IEC 62067:2001

IEC 62067
Edition 1.1 2006-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Power cables with extruded insulation and their accessories for rated voltages
above 150 kV (U = 170 kV) up to 500 kV (U = 550 kV) – Test methods
m m
and requirements
Câbles d'énergie à isolation extrudée et leurs accessoires pour des tensions
assignées supérieures à 150 kV (U = 170 kV) et jusqu'à 500 kV (U = 550 kV) –
m m
Méthodes et prescriptions d'essai

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IEC 62067
Edition 1.1 2006-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Power cables with extruded insulation and their accessories for rated voltages
above 150 kV (U = 170 kV) up to 500 kV (U = 550 kV) – Test methods
m m
and requirements
Câbles d'énergie à isolation extrudée et leurs accessoires pour des tensions
assignées supérieures à 150 kV (U = 170 kV) et jusqu'à 500 kV (U = 550 kV) –
m m
Méthodes et prescriptions d'essai

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CM
CODE PRIX
ICS 29.060.20 ISBN 2-8318-8539-6

62067 © IEC:2001+A1:2006 – 3 –
– 2 – 62067 © IEC:2001+A1:2006
CONTENTS
FOREWORD.4
INTRODUCTION.6
1 Scope.7
2 Normative references.7
3 Definitions .8
3.1 Definitions of dimensional values (thicknesses, cross-sections, etc.) .8
3.2 Definitions concerning the tests .8
4 Voltage designations and materials .9
4.1 Rated voltages .9
4.2 Cable insulating materials.9
4.3 Cable oversheathing materials .9
5 Precautions against water penetration in cables .10
6 Cable characteristics .10
7 Accessory characteristics.10
8 Test conditions .11
8.1 Ambient temperature .11
8.2 Frequency and waveform of power frequency test voltages .11
8.3 Waveform of lightning impulse test voltage .11
8.4 Waveform of switching impulse test voltage .11
8.5 Relationship of test voltages to rated voltages.11
9 Routine tests on cables and on the main insulation of prefabricated accessories .12
9.1 General .12
9.2 Partial discharge test .12
9.3 Voltage test .12
9.4 Electrical test on oversheath of the cable .13
10 Sample tests on cables.13
10.1 General .13
10.2 Frequency of tests .13
10.3 Repetition of tests.13
10.4 Conductor examination .13
10.5 Measurement of electrical resistance of conductor .14
10.6 Measurement of thickness of insulation and cable oversheath.14
10.7 Measurement of thickness of metallic sheath .15
10.8 Measurement of diameter .16
10.9 Hot set test for XLPE and EPR insulations .16
10.10 Measurement of capacitance .16
10.11 Measurement of density of HDPE insulation .16
10.12 Lightning impulse voltage test followed by a power frequency voltage test .16
11 Sample tests on accessories.17

62067 © IEC:2001+A1:2006 – 5 –
62067 © IEC:2001+A1:2006 – 3 –
12 Type tests on cable systems .17
12.1 General .17
12.2 Range of type approval .17
12.3 Summary of type tests .18
12.4 Electrical type tests on complete cable systems .18
12.5 Non-electrical type tests on cable components and on complete cable .22
13 Prequalification test of the cable system.25
13.1 Range of prequalification test approval .25
13.2 Prequalification test on complete cable system .26
14 Electrical tests after installation.27
14.1 DC voltage test of the oversheath .27
14.2 AC voltage test of the insulation.27

Annex A (normative) Rounding of numbers.34
Annex B (normative) Method of measuring resistivity of semi-conducting screens.35
Annex C (normative) Water penetration test .37
Annex D (normative) Tests of outer protection for buried joints .39

Bibliography .41

Figure B.1 – Preparation of samples for measurement of resistivity of conductor and
insulation screens .36
Figure C.1 – Schematic diagram of apparatus for water penetration test .38

Table 1 – Insulating compounds for cables .28
Table 2 – Tan δ requirements for insulating compounds for cables .28
Table 3 – Test voltages .28
Table 4 – Non-electrical type tests for insulating and oversheathing compounds
for cables.29
Table 5 – Test requirements for mechanical characteristics of insulating compounds
for cables (before and after ageing).30
Table 6 – Test requirements for mechanical characteristics of oversheathing
compounds for cables (before and after ageing) .31
Table 7 – Test requirements for particular characteristics of insulating compounds
for cables.32
Table 8 – Carbon black content of thermoplastic polyethylene oversheathing compounds
for cables.32
Table 9 – Test requirements for particular characteristics of PVC oversheathing
compounds for cables .33
Table 10 – AC test voltages after installation .33
Table D.1 – Impulse voltage tests.40

62067 © IEC:2001+A1:2006 – 7 –
– 4 – 62067 © IEC:2001+A1:2006
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
POWER CABLES WITH EXTRUDED INSULATION AND THEIR ACCESSORIES
FOR RATED VOLTAGES ABOVE 150 kV (U = 170 kV)
m
UP TO 500 kV (U = 550 kV) –
m
TEST METHODS AND REQUIREMENTS
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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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 62067 has been prepared by IEC technical committee 20: Electric
cables.
This consolidated version of IEC 62067 consists of the first edition (2001) [documents
20/482/FDIS and 20/489/RVD] and its amendment 1 (2006) [documents 20/784/FDIS and
20/802/RVD].
The technical content is therefore identical to the base edition and its amendment and has
been prepared for user convenience.
It bears the edition number 1.1.
A vertical line in the margin shows where the base publication has been modified by
amendment 1.
Annexes A, B, C and D form an integral part of this standard.

62067 © IEC:2001+A1:2006 – 9 –
62067 © IEC:2001+A1:2006 – 5 –
The committee has decided that the contents of the base publication and its amendments will
remain unchanged until the maintenance result 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.
62067 © IEC:2001+A1:2006 – 11 –
– 6 – 62067 © IEC:2001+A1:2006
INTRODUCTION
As a result of major developments in cable systems with extruded insulation for voltages above
150 kV, CIGRE Study Committee 21 set up Working Group (WG) 21.03 in 1990. The terms of
reference of WG 21.03 were "to prepare recommendations for electrical type tests, sample and
routine tests, based on extending IEC 60840 (1988) up to 400 kV and to make proposals for
prequalification/development tests which, as a minimum, should be performed ".
WG 21.03 reported that the extension of IEC 60840 to voltages above 150 kV needed extra
consideration because of the following factors:
– such cables form part of the backbone of the transmission system and, therefore, reliability
considerations are of the highest priority;
– these cables and their accessories operate with higher electrical stresses than cables up to
150 kV and, as a result, have a smaller safety margin with respect to the intrinsic
performance boundaries of the cable system;
– such cables and accessories have a thicker insulation wall than those up to 150 kV and, as
a result, are subjected to greater thermomechanical effects;
– the design and coordination of the cables and accessories become more difficult with
increasing system voltage levels.
The recommendations of the WG 21.03 were published in Electra No. 151 in December 1993
and taken into account by IEC in 1995 in the preparation of this standard for cable systems
with extruded insulation for voltages above 150 kV. IEC considered that this new standard
should also cover the 500 kV level. Thus, at its meeting in September 1996, CIGRE Study
Committee 21 set up a Task Force 21.18 to study the extension of the initial recommendations
to the 500 kV level. The updated recommendations were cited in Electra No. 193 in December
2000 and again taken into account by IEC in the preparation of this standard.
Compared with IEC 60840, first edition (1988), revised and published in 1999 as IEC 60840
edition 2, there is a major difference: CIGRE advised that, in order to gain some indication of
the long term reliability of a cable system, it is necessary to carry out a long term accelerated
ageing test. This test, known as the "prequalification test", is to be performed on the complete
system comprising the cable, joints and terminations in order to demonstrate the performance
of the system.
In addition, CIGRE WG 21.09, given the task to study tests after installation on high-voltage
extruded insulation cable systems, published its recommendations in Electra No 173 in August
1997. In the preparation of this International Standard, account has also been taken of these
recommendations which state, among others, that d.c. tests should be avoided on the main
insulation, as they are both ineffective and dangerous. On the other hand, d.c. tests are
recommended on the oversheath.
A list of relevant CIGRE references is given in the bibliography.

62067 © IEC:2001+A1:2006 – 13 –
62067 © IEC:2001+A1:2006 – 7 –
POWER CABLES WITH EXTRUDED INSULATION AND THEIR ACCESSORIES
FOR RATED VOLTAGES ABOVE 150 kV (U = 170 kV)
m
UP TO 500 kV (U = 550 kV) –
m
TEST METHODS AND REQUIREMENTS
1 Scope
This International Standard specifies test methods and requirements for power cable systems,
cables with extruded insulation and their accessories for fixed installations, for rated voltages
above 150 kV (U = 170 kV) up to and including 500 kV (U = 550 kV).
m m
The requirements apply to single-core cables and to their accessories for usual conditions of
installation and operation, but not to special cables and their accessories, such as submarine
cables, for which modifications to the standard tests may be necessary or special test
conditions may need to be devised.
This standard does not cover transition joints between cables with extruded insulation and
paper insulated cables.
2 Normative references
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 document (including any amendments) applies.
IEC 60060-1:1989, High-voltage test techniques – Part 1: General definitions and test
requirements
IEC 60183:1984, Guide to the selection of high-voltage cables
IEC 60228:1978, Conductors of insulated cables
IEC 60229:1982, Tests on cable oversheaths which have a special protective function and are
applied by extrusion
IEC 60230:1966, Impulse tests on cables and their accessories
IEC 60332-1:1993, Tests on electric cables under fire conditions – Part 1: Test on a single
vertical insulated wire or cable
IEC 60811-1-1:1993, Common test methods for insulating and sheathing materials of electric
cables – Part 1: Methods for general application – Section 1: Measurement of thickness and
overall dimensions – Tests for determining the mechanical properties
IEC 60811-1-2:1985, Common test methods for insulating and sheathing materials of electric
cables – Part 1: Methods for general application – Section 2: Thermal ageing methods
IEC 60811-1-3:1993, Insulating and sheathing materials of electric cables – Common test
methods – Part 1: General application – Section 3: Methods for determining the density –
Water absorption tests – Shrinkage test

62067 © IEC:2001+A1:2006 – 15 –
– 8 – 62067 © IEC:2001+A1:2006
IEC 60811-1-4:1985, Common test methods for insulating and sheathing materials of electric
cables – Part 1: Methods for general application – Section Four: Tests at low temperature
IEC 60811-2-1:1998, Insulating and sheathing materials of electric and optical cables –
Common test methods – Part 2-1: Methods specific to elastomeric compounds – Ozone
resistance, hot set and mineral oil immersion tests
IEC 60811-3-1:1985, Common test methods for insulating and sheathing materials of electric
cables – Part 3: Methods specific to PVC compounds – Section One: Pressure test at high
temperature – Tests for resistance to cracking
IEC 60811-3-2:1985, Common test methods for insulating and sheathing materials of electric
cables – Part 3: Methods specific to PVC compounds – Section Two: Loss of mass test –
Thermal stability test
IEC 60811-4-1:1985, Common test methods for insulating and sheathing materials of electric
cables – Part 4: Methods specific to polyethylene and polypropylene compounds – Section
One: Resistance to environmental stress cracking – Wrapping test after thermal ageing in air –
Measurement of the melt flow index – Carbon black and/or mineral content measurement in PE
IEC 60840:2004, Power cables with extruded insulation and their accessories for rated
voltages above 30 kV (U = 36 kV) up to 150 kV (U = 170 kV) – Test methods and
m m
requirements.
IEC 60885-3:1988, Electrical test methods for electric cables – Part 3: Test methods for partial
discharge measurements on lengths of extruded power cables
3 Definitions
For the purpose of this International Standard, the following definitions apply.
3.1 Definitions of dimensional values (thicknesses, cross-sections, etc.)
3.1.1
nominal value
value by which a quantity is designated and which is often used in tables
NOTE Usually, in this standard, nominal values give rise to values to be checked by measurements taking into
account specified tolerances.
3.1.2
median value
when several test results have been obtained and ordered in an increasing (or decreasing)
succession, middle value if the number of available values is odd, and mean of the two middle
values if the number is even
3.2 Definitions concerning the tests
3.2.1
routine tests
tests made by the manufacturer on each manufactured component (length of cable or
accessory) to check that the component meets the specified requirements
3.2.2
sample tests
tests made by the manufacturer on samples of complete cable or components taken from a
complete cable or accessory, at a specified frequency, so as to verify that the finished product
meets the specified requirements

62067 © IEC:2001+A1:2006 – 17 –
62067 © IEC:2001+A1:2006 – 9 –
3.2.3
type tests
tests made before supplying on a general commercial basis a type of cable system covered by
this standard, in order to demonstrate satisfactory performance characteristics to meet the
intended application. Once successfully completed, these tests need not be repeated, unless
changes are made in the cable or accessory materials, or design or manufacturing process
which might change the performance characteristics
3.2.4
prequalification test
test made before supplying on a general commercial basis a type of cable system covered by
this standard, in order to demonstrate satisfactory long term performance of the complete
cable system. The prequalification test need only be carried out once unless there is a
substantial change in the cable system with respect to material, manufacturing process, design
and design levels
NOTE A substantial change is defined as that which might adversely affect the performance of the cable system.
The supplier should provide a detailed case, including test evidence, if modifications are introduced, which are
claimed not to constitute a substantial change.
3.2.5
electrical tests after installation
tests made to demonstrate the integrity of the cable system as installed
3.3
cable system
cable with installed accessories
4 Voltage designations and materials
4.1 Rated voltages
In this standard, the symbols U , U and U are used to designate the rated voltages of cables
0 m
and accessories where these symbols have the meanings given in IEC 60183.
4.2 Cable insulating materials
This standard applies to cables insulated with the materials listed in table 1, which also
specifies for cables with each type of insulating compound the maximum operating conductor
temperatures on which the specified test conditions are based.
4.3 Cable oversheathing materials
Tests are specified for four types of oversheath, as follows:
– ST and ST based on PVC;
1 2
– ST and ST based on polyethylene.
3 7
The choice of the type of oversheath will depend on the design of the cable and the mechanical
and thermal constraints during operation.
The maximum conductor temperatures in normal operation given in IEC 60840 apply to this
standard.
62067 © IEC:2001+A1:2006 – 19 –
– 10 – 62067 © IEC:2001+A1:2006
5 Precautions against water penetration in cables
When cable systems are installed in the ground, in easily flooded galleries or in water, a radial
water impermeable barrier around the cable is recommended.
NOTE A test for radial water penetration is not currently available.
Longitudinal water barriers may also be applied, either by agreement between the purchaser
and the manufacturer or as recommended by the manufacturer, to avoid the need to replace
long sections of cable in case of damage in the presence of water.
A test for longitudinal water penetration is given in 12.5.14.
6 Cable characteristics
For the purpose of carrying out and recording the tests described in this standard, the cable
shall be identified. The following characteristics shall be known or declared.

6.1 Rated voltage: values shall be given for U , U, U (see 4.1 and 8.5).
0 m
6.2 Type of conductor, its material and nominal cross-sectional area, in square millimetres.
Presence, if any, and nature of measures taken to achieve longitudinal watertightness. If the
nominal cross-sectional area is not in accordance with IEC 60228, the d.c. conductor
resistance shall be declared.
6.3 Material and nominal thickness of insulation (see 4.2).
6.4 Type of manufacturing process for insulation system.
6.5 Presence, if any, and nature of watertightness measures in screening area.
6.6 Material and construction of metallic screen, e.g. number and diameter of wires, if any.
Material, construction and nominal thickness of metallic sheath, if any. The d.c. resistance of
the metallic screen shall be declared.
6.7 Material and nominal thickness of oversheath.
6.8 Nominal diameter over conductor (d).
6.9 Nominal diameter over complete cable (D).
6.10 Nominal capacitance between conductor and metallic screen/sheath.
7 Accessory characteristics
For the purpose of carrying out and recording the tests described in this standard, the
accessory shall be identified. The following characteristics shall be known or declared.
7.1 Conductor connectors used within the accessories shall be correctly identified with
respect to
– assembly technique;
– tooling, dies and necessary setting;
– preparation of contact surfaces, if applicable;
– type, reference number and any other identification of the connector.

62067 © IEC:2001+A1:2006 – 21 –
62067 © IEC:2001+A1:2006 – 11 –
7.2 Accessories to be tested shall be correctly identified with respect to
– name of manufacturer;
– type, designation, manufacturing date or date code;
– rated voltage (see 6.1);
– installation instructions (reference and date).
8 Test conditions
8.1 Ambient temperature
Unless otherwise specified in the details for the particular test, tests shall be carried out at an
ambient temperature of (20 ± 15) °C.
8.2 Frequency and waveform of power frequency test voltages
Unless otherwise indicated in this standard, the frequency of the alternating test voltages shall
be in the range 49 Hz to 61 Hz. The waveform shall be substantially sinusoidal. The values
quoted are r.m.s. values.
8.3 Waveform of lightning impulse test voltage
In accordance with IEC 60230, the front time of the standard lightning impulse voltage shall be
between 1 µs and 5 µs. The time to half value shall be 50 µs ± 10 µs as specified in
IEC 60060-1.
8.4 Waveform of switching impulse test voltage
In accordance with IEC 60060-1, the standard switching impulse voltage shall have a time to
peak of 250 µs ± 50 µs and a time to half value of 2 500 µs ± 1 500 µs.
8.5 Relationship of test voltages to rated voltages
Where test voltages are specified in this standard as multiples of the rated voltage U , the
value of U for the determination of the test voltages shall be as specified in table 3.
For cables and accessories of rated voltage not shown in the table, the value of U for
determination of test voltages may be the same as for the nearest rated voltage which is given,
provided that the value of U for the cable and accessory is not higher than the corresponding
m
value in the table. Otherwise, and particularly if the rated voltage is not close to one of the
values in the table, the value of U on which the test voltages are based shall be the rated
value, i.e. U divided by 3 .
The test voltages in this standard are based on the assumption that the cables and accessories
are used on systems of category A, as defined in IEC 60183.

62067 © IEC:2001+A1:2006 – 23 –
– 12 – 62067 © IEC:2001+A1:2006
9 Routine tests on cables and on the main insulation
of prefabricated accessories
9.1 General
The following tests shall be carried out on each manufactured length of cable and on the main
insulation of each prefabricated accessory, to check that the whole of each cable length and
that the main insulation of each prefabricated accessory complies with the requirements.
The order in which these tests are carried out is at the discretion of the manufacturer.
a) Partial discharge test (see 9.2).
b) Voltage test (see 9.3).
c) Electrical test on oversheath of the cable, if required (see 9.4).
The applicability of the test on the oversheath of the cable, in item c) above, when the test is
specified in the particular contract or order, depends upon the function of the oversheath in the
installation (see IEC 60229). Therefore, this test shall only be carried out when required for the
particular contract.
The main insulation of prefabricated accessories is required to undergo partial discharge and
voltage routine tests according to alternative 1), 2) or 3) below:
1) on the main insulation of prefabricated accessories installed on cable;
2) by using a host accessory into which a component of an accessory is substituted for test;
3) by using a simulated accessory rig in which the electrical stress environment of a main
insulation component is reproduced.
In cases 2) and 3), the test voltage shall be selected to obtain stresses at least the same as
those on the component in a complete accessory when subjected to the test voltages specified
in 9.2 and 9.3.
NOTE The main insulation of prefabricated accessories consists of the components that come in direct contact
with the cable insulation and are necessary and essential to control the electrical field distribution in the accessory.
Examples are premoulded or precast elastomer or filled epoxy resin insulating components that may be used singly
or jointly to provide the necessary insulation or screening of accessories.
9.2 Partial discharge test
The partial discharge test shall be carried out in accordance with IEC 60885-3 for cables,
except that the sensitivity as defined in IEC 60885-3 shall be 10 pC or better. Testing of
accessories follow the same principles.
The test voltage shall be raised gradually to and held at 1,75 U for 10 s and then slowly
reduced to 1,5 U (see table 3, column 5).
There shall be no detectable discharge from the test object at 1,5 U .
9.3 Voltage test
The voltage test shall be made at ambient temperature using an alternating test voltage at
power frequency.
The test voltage shall be raised gradually to the specified value which shall then be held for the
specified time between the conductor and metallic screen/sheath according to table 3,
column 4.
No breakdown of the insulation shall occur.

62067 © IEC:2001+A1:2006 – 25 –
62067 © IEC:2001+A1:2006 – 13 –
9.4 Electrical test on oversheath of the cable
If required for the particular contract or order, the oversheath shall be subjected to the routine
electrical test specified in clause 3 of IEC 60229.
10 Sample tests on cables
10.1 General
The following tests shall be carried out on samples which, for the tests in items b) and g), may
be complete drum lengths of cable, taken to represent batches:
a) conductor examination (see 10.4);
b) measurement of electrical resistance of conductor (see 10.5);
c) measurement of thickness of insulation and oversheath (see 10.6);
d) measurement of thickness of metallic sheath (see 10.7);
e) measurement of diameters, if required (see 10.8);
f) hot set test for XLPE and EPR insulations (see 10.9);
g) measurement of capacitance (see 10.10);
h) measurement of density of HDPE insulation (see 10.11);
i) lightning impulse voltage test followed by a power frequency voltage test (see 10.12);
j) water penetration test, if applicable (see 12.5.14).
10.2 Frequency of tests
The sample tests in items a) to h) in 10.1 shall be carried out on one length from each batch of
the same type and cross-section of cable, but shall be limited to not more than 10 % of the
number of lengths in any contract, rounded to the nearest whole number.
The frequency of the tests in items i) and j) in 10.1 shall be according to agreed quality control
procedures. In the absence of such an agreement, tests shall be made on the following basis:
Size of order
Number of samples
(core length)
>4 km and ≤20 km 1
>20 km 2
10.3 Repetition of tests
If the sample from any length selected for the tests fails in any of the tests in clause 10, further
samples shall be taken from two further lengths of the same batch and subjected to the same
tests as those in which the original sample failed. If both additional samples pass the tests, the
other cables in the batch from which they were taken shall be regarded as having complied
with the requirements of this standard. If either fail, this batch of cables shall be regarded as
having failed to comply.
10.4 Conductor examination
Compliance with the requirements of IEC 60228 for conductor construction shall be checked by
inspection and measurement when practicable.

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10.5 Measurement of electrical resistance of conductor
The complete cable length, or a sample thereof, shall be placed in the test room, which shall
be maintained at a reasonably constant temperature for at least 12 h before the test. If there is
a doubt that the conductor temperature is not the same as the room temperature, the
resistance shall be measured after the cable has been in the test room for at least 24 h.
Alternatively, the resistance may be measured on a sample of conductor, conditioned for at
least 1 h in a temperature-controlled liquid bath.
The d.c. resistance of the conductor shall be corrected to a temperature of 20 °C and a length
of 1 km in accordance with the formulae and factors given in IEC 60228.
The d.c. resistance of the conductor at 20 °C shall not exceed the appropriate maximum value
specified in IEC 60228 if applicable.
10.6 Measurement of thickness of insulation and cable oversheath
10.6.1 General
The test method shall be in accordance with clause 8 of IEC 60811-1-1.
Each cable length selected for the test shall be represented by a piece taken from one end
after having discarded, if necessary, any portion that may have suffered damage.
10.6.2 Requirements for the insulation
The lowest measured thickness shall not fall below 90 % of the nominal thickness:
t ≥ 0,90 t
min n
and additionally:
tt−
max min
≤ 0,10
t
max
where
t is the maximum thickness, in millimetres;
max
t is the minimum thickness, in millimetres;
min
t is the nominal thickness, in millimetres.
n
NOTE t and t are measured at the same cross-section of the insulation.
max min
The thickness of the semi-conducting screens on the conductor and over the insulation shall
not be included in the thickness of the insulation.
10.6.3 Requirements for the cable oversheath
The lowest measured thickness shall not fall below the nominal thickness by more than
0,1 mm + 15 % of the nominal thickness:
t ≥ 0,85t – 0,1
min n
where
t is the minimum thickness, in millimetres;
min
t is the nominal thickness, in millimetres.
n
In addition, for oversheaths applied onto a substantially smooth surface, the average of the
measured values rounded to 0,1 mm in accordance with annex A shall be not less than the
nominal thickness.
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The latter requirement does not apply to oversheaths applied onto an irregular surface, such as
one formed by metallic screens of wires and/or tapes or corrugated metallic sheaths.
10.7 Measurement of thickness of metallic sheath
The following tests apply if the cable has a metallic sheath of lead, lead alloy or aluminium.
10.7.1 Lead or lead alloy sheath
If the cable has a lead or lead alloy sheath, the minimum thickness of the metallic sheath shall
not fall below the nominal thickness by more than 0,1 mm + 5 % of the nominal thickness, i.e.
t ≥ 0,95t – 0,1
min n
The thickness of the lead sheath shall be measured by one of the following methods, at the
discretion of the manufacturer.
10.7.1.1 Strip method
The measurement shall be made with a micrometer with plane faces of 4 mm to 8 mm
diameter and an accuracy of ±0,01 mm.
The measurement shall be made on a test piece of lead sheath about 50 mm in length
removed from the complete cable. The piece shall be slit longitudinally and carefully flattened.
After cleaning the test piece, a sufficient number of measurements shall be made along the
circumference of the lead sheath and not less than 10 mm away from the edge of the flattened
piece to ensure that the minimum thickness is measured.
10.7.1.2 Ring method
The measurements shall be made with a micrometer having either one flat nose and one ball
nose, or one flat nose and a flat rectangular nose 0,8 mm wide and 2,4 mm long. The ball nose
or the flat rectangular nose shall be applied to the inside of the ring. The accuracy of the
micrometer shall be ±0,01 mm.
The measurements shall be made on a ring of the lead sheath carefully cut from the sample.
The thickness shall be determined at a sufficient number of points around the circumference of
the ring to ensure that the minimum thickness is measured.
10.7.2 Plain or corrugated aluminium sheath
The measurements shall be made with a micrometer having ball noses of radii about 3 mm.
The accuracy shall be ±0,01 mm.
If the cable has an aluminium sheath, the minimum thickness of the metallic sheath shall not
fall below the nominal thickness by more than 0,1 mm + 10 % of the nominal thickness for plain
aluminium sheath, i.e.
t ≥ 0,9t – 0,1
min n
and by more than 0,1 mm + 15 % of the nominal thickness for corrugated aluminium sheath, i.e.
t ≥ 0,85t – 0,1
min n
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The measu
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