IEC 61238-1-2:2018

IEC 61238-1-2 ®
Edition 1.0 2018-05
INTERNATIONAL
STANDARD
Compression and mechanical connectors for power cables –
Part 1-2: Test methods and requirements for insulation piercing connectors for
power cables for rated voltages up to 1 kV (U = 1,2 kV) tested on insulated
m
conductors
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IEC 61238-1-2 ®
Edition 1.0 2018-05
INTERNATIONAL
STANDARD
Compression and mechanical connectors for power cables –

Part 1-2: Test methods and requirements for insulation piercing connectors for

power cables for rated voltages up to 1 kV (U = 1,2 kV) tested on insulated

m
conductors
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.060.20 ISBN 978-2-8322-5646-6

– 2 – IEC 61238-1-2:2018 © IEC 2018
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 8
4 Symbols . 10
5 General . 11
5.1 Definition of classes . 11
5.2 Cable . 11
5.3 Connectors and installation procedure . 12
5.4 Range of approval. 12
6 Electrical tests . 13
6.1 Installation . 13
6.1.1 General . 13
6.1.2 Through connectors . 13
6.1.3 Branch connectors . 14
6.2 Measurements . 14
6.2.1 General . 14
6.2.2 Electrical resistance measurements . 14
6.2.3 Temperature measurements . 15
6.3 Heat cycling test . 16
6.3.1 General . 16
6.3.2 First heat cycle . 16
6.3.3 Second heat cycle . 16
6.3.4 Subsequent heat cycles . 18
6.4 Short-circuit test for connectors according to Class A . 18
6.5 Assessment of results . 19
6.6 Requirements . 19
6.7 Examples of electrical test loop configurations and associated parameters . 20
7 Mechanical test . 24
7.1 General . 24
7.2 Method . 24
7.3 Requirements . 24
8 Test reports . 24
8.1 General . 24
8.2 Electrical tests . 24
8.3 Mechanical test . 25
Annex A (normative) Equalizers and their preparation . 26
A.1 Requirements for equalizers . 26
A.2 Recommendations for welding equalizers . 26
Annex B (normative) Measurements . 28
B.1 Potential measuring positions for typical connectors . 28
B.2 Temperature measurement . 28
B.3 Equivalent conductor resistance . 28
Annex C (informative) Recommendations to decrease uncertainties of measurement . 29
C.1 Handling the test loop . 29

C.2 Measurements, instruments and readings . 29
Annex D (normative) Calculation of adiabatic short-circuit current . 30
Annex E (informative) Determination of the value of the short-circuit current . 31
Annex F (normative) Calculation method . 32
F.1 General . 32
F.2 Measurements made . 32
F.3 Connector resistance factor k . 32
F.4 Initial scatter δ . 33
F.5 Mean scatter β . 33
F.6 Change in resistance factor of each connector . 35
F.6.1 General . 35
F.6.2 Line of best fit . 35
F.6.3 Confidence interval δ . 35
i
F.6.4 Change in resistance factor D . 36
F.7 Resistance factor ratio λ. 36
F.8 Maximum temperatures θ . 36
max
Annex G (informative) Explanation on assessment of results of electrical tests on

connectors . 37
G.1 History . 37
G.2 Short examination of the assessment methods of IEC 61238-1 compared
with the Italian standard CEI 20-28 and the British standard BS 4579-3 . 37
G.3 The IEC 61238-1 method of assessing test results . 38
Annex H (informative) Tests on multicore connectors . 40
H.1 Principle . 40
H.1.1 Electrical tests . 40
H.1.2 Mechanical tests . 40
H.2 Test recommendations for electrical tests based on test experience in the
UK and in France . 40
H.2.1 General . 40
H.2.2 Measurement . 41
H.2.3 Heat cycling test . 41
H.2.4 Short-circuit test (only for Class A) . 41
H.2.5 Results evaluation . 42
H.3 Test recommendations for electrical tests based on German standard
DIN VDE 0220- 3 . 43
H.3.1 General . 43
H.3.2 Test setup for electrical test . 44
H.3.3 Resistance assessment branches of the test setup . 45
H.3.4 Temperature measurement in a separate test branch during the first
and second heat-cycle . 45
H.3.5 Interconnection of terminals for heat-cycling . 47
H.3.6 Short-circuit tests . 49
H.3.7 Assessment of resistance-values R . 51
j
H.3.8 Optional dielectric strength test after the electrical test . 52
Annex I (informative) Load pick-up tests . 54
Bibliography . 55

Figure 1 – Position of thermocouples . 15
Figure 2 – Example of second heat cycle profile . 17

– 4 – IEC 61238-1-2:2018 © IEC 2018
Figure 3 – Typical electrical test loop for through connectors installed on insulated
conductors . 21
Figure 4 – Typical electrical test loop for branch connectors installed on insulated
conductors . 22
Figure 5 – Typical cases of resistance measurements . 23
Figure A.1 – Preparation of equalizers . 27
Figure E.1 – Determination of equivalent RMS value of current during the short-circuit test . 31
Figure F.1 – Graphic example of assessment of a Class A individual connector . 34
Figure H.1 – Test loops for through connectors . 42
Figure H.2 – Test loops for branch connectors . 43
Figure H.3 – Example of test setup for multicore branch connectors on a four-core
cable consisting of several test branches . 45
Figure H.4 – Example of circuit schematic for heat-cycling of multicore branch
connectors main to branch, e.g. 150/150, 150/120 or 150/95 in the case of four-core
cables . 48
Figure H.5 – Example of circuit schematic for heat-cycling of multicore branch
connectors main to branch, e.g. 150/70 and smaller in the case of four-core cables . 49
Figure H.6 – Example of circuit schematic in the case of four-core cable connector
tests for passing short circuits on main through adjacent Phases L2–L3 with opposite
current flow . 50
Figure H.7 – Example of circuit schematic in the case of four-core cable branch connector
tests for short circuit test from main to branch through adjacent Phases L4–L1 with
opposite current flow . 51

Table 1 – Minimum period of temperature stability . 16
Table 2 – Electrical resistance measurements during the electrical test . 18
Table 3 –Electrical test requirements . 20
Table 4 – Selection of tensile force withstand values for the mechanical test . 24
Table D.1 – Material properties . 30
Table G.1 – Summary of assessed behaviour of a tested connector . 39
Table I.1 – Minimum load pick-up. 54

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
COMPRESSION AND MECHANICAL
CONNECTORS FOR POWER CABLES –
Part 1-2: Test methods and requirements for insulation piercing
connectors for power cables for rated voltages up to 1 kV
(U = 1,2 kV) tested on insulated conductors
m
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
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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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6) All users should ensure that they have the latest edition of this publication.
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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 61238-1-2 has been prepared by IEC technical committee 20:
Electric cables.
This first edition, together with IEC 61238-1-1 and IEC 61238-1-3, cancels and replaces
IEC 61238-1:2003.
This edition includes the following significant technical changes with respect to
IEC 61238-1:2003:
a) The scope has been widened to cover connectors for conductors from 10 mm down to
2 2 2
2,5 mm and has been limited to 300 mm for copper conductors and 500 mm for
aluminium conductors because test experience and applications for IPC are rare for
conductors of larger cross-sectional areas.

– 6 – IEC 61238-1-2:2018 © IEC 2018
b) A new mechanical class has been introduced to satisfy the demand for connectors
subjected to no mechanical force.
c) The electrical test method has been updated in order to take into consideration the
temperature of the insulated reference conductors.
d) For the short-circuit test, the method of calculation and requirements have been updated.
e) For the mechanical test, the methods and requirements have been updated.
f) Different test proposals for multicore connector testing have been introduced.
g) A test proposal for pre-conditioning using live load pickup for insulation piercing
connectors has been introduced.
The text of this International Standard is based on the following documents:
FDIS Report on voting
20/1789/FDIS 20/1804/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.
A list of all parts in the IEC 61238 series, published under the general title Compression and
mechanical connectors for power 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.
A bilingual version of this publication may be issued at a later date.

INTRODUCTION
The IEC 61238 series has been divided into the following parts:
Part 1-1: Test methods and requirements for compression and mechanical connectors for
power cables for rated voltages up to 1 kV (U = 1,2 kV) tested on non-insulated
m
conductors
Part 1-2: Test methods and requirements for insulation piercing connectors for power
cables for rated voltages up to 1 kV (U = 1,2 kV) tested on insulated conductors
m
Part 1-3: Test methods and requirements for compression and mechanical connectors for
power cables for rated voltages above 1 kV (U = 1,2 kV) up to 30 kV
m
(U = 36 kV) tested on non-insulated conductors
m
This Part 1-2 of IEC 61238-1 deals with type tests for insulation piercing connectors for use
on copper or aluminium conductors of power cables for rated voltages up to
1 kV (U = 1,2 kV).
m
When a design of connector meets the requirements of this document, then it is expected that
in service:
a) the resistance of the connection will remain stable within specified limits;
b) the temperature of the connector will be of the same order or less than that of the
insulated conductor during current heating;
c) if the intended use demands it, application of short-circuit currents will not affect a) and b);
d) independently from the electrical performance, conforming axial tensile strength will
ensure an acceptable mechanical performance for the connections to the cable
conductors, when applicable.
It should be stressed that, although the object of the electrical and mechanical tests specified
in this document is to prove the suitability of connectors for most operating conditions, they do
not necessarily apply to situations where a connector may be raised to a high temperature by
virtue of connection to a highly rated plant, to corrosive conditions, where the connector is
subjected to external mechanical stresses such as excessive vibration, shock and large
displacement after installation, where the connector is exposed to low temperature during
assembly or where the connector is installed in live conditions. In these instances, the tests in
this document may need to be supplemented by special tests agreed between supplier and
purchaser.
This document does not invalidate existing approvals of products achieved on the basis of
national standards and specifications and/or the demonstration of satisfactory service
performance. However, products approved according to such national standards or
specifications cannot directly claim approval to this document.
Once successfully completed, these tests are not repeated unless changes are made in
material, manufacturing process and design which might adversely change the connector
performance characteristics.
– 8 – IEC 61238-1-2:2018 © IEC 2018
COMPRESSION AND MECHANICAL
CONNECTORS FOR POWER CABLES –
Part 1-2: Test methods and requirements for insulation piercing
connectors for power cables for rated voltages up to 1 kV
(U = 1,2 kV) tested on insulated conductors
m
1 Scope
This part of IEC 61238 applies to insulation piercing connectors for power cables for rated
voltages up to 1 kV (U = 1,2 kV), for example according to IEC 60502-1 or other buried
m
cables and cables installed in buildings, having
a) conductors complying with IEC 60228 having nominal cross-sectional areas between
2 2 2 2
2,5 mm and 300 mm for copper and between 16 mm and 500 mm for aluminium,
b) a maximum continuous cable temperature not exceeding the insulation material properties.
This document is not applicable to connectors for overhead line conductors nor to connectors
with a sliding contact.
The object of this document is to define the type test methods and requirements, which apply
to insulation piercing connectors for power cables with copper or aluminium conductors. The
reference method is to perform the tests on unused insulated conductors.
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 60050-461, International Electrotechnical Vocabulary – Part 461: Electric cables
(available at http://www.electropedia.org)
IEC 60228, Conductors of insulated cables
IEC 60493-1, Guide for the statistical analysis of ageing test data – Part 1: Methods based on
mean values of normally distributed test results
IEC 60949:1988, Calculation of thermally permissible short-circuit currents, taking into
account non-adiabatic heating effects
IEC 60949:1988/AMD1:2008
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-461 and the
following 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
3.1
connector
device for connecting a conductor to an equipment terminal or for connecting two
or more conductors to each other
[SOURCE: IEC 60050-461:2008, 461-17-03, modified – the definition has been revised.]
3.2
through connector
device for connecting two consecutive lengths of conductor together
[SOURCE: IEC 60050-461:2008, 461-17-04, modified – the term "joint ferrule" has been
deleted and the definition revised.]
3.3
branch connector
device for connecting a branch conductor to a main conductor at an intermediate point on the
latter
[SOURCE: IEC 60050-461:2008, 461-17-05, modified – the term "branch ferrule" has been
deleted and in the definition "metallic" has been deleted.]
3.4
reference conductor
length of unjointed insulated conductor or conductor with the insulation rebuilt, which is
included in the test loop and which enables the reference temperature and reference
resistance to be determined
3.5
equalizer
arrangement used in the test loop to ensure a point of equipotential and uniform current
distribution in a stranded conductor
3.6
compression jointing
method of securing a connector to a conductor by using a special tool to produce permanent
deformation of the connector and the conductor
3.7
mechanical jointing
method of securing a connector to a conductor, for example by means of a bolt or screw
acting on the latter or by alternative methods
3.8
median connector
connector which during the first heat cycle records the third highest temperature of the six
connectors in the test loop
3.9
insulation piercing connector
IPC
connector in which electrical contact with the conductor is made by metallic protrusions which
pierce the insulation of the cable core
[SOURCE: IEC 60050-461:2008, 461-11-08]

– 10 – IEC 61238-1-2:2018 © IEC 2018
3.10
insulation piercing jointing
method of securing an IPC to an insulated conductor by piercing, boring through, cutting
through, or making ineffective in some other manner the insulation of at least one cable
conductor without previous stripping during installation
Note 1 to entry: The temperatures are no longer limited by the conductor but by the cable insulation.
Note 2 to entry: This method may allow live line working if the connector provides sufficient insulation properties.
Safety requirements for live working are not covered by this document.
3.11
conductor
part of a cable which has the specific function of carrying current
[SOURCE: IEC 60050-461:2008, 461-01-01]
3.12
family of connectors
group of connectors of a manufacturer to be considered of the same design criteria, the same
material characteristic and the same installation procedure
4 Symbols
A
nominal cross-sectional area of the conductor
D change in the resistance factor of the connector
I
direct current flowing through a connection during resistance measurement
I equivalent RMS short-circuit current
RMS
I
alternating current necessary to maintain the insulated reference conductor at its
N
equilibrium temperature
I
direct current flowing through the insulated reference conductor/conductors
r
during resistance measurement
k
connector resistance factor: ratio of the resistance of a connector to that of the
resistance of the equivalent length of the reference conductor
k
initial connector resistance factor: ratio of the resistance of a connector to that of
the resistance of the equivalent length of the reference conductor at cycle no. 0
l , l , l
lengths of each connector assembly associated with the measurement positions
a b j
in the test setup after installation
l
length of the insulated reference conductor between measurement positions
r
R measured resistance value of connector/insulated conductor installation under an
electrical test corrected to 20 °C
R measured resistance value of the insulated reference conductor corrected to
r
20 °C
R length related calculated resistance value of a connector under an electrical test
j
corrected to 20 °C
t heating time
t
time necessary for the connectors and the insulated reference conductor to cool
to a value equal to or less than 35 °C
U potential difference between measurement positions while current I is applied
U potential difference between measurement positions on an insulated reference
r
conductor while current I is applied
r
temperature coefficient of resistance at 20 °C
α
mean scatter of the connector resistance factors
β
initial scatter of the connector resistance factors
δ
resistance factor ratio: the actual resistance factor of the connector at each
λ
measurement stage divided by its initial resistance factor
temperature of a connector
θ
θ maximum temperature recorded on a connector over the total period of test
max
during heat cycling
θ temperature of the main insulated reference conductor determined in the first
R
heat cycle
θ temperature of the branch insulated reference conductor determined in the first
Rb
heat cycle
θ temperature of the related insulated reference conductor at the moment of
ref
measuring θ
max
5 General
5.1 Definition of classes
Although it is not possible to define precisely the service conditions for all applications, the
following requirements have been identified.
a) Electrical requirements:
Class A
These are connectors intended for electricity distribution or industrial networks in which
they can be subjected to short-circuits of relatively high intensity and duration. As a
consequence, Class A connectors are suitable for the majority of applications.
Class B
These are connectors for networks in which overloads or short-circuits are rapidly cleared
by the installed protective devices, for example, fast-acting fuses.
b) Mechanical requirements:
Class 0
Connectors subjected to practically no mechanical pull-out force. These are, for example,
connectors inside switchgear where the cable or conductors are secured or anchored.
Class 1
Connectors subjected to a mechanical pull-out force related to the conductor nominal
cross-sectional area and material (according to Table 4). These are, for example,
connectors for underground cable joints.
Hence, the four classes correspond to the following tests:
Class A: heat cycling and short-circuit tests;
Class B: heat cycling test only;
Class 0: no mechanical test;
Class 1: mechanical test.
5.2 Cable
The following information shall be recorded in the test report:
– conductor material;
– nominal cross-sectional area, dimensions and shape;

– 12 – IEC 61238-1-2:2018 © IEC 2018
– detail of conductor construction shall be given when known, or can be determined by
inspection, for example:
• class according to IEC 60228 (solid, stranded and flexible);
• compacted or non-compacted for stranded conductor;
• number and arrangement of strands;
• type of plating, if applicable;
• type of impregnation, water blocking, etc., if applicable;
– cable specification, including insulation type and thickness, etc.;
– conditioning of the cable if applied prior to testing.
5.3 Connectors and installation procedure
The following information shall be recorded in the test report:
– the assembly method or the installation instruction that is to be used;
– tooling and any necessary setting;
– identification of the connector, for example name of the supplier, drawing, reference
number, type;
– installation temperature and, if applicable, other treatment during installation, for example
live load pickup (see Annex I).
5.4 Range of approval
In general, tests made on one type of insulation piercing connector, conductor and insulation
combination apply to that arrangement only. However, to limit the number of tests the
following is permitted:
– a connector which can be used on stranded round conductors is approved for this type if
satisfactory results are obtained on a compacted round conductor;
– a connector which covers a range of consecutive cross-sectional areas shall be approved,
if satisfactory results are obtained on the smallest and the largest cross-sectional area;
– if a manufacturer can clearly demonstrate that common and relevant connector design
criteria were used for a family of connectors, conformity to this document is achieved by
successfully testing the largest, the smallest and two intermediate connector sizes;
exception no.1: for a family of connectors consisting of five sizes, only the largest
connector, the smallest connector, and one connector of a representative intermediate
size need to be tested;
exception no.2: for a family of connectors consisting of four sizes or less, only the
largest connector and the smallest connector need to be tested;
– for connectors where one or both sides are designed for a range of cross-sectional areas,
and a common clamping or crimping arrangement serves for the connection of the
different cross-sectional areas, then mechanical tests on conductors with the largest and
smallest cross-sectional areas shall be carried out according to Clause 7 for connectors
according to Class 1;
– if conformity to this document is achieved by successfully testing a mechanical connector
on round stranded aluminium conductors, this type test approval can be applied to solid
aluminium conductors of the same cross-sectional area(s);
– if conformity to this document is achieved by successfully testing a connector on a
conductor with water blocking, approval is achieved for the same conductor without any
water blocking but not for the same conductor with different types of water blocking.

6 Electrical tests
6.1 Installation
6.1.1 General
All insulated conductors of the same nominal cross-sectional area in the test loop shall be
taken from the same insulated conductor length.
For each series of tests, six connectors shall be installed on insulated conductors in
accordance with the manufacturer’s instructions.
At a distance not less than 100 mm to the entrance of the connector, the insulation can be
removed to prepare equalizers according to Annex A.
Reference conductor(s) with the insulation retained shall also be included in the test loop.
For stranded conductors, potential differences between the strands at potential measuring
positions can cause errors in measuring electrical resistance. Equalizers according to
Annex A shall be used to overcome this problem and to ensure uniform current distribution in
the reference conductor and between connectors at the equalizer positions. The
recommended method is to prepare equalizers on the test loop before installing connectors.
The test loop shall be installed in a location where the air is calm.
The ambient temperature of the test location shall be between 15 °C and 30 °C.
For assembly of the test objects, the temperature shall be (23 ± 3) °C. The test objects should
be stored for a sufficient time to reach the required installation temperature.
In the case of solid conductors, the potential measuring positions shall be as close as
possible to the connector in order to reduce l and l . A minimum distance of 10 mm shall be
a b
kept to the cable entrance of the IPC to avoid any influence on the IPC by cutting through the
cable insulation when setting the measuring position.
The test loop may be of any shape according to Figure 3 or Figure 4 provided that it is
arranged in such a way that there is no adverse effect from the floor, walls and ceiling, other
test loops and adjacent test branches.
To facilitate the short-circuit test for connectors according to Class A, the loop may be
disassembled as shown in Figure 3 b). In this case, the sectioning connections shall not
influence the temperatures of the test objects during heating.
Retightening of bolts or screws of the connectors under test is not permitted.
NOTE 1 Informative Annex H proposes electrical tests for multicore connectors. These tests are not
internationally recognized and subject to customer/manufacturer agreement.
NOTE 2 Informative Annex I gives recommendations to simulate loads (related to the cross sectional area) acting
during installation of an IPC while the cables are still in service. This test is done during the initial insertion of the
IPC in the test loop, before starting electric tests.
6.1.2 Through connectors
The test loop shown in Figure 3 indicates the dimensions that shall be used.

– 14 – IEC 61238-1-2:2018 © IEC 2018
6.1.3 Branch connectors
When the branch connector is intended for a branch nominal cross-sectional area equal to the
main, or a nominal cross-sectional area immediately above or below the main, it is treated as
a through connector between the main and the branch, and the test method for through
connectors and the test loop shown in Figure 3 c) are applicable. In other cases, the test loop
shall be as shown in Figure 4. Where a type of connector makes it necessary for the insulated
main conductor to be cut, that part of the connector which acts as a through connector, shall

also be tested as for through connectors.
6.2 Measurements
6.2.1 General
Measurements shall be made at stages throughout the test according to Table 2.
NOTE Recommendations to decrease uncertainties of measurements are given in Annex C.
6.2.2 Electrical resistance measurements
The resistance measurements shall be made under steady temperature conditions of both the
test loop and test location. The ambient temperature shall be between 15 °C and 30 °C.
The recommended method is to pass a direct current of up to 10 % of the estimated heat
cycling current, through the connectors and the insulated reference conductor, without
significantly increasing the temperature and to measure the potential difference between two
specific potential measuring positions. The ratio of potential difference and direct current is
the resistance between those two positions.
To decrease the uncertainty of the resistance measurement, it is recommended that the direct
current is adjusted to the same value throughout the electrical test.
For insulated branch conductors assembled in accordance with Figure 4, the whole of the
measuring current shall flow through that part of the connector whose potential difference is
being measured. Switches or disconnecting terminals may be provided for this purpose.
Thermoelectric voltages may affect the uncertainty of low resistance measurements (of the
order of 10 µΩ). If this is suspected, the recommended method is to take two resistance
measurements with the direct measuring current reversed between readings. The mean of the
two readings is then the actual resistance of the sample.
The potential measuring positions shall be as indicated in Figure 5 and Annex B. The various
lengths shall also be measured individually to enable the actual connector
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