load applied to the twisted coil specimen. 27
Figure 14 – Arrangement of supports . 28
Figure 15 – Samples for heat bonding . 29
Figure A.1 – Example of voltage-time graphs of twisted coil specimens with a nominal
conductor diameter of 0,300 mm with isothermic graphs . 32
Figure A.2 – Example of voltage-time graphs of twisted coil specimens with a nominal

conductor diameter of 0,315 mm with isothermic graphs . 33
Figure A.3 – Example of voltage-time graphs of twisted coil specimens with a nominal
conductor diameter of 0,355 mm with isothermic graphs . 34
Figure A.4 – Example of voltage-time graphs of twisted coil specimens with a nominal
conductor diameter of 0,500 mm with isothermic graphs . 35
Figure B.1 – Static coefficient of friction test apparatus . 41
Figure B.2 – Dynamic coefficient of friction test apparatus . 42
Figure B.3 – Diagram of a typical dynamic coefficient of friction tester . 43
Figure B.4 – Material – sapphire (synthetic) . 44
Figure B.5 – Synthetic sapphires mounted on load block . 44
Figure B.6 – Load applied perpendicular to wire path . 45
Figure B.7 – Twisted specimen . 45

Table 1 – Mandrels for springiness . 11
Table 2 – Magnification to detect cracks . 14
Table 3 – Load for peel test . 18
Table 4 – Preparation of helical coils . 23
Table 5 – Bond retention at elevated temperature . 24
Table B.1 – Load block weights for dynamic coefficient of friction testing . 39
Table B.2 – Twisted pair method . 40

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
WINDING WIRES – TEST METHODS –

Part 3: Mechanical properties
FOREWORD
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
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shall not be held responsible for identifying any or all such patent rights.
This redline version of the official IEC Standard allows the user to identify the changes
made to the previous edition IEC 60851-3:2009+AMD1:2013+AMD2:2019 CSV. A vertical
bar appears in the margin wherever a change has been made. Additions are in green text,
deletions are in strikethrough red text.

– 6 – IEC 60851-3:2023 RLV © IEC 2023
IEC 60851-3 has been prepared by IEC technical committee 55: Winding wires. It is an
International Standard.
This fourth edition cancels and replaces the third edition published in 2009, Amendment 1:2013
and Amendment 2:2019. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) Clarification of the distance measurement for determining loss of adhesion in 6.6.3, 6.6.4
for fibre-covered wires and 6.6.5 for tape-wrapped wires.
The text of this International Standard is based on the following documents:
Draft Report on voting
55/1938/CDV 55/1974/RVC
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 60851 series, published under the general title Winding wires – Test
methods, 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.
IMPORTANT – The "colour inside" logo on the cover page of this document 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 60851 forms an element of a series of standards, which deals with insulated
wires used for windings in electrical equipment. The series has three groups describing:
a) winding wires − Test methods (IEC 60851);
b) specifications for particular types of winding wires (IEC 60317);
c) packaging of winding wires (IEC 60264).

– 8 – IEC 60851-3:2023 RLV © IEC 2023
WINDING WIRES – TEST METHODS –

Part 3: Mechanical properties
1 Scope
This part of IEC 60851 specifies the following test methods for winding wires:
– Test 6: Elongation;
– Test 7: Springiness;
– Test 8: Flexibility and adherence;
– Test 11: Resistance to abrasion;
– Test 18: Heat bonding.
For definitions, general notes on test methods and the complete series of test methods for
winding wires, IEC 60851-1 applies. This document also provides recommended friction test
methods in Annex B.
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 60851-1, Winding wires – Test methods – Part 1: General
IEC 60851-2:19962009, Winding wires – Test methods – Part 2: Determination of dimensions
IEC 60851-2:2009/AMD1:2015
IEC 60851-2:2009/AMD2:2019
ISO 178:20012019, Plastics – Determination of flexural properties
Amendment 1:2004
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 Test 6: Elongation
4.1 Elongation at fracture
Elongation is the increase in length expressed as a percentage of the original length.

A straight piece of wire shall be elongated to the point of fracture of the conductor at a rate of
(5 ± 1) mm/s with an elongation tester or with tensile testing equipment with a free measuring
length of between 200 mm and 250 mm. The linear increase at fracture shall be calculated as
a percentage of the free measuring length.
Three specimens shall be tested. The three single values shall be reported. The mean value
represents elongation at fracture.
4.2 Tensile strength
Tensile strength is the ratio of the force at fracture to initial cross-section.
A straight piece of wire shall be elongated to the point of fracture of the conductor at a rate of
(5 ± 1) mm/s with tensile testing equipment with a free measuring length of between 200 mm
and 250 mm and which records the force at fracture.
Three specimens shall be tested. The initial cross-section and the three single values of the
force at fracture shall be reported. The mean value of the ratio of the force at fracture and the
initial cross-section represents the tensile strength.
5 Test 7: Springiness
5.1 General
Springiness is the recoil measured in degrees after the wire is wound in the form of a helical
coil or bent through an angle.
5.2 Round wire with a nominal conductor diameter from 0,080 mm up to
and including 1,600 mm
5.2.1 Principle
A straight piece of wire is wound five times around a mandrel with a diameter and under a
tension applied to the wire as specified in the relevant standard. The reading of the angle by
which the end of the five turns recoils is the measure of springiness.
5.2.2 Equipment
Figure 1 shows an example of the test equipment with details of the mandrel given in Figure 2
and Table 1. Figure 2 indicates a helical groove, which may be used to facilitate winding. The
provision of this groove, however, is not mandatory. The dial is marked with 72 equally spaced
divisions so that with five turns of the wire the reading corresponds to the number of degrees
that each turn springs back.
– 10 – IEC 60851-3:2023 RLV © IEC 2023

Key
1 mandrel
2 dial
3 locking device
4 locking device
5 base-plate
6 mandrel-fixing screw
Figure 1 – Test equipment to determine springiness

Key
1 7 threads
2 part X enlarged
Figure 2 – Construction and details of the mandrel (see Table 1)

Table 1 – Mandrels for springiness
a b
Mandrel diameter Dimensions
mm mm
a b c d e f
5 6,0 7,5 32 0,30 0,05 0,13
7 6,0 9,0 34 0,40 0,07 0,18
10 6,0 9,0 34 0,60 0,10 0,25
12,5 6,0 9,0 40 0,80 0,14 0,35

19 10,0 11,0 45 1,20 0,20 0,50
25 12,5 12,5 45 2,00 0,28 0,70
37,5 12,5 14,5 47 2,40 0,40 1,00
50 12,5 17,5 50 3,00 0,80 2,00
a
At the bottom of the groove, if provided.
b
See Figure 2.
5.2.3 Procedure
The specified mandrel shall be mounted and locked in position with its axis horizontal and with
the slot or hole for fastening the wire corresponding with the zero of the dial. The mandrel shall
be dusted with powdered talc (French chalk) to prevent the wire clinging to the mandrel.
A tension shall be applied to a straight piece of wire of about 1 m in length by attaching the
specified load to one end of the wire. The handle to rotate the mandrel shall be unlatched. The
other end of the wire shall be inserted into the slot or hole so that sufficient wire projects on the
other side of the mandrel and the wire is in firm contact with the mandrel. The weight shall be
slowly lowered with the wire suspended vertically below the mandrel and with the dial zero and
the slot or hole pointing downwards.
With the free end of the wire being held securely, the mandrel shall be rotated for five complete
turns counterclockwise (looking at the face of the dial) and further until the zero on the dial is
vertically upwards. The handle shall then be latched in this position. The load shall be removed
while the wire is held in position, and the wire shall then be cut about 25 mm beyond the end
of the fifth turn. This end of the wire shall be bent into a vertical position in line with the dial
zero to act as a pointer.
A pencil or similar tool shall be placed to the left of this end of the wire to prevent any sudden
springback. The coil shall then be allowed to unwind slowly and without jerking.
NOTE If the wire springs back suddenly, it is possible to obtain erroneous results may be obtained.
The mandrel and the dial shall then be unlatched and rotated clockwise to bring the pointer
back into a vertical position. The springback angle is equal to the reading on the dial in line with
the pointer. With very springy wires, the pointer may recoil more than one complete revolution.
If this is the case, 72 has to shall be added to the dial reading for each complete revolution of
recoil.
Three specimens shall be tested. The three single values shall be reported. The mean value
represents springiness.
– 12 – IEC 60851-3:2023 RLV © IEC 2023
5.3 Round wire with a nominal conductor diameter over 1,600 mm and rectangular
wire
5.3.1 Principle
A straight piece of wire shall be bent through an angle of 30°. After removing the force, the
reading of the angle by which the wire springs back is the measure of springiness.
5.3.2 Equipment
Figure 3 shows an example of the test equipment basically consisting of two jaws, one of which
is fixed (2) and one is movable (1), and a sector graduated in degrees (5) with the 0° to 10°
sector of the scale graduated in 0,5° increments. The graduated sector is an arc placed in a
plane at 90° to the clamp faces. Its centre is located at the outer edge of the fixed jaw (3). The
lever arm with its fulcrum placed at the centre of the arc can move over the graduated sector in
the vertical plane.
The lever arm shall have a pointer or marker to provide a proper reading of the springback
angle. On the lever arm with approximately 305 mm length scaled off in millimetres with the
origin at the centre of the arc, is a slider (4) with a knife edge.

Dimensions in millimetres
Key
1 moveable jaw
2 fixed jaw
3 centre of graduated sector
4 slider
5 graduated sector
6 wire specimen
7 springback
Figure 3 – Test equipment to determine springiness
5.3.3 Specimen
A wire sample of at least 1 200 mm in length shall be removed from the spool with as little
bending of the wire as possible. It shall be straightened by hand and cut into three pieces each
of 400 mm length. Elongation by tools shall not be used. Unnecessary bending shall be avoided
to minimize work hardening.
5.3.4 Procedure
The conductor diameter or thickness, multiplied by 40, determines the position of the slider on
the lever arm. The specimen shall be tightened between the jaws with a force just sufficient to
prevent slipping. The specimen shall be tightened in such a position as to allow bending the
wire in the same direction as it was wound on the spool. The free end of the specimen shall
exceed the slider knife edge by (12 ± 2) mm.

– 14 – IEC 60851-3:2023 RLV © IEC 2023
By means of the lever arm, starting at the initial position (the 30° scale mark, position 1), the
wire shall be bent for 30° (the 0° scale mark, position 2). The total bending shall take between
2 s and 5 s. The specimen shall be held in this position for not more than 2 s and then returned
in the reverse direction at the same angular rate at which it was bent, until the slider knife edge
moves away from the wire specimen. The lever arm shall be raised again until the slider knife
edge just contacts the wire specimen without bending it. In this position, the springback angle
equals the reading on the scale of the graduated sector in line with the pointer on the lever arm
(position 3).
Three specimens shall be tested. The single All three values shall be reported. The mean value
represents springiness.
6 Test 8: Flexibility and adherence
6.1 General
Flexibility and adherence reflect the potential of the wire to withstand stretching, winding,
bending or twisting without showing cracks or loss of adhesion of the insulation.
6.2 Mandrel winding test
6.2.1 Round wire
6.2.1.1 General
A straight piece of wire shall be wound for 10 continuous and adjacent turns around a polished
mandrel of the diameter given in the relevant standard. The mandrel shall be rotated with a rate
of 1 r/s to 3 r/s with a tension applied to the wire that is just sufficient to keep it in contact with
the mandrel. Elongating or twisting the wire shall be avoided. Any suitable equipment shall be
used.
6.2.1.2 Enamelled round wire with a nominal conductor diameter up to and including
1,600 mm
If the relevant standard calls for pre-stretching before winding, the wire shall be elongated
according to Clause 4 to the specified percentage. After winding, the specimen shall be
examined for cracks with the magnification as given in Table 2.
Table 2 – Magnification to detect cracks
a
Nominal conductor diameter
Magnification
mm
Over Up to and including
– 0,040 10 to 15 times
0,040 0,500 6 to 10 times
0,500 1,600 1 to 6 times
a
One times magnification expresses normal vision.

Three specimens shall be tested. Any cracks detected shall be reported.
6.2.1.3 Fibre covered round wire
After winding, the specimen shall be examined for exposure of the bare conductor with normal
vision or with a magnification of up to six times.
Three specimens shall be tested. Exposure of the bare conductor shall be reported.

6.2.1.4 Fibre covered enamelled round wire
After winding, the specimen shall be examined for exposure of the bare conductor or underlying
coating with normal vision or with a magnification of up to six times.
Three specimens shall be tested. Exposure of the bare conductor or the underlying coating
shall be reported.
6.2.1.5 Tape wrapped round wire
After winding, the specimen shall be examined for exposure of the bare conductor or
delamination with normal vision or with a magnification of up to six times.
Three specimens shall be tested. Exposure of the bare conductor or any delamination shall be
reported.
6.2.2 Rectangular wire
A straight piece of wire approximately 400 mm in length shall be bent through 180° round a
polished mandrel of the diameter given in the relevant standard in two directions to form an
elongated S-shape. The straight part between the U-shape bends shall be at least 150 mm.
Care should be taken to ensure that the specimen does not buckle or depart from a uniform
bend. A suitable apparatus is shown in Figure 4.
After bending, the insulation shall be examined for cracks in the case of enamelled wire, for
exposure of the bare conductor or underlying coating in the case of fibre covered wire and
for exposure of the bare conductor and delamination in the case of tape wrapped wire under a
magnification of six to ten times.
Six specimens shall be bent, three flatwise (on the thickness) and three edgewise (on the width).
If the wire shows cracks or delamination, exposure of the bare conductor or underlying coating,
whichever is applicable, this shall be reported.

– 16 – IEC 60851-3:2023 RLV © IEC 2023

Key
1 mandrel
2 mandrel clamping collar
3 winding nut
4 lever
5 lever
6 ball bearing
7 specimen
8 support
Figure 4 – Test equipment for mandrel winding test
6.2.3 Covered bunched wire
A straight piece of wire shall be wound for ten continuous turns around a polished mandrel of
the diameter given in the relevant standard and under a tension given in IEC 60851-2:2009,
3.2.5.3. Care should be taken not to twist the specimen for each revolution.
After winding, the specimen shall be examined by normal vision for openings in the covering.
One specimen shall be tested. If the wire does not show the required degree of closeness of
the covering, this shall be reported.
6.3 Stretching test (applicable to enamelled round wire with a nominal conductor
diameter over 1,600 mm)
A straight piece of wire shall be elongated according to Clause 4 to the percentage specified in
the relevant standard. After elongation, the specimen shall be examined for cracks or loss of
adhesion with normal vision or with a magnification of up to six times.
Three specimens shall be tested. If the wire shows cracks and/or loss of adhesion, this shall be
reported.
6.4 Jerk test (applicable to enamelled round wire with a nominal conductor diameter
up to and including 1,000 mm)
A straight piece of wire shall be rapidly stretched to the breaking point with test equipment as
shown in Figure 5. A free measuring length of between 200 mm and 250 mm shall be provided.
After stretching, the specimen shall be examined for cracks or loss of adhesion under a
magnification as given in Table 2. A distance of 2 mm from the broken ends shall be
disregarded.
Three specimens shall be tested. If the wire shows cracks and/or loss of adhesion, this shall be
reported.
Key
1 wedge grips (clamps)
2 fixed jaw set
3 lever arm
4 adjustable stop
5 specimen
6 specified elongation
Figure 5 – Test equipment for jerk test
6.5 Peel test (applicable to enamelled round wire with a nominal conductor diameter
over 1,000 mm)
A straight piece of wire shall be placed in the test equipment shown in Figure 6 consisting of
two fixing devices 500 mm apart on the same axis. One of these is free to rotate. The other is
not but can be displaced axially and is loaded according to Table 3 to apply a tension to the
rotating wire.
– 18 – IEC 60851-3:2023 RLV © IEC 2023

Key
1 specimen
2 rotary clamp
3 fixed clamp
4 load
Figure 6 – Test equipment for peel test
Table 3 – Load for peel test
Nominal conductor diameter Load
mm N
Over Up to and including
1,000 1,400 25
1,400 1,800 40
1,800 2,240 60
2,240 2,800 100
2,800 3,550 160
3,550 4,500 250
4,500 5,000 400
By means of a scraper as shown in Figure 7, the coating shall be removed on opposite sides of
the wire and along the wire axis down to the bare conductor as shown in Figure 8. The pressure
on the scraper shall be sufficient to remove the coating and leave a clean smooth surface at
the coating/conductor interface without scraping off a significant quantity of conductor material.
The removal of the coating shall commence about 10 mm from the fixing devices. The rotating
device shall be driven at a speed of between 60 r/min and 100 r/min until the number of
revolutions R as specified in the relevant standard has been reached.
After peeling and rotating, the specimen shall be examined for loss of adhesion. If the coating
can be removed from the wire without difficulty (for example with the thumbnail), it shall be
considered to have lost its adhesion even if it has not become completely detached from the
wire.
One specimen shall be tested. If loss of adhesion is observed, this shall be reported.

Figure 7 – Scraper
Figure 8 – Cross-section of the wire after removal of the coating
6.6 Adherence test
6.6.1 General
A straight piece of wire of about 300 mm length shall be elongated in accordance with Clause 4
to the percentage specified in the relevant standard.
6.6.2 Enamelled rectangular wire
Before elongation, the coating shall be cut circumferentially through to the conductor at a point
approximately in the centre of the measured length. After elongation, the specimen shall be
examined for loss of adhesion.
One specimen shall be tested. If loss of adhesion is observed, as determined by longitudinal
measurement from the cut, it shall be reported. If so, the length of loss of adhesion shall be
measured in one direction from the cut. The maximum value observed shall be reported after
examining all sides of the specimen, under a magnification of six to ten times.
6.6.3 Impregnated fibre covered round and rectangular wire
Before elongation, the insulation shall be cut circumferentially at two places 100 mm apart in
the centre of the wire specimen through to the conductor. After elongation, the specimen shall
be examined for loss of adhesion under a magnification of six to ten times.
One specimen shall be tested. If loss of adhesion is observed according to the relevant
specification, as determined by longitudinal measurement in one direction from the cut, it shall
be reported. The maximum value observed shall be reported after examining all sides of the
specimen, under a magnification of six to ten times.
6.6.4 Fibre covered enamelled round and rectangular wire
Before elongation, the insulation shall be cut circumferentially at two places 100 mm apart in
the centre of the wire specimen through to the conductor. After elongation, the specimen shall
be examined for loss of adhesion under a magnification of six to ten times.
One specimen shall be tested. If loss of adhesion is observed according to the relevant
specification, as determined by longitudinal measurement in one direction from the cut, it shall
be reported. The maximum value observed shall be reported after examining all sides of the
specimen, under a magnification of six to ten times.

– 20 – IEC 60851-3:2023 RLV © IEC 2023
6.6.5 Tape-wrapped round and rectangular wire (for adhesive tape only)
Before elongation, the insulation shall be cut circumferentially through to the conductor at a
point approximately in the centre of the measured length. After elongation, the specimen shall
be examined for loss of adhesion under a magnification of six to ten times. One specimen shall
be tested. The maximum value observed shall be reported after examining all sides of the
specimen, under a magnification of six to ten times. If loss of adhesion is observed according
to the relevant specification, as determined by longitudinal measurement in one direction from
the cut, it shall be reported.
7 Test 11: Resistance to abrasion (applicable to en
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