EN 61284:1997

Overhead lines - Requirements and tests for fittings

Applies to fittings for overhead lines of nominal voltage above 45 kV. It may also be applied to fittings for overhead lines of lower nominal voltage and to similar fittings for substations.

Freileitungen - Anforderungen und Prüfungen für Armaturen

Lignes aériennes - Exigences et essais pour le matériel d'équipement

S'applique au matériel d'équipement pour lignes aériennes dont la tension nominale dépasse 45 kV. Il est possible de l'appliquer également aux matériels d'équipement pour lignes aériennes dont la tension nominale est inférieure et à un matériel d'équipement similaire pour les postes.

Nadzemni vodi - Zahteve in preskusi za obesno opremo (IEC 61284:1997)

General Information

• Status: Published
• Publication Date: 20-Nov-1997
• Withdrawal Date: 30-Jun-1998
• ICS: 29.240.20 - Power transmission and distribution lines
• Technical Committee: CLC/TC 11 - Overhead electrical lines exceeding 1 kV a.c. (1,5 kV d.c.)
• Drafting Committee: IEC/TC 11 - IEC_TC_11
• Parallel Committee: IEC/TC 11 - IEC_TC_11
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 21-Nov-1997
• Completion Date: 21-Nov-1997
• Ref Project: SIST EN 61284:1999 - Overhead lines - Requirements and tests for fittings

Standards Content (Sample)

SLOVENSKI STANDARD
01-november-1999
Nadzemni vodi - Zahteve in preskusi za obesno opremo (IEC 61284:1997)
Overhead lines - Requirements and tests for fittings
Freileitungen - Anforderungen und Prüfungen für Armaturen
Lignes aériennes - Exigences et essais pour le matériel d'équipement
Ta slovenski standard je istoveten z: EN 61284:1997
ICS:
29.240.20 Daljnovodi Power transmission and
distribution lines
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

NORME
CEI
INTERNATIONALE
IEC
INTERNATIONAL
Deuxième édition
STANDARD
Second edition
1997-09
Lignes aériennes –
Exigences et essais pour le matériel
d’équipement
Overhead lines –
Requirements and tests for fittings
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For price, see current catalogue

61284 © IEC:1997 – 3 –
CONTENTS
Page
FOREWORD . 9
Clause
1 Scope . 11
2 Normative references. 11
3 Definitions. 13
4 Requirements . 17
4.1 General requirements.17
4.1.1 Design. 17
4.1.2 Materials . 17
4.1.3 Dimensions and tolerances . 19
4.1.4 Protection against corrosion . 19
4.1.5 Marking . 19
4.1.6 Instructions for assembly . 21
4.2 Requirements for specific fittings. 21
4.2.1 Insulator set fittings and earth wire fittings. 21
4.2.2 Suspension clamps. 23
4.2.3 Fittings for jointing, terminating and repairing conductor and earth wire . 25
4.2.4 Insulator protective fittings . 25
5 Quality assurance. 27
6 Classification of tests – type tests, sample tests, routine tests . 27
6.1 Type tests . 27
6.1.1 General . 27
6.1.2 Application . 27
6.2 Sample tests. 27
6.2.1 General . 27
6.2.2 Application . 31
6.2.3 Sampling and acceptance criteria. 31
6.3 Routine tests. 31
6.3.1 General . 31
6.3.2 Application and acceptance criteria . 31
7 Visual examination . 31
8 Dimensional and material verification. 33
9 Hot dip galvanizing . 33
10 Non-destructive testing. 35
11 Mechanical tests. 35
11.1 Number of fittings to be tested . 35
11.2 Test piece and attachments for mechanical damage and failure load tests,
conductors used in the mechanical tests. 35

61284 © IEC:1997 – 5 –
Articles Page
11.3 Insulator set fittings and earth wire fittings. 35
11.3.1 Mechanical damage and failure load test. 37
11.3.2 Mechanical damage and failure load test of the attachment point used
during erection. 37
11.4 Suspension clamps. 37
11.4.1 Vertical damage load and failure load test . 37
11.4.2 Slip test on standard clamps with a specified minimum and maximum
slip load . 39
11.4.3 Slip test on standard clamps with only specified minimum slip load. 41
11.4.4 Slip test on controlled slippage clamps . 41
11.4.5 Clamp bolt tightening test. 43
11.5 Tension clamps, dead-end tension joints and mid-span tension joints. 45
11.5.1 Tensile test. 45
11.5.2 Mechanical damage and failure load test. 47
11.5.3 Mechanical damage and failure load test of the attachment point used
during erection. 47
11.5.4 Clamp bolt tightening test. 47
11.6 Partial tension fittings . 47
11.6.1 Partial tension fittings other than T connectors . 49
11.6.2 T connectors . 49
11.7 Repair sleeves . 49
11.8 Insulator protective fittings .51
12 Magnetic losses test. 51
12.1 General . 51
12.2 Test procedure. 51
13 Heat cycle tests . 71
13.1 Purpose. 71
13.2 Joints. 71
13.2.1 General. 71
13.2.2 Service temperatures . 71
13.2.3 Classification for test purposes . 71
13.3 Test specimens. 73
13.3.1 General. 73
13.3.2 Multi-range connectors. 73
13.3.3 Preparation. 73
13.3.4 Data on test specimens. 73
13.4 Test arrangements.73
13.4.1 Test conditions . 73
13.4.2 Reference conductor. 75
13.4.3 Potential points. 75
13.4.4 Installation of test loop. 75
13.4.5 Measurements . 75

61284 © IEC:1997 – 7 –
Articles Page
13.5 Heat cycle test procedure . 77
13.5.1 General. 77
13.5.2 Joints of class A . 79
13.5.3 Joints of class B . 81
14 Corona and radio interference voltage (RIV) tests. 83
14.1 Purpose. 83
14.2 Description of test methods . 83
14.3 General . 85
14.4 Test circuit and instruments. 87
14.5 Corona and RIV test procedures. 87
14.6 Acceptance criteria. 89
14.7 Test report. 89
14.8 Voltage method. 89
14.8.1 Adjacent conductors in a three-phase system . 89
14.8.2 Test set-up and dimensions. 91
14.8.3 Critical variant. 99
14.8.4 Distance from wall (reflection plane) w . 99
14.8.5 Minimum clearance from adjacent live components. 99
14.8.6 Metallic wall . 101
14.9 Voltage gradient method. 101
14.9.1 Conductor voltage on three-phase system. 101
14.9.2 Test set-up and dimensions. 101
14.9.3 Test method . 101
Annexes
A Typical joint types . 105
B Typical test circuit – Class A joints . 107
C Typical test circuit – Class B joints . 109
D Diagrammatic representation of heat cycle test sequence. 111
E Mathematical acceptance criterion . 113
F Examples of normative documents recommended for fitting materials . 117
G Potential points . 121
H Test voltage calibration device . 123
I Example of sampling with inspection by attributes . 129
J Example of sampling with inspection by variables. 131

61284 © IEC:1997 – 9 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
––––––––––
OVERHEAD LINES –
REQUIREMENTS AND TESTS FOR FITTINGS
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, the IEC publishes International Standards. Their preparation is
entrusted to technical committees; any IEC National Committee interested in the subject dealt with may
participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. The IEC collaborates closely with the International Organization
for Standardization (ISO) in accordance with conditions determined by agreement between the two
organizations.
2) The formal decisions or agreements of the IEC on technical matters express, as nearly as possible, an
international consensus of opinion on the relevant subjects since each technical committee has representation
from all interested National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical reports or guides and they are accepted by the National Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61284 has been prepared by IEC technical committee 11: Overhead
lines.
This second edition cancels and replaces the first edition published in 1995 and constitutes a
technical revision.
The text of this standard is based on the following documents:
FDIS Report on voting
11/119/FDIS 11/133/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
Annexes A, B, C, D and E form an integral part of this standard.
Annexes F, G, H, I and J are for information only.
The contents of the corrigendum of Septembre 1998 have been included in this copy.

61284 © IEC:1997 – 11 –
OVERHEAD LINES –
REQUIREMENTS AND TESTS FOR FITTINGS
1 Scope
This International Standard applies to fittings for overhead lines of nominal voltage above
45 kV. It may also be applied to fittings for overhead lines of lower nominal voltage and to
similar fittings for substations.
2 Normative references
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this International Standard. At the time of publication of this standard,
the editions indicated were valid. All normative documents are subject to revision, and parties
to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent editions of the normative documents indicated below.
Members of IEC and ISO maintain registers of currently valid International Standards.
IEC 60050(466): 1990, International Electrotechnical Vocabulary (IEV) – Chapter 466:
Overhead lines
IEC 60060-1: 1989, High-voltage test techniques – Part 1: General definitions and test
requirements
IEC 60120: 1984, Dimensions of ball and socket couplings of string insulator units
IEC 60372: 1984, Locking devices for ball and socket couplings of string insulator units –
Dimensions and tests
IEC 60471: 1977, Dimensions of clevis and tongue couplings of string insulator units
IEC 60826: 1991, Loading and strength of overhead transmission lines
IEC 61089: 1991, Round wire concentric lay overhead electrical stranded conductors
CISPR 16-1: 1993, Specification for radio disturbance and immunity measuring apparatus and
methods – Part 1: Radio disturbance and immunity measuring apparatus
CISPR 18-2: 1986, Radio interference characteristics of overhead power lines and high-voltage
equipment – Part 2: Methods of measurement and procedure for determining limits
1)
ISO 1461,  Hot dip galvanized coatings on fabricated ferrous products – Specifications
–––––––––
1)
To be published.
61284 © IEC:1997 – 13 –
ISO 9000-1: 1994, Quality management and quality assurance standards – Part 1: Guidelines
for selection and use
ISO 9001: 1994, Quality systems – Model for quality assurance in design, development,
production, installation and servicing
ISO 9002: 1994, Quality systems – Model for quality assurance in production, installation and
servicing
ISO 9003: 1994, Quality systems – Model for quality assurance in final inspection and test
ISO 9004-1: 1994, Quality management and quality system elements – Part 1: Guidelines
ISO 2859-1: 1989, Sampling procedures for inspection by attributes – Part 1: Sampling plans
indexed by acceptable quality level (AQL) for lot-by-lot inspection
ISO 2859-2: 1985, Sampling procedures for inspection by attributes – Part 2: Sampling plans
indexed by limiting quality (LQ) for isolated lot inspection
ISO 3951: 1989, Sampling procedures and charts for inspection by variables for percent non-
conforming
3 Definitions
For the purpose of this International Standard the following definitions apply. These definitions
are those which do not appear in the International Electrotechnical Vocabulary (IEV) or differ
from those given in the IEV.
3.1 ball and socket coupling: Coupling consisting of a ball, a socket and a locking device.
3.2 bimetallic fitting: Device which is suitable for jointing conductors of different materials.
3.3 characteristic dimension: Dimension of a component of the test circuit or of a fitting
which characterizes its effect on the electric field. In the case of a bundle, this dimension is
approximately the diameter of an enclosing circle; in the case of a corona ring or sphere, it is
its largest dimension, etc.
3.4 clevis and tongue coupling: Coupling consisting of a clevis, a tongue and a clevis pin or
bolt.
3.5 connector: Device for jointing one or more conductors or earth wires. It may be a tension
or non-tension fitting.
3.6 corona discharge: Electric discharge that only partially breaks down the gas insulation
around the fittings under test.
3.7 corona extinction: Voltage or conductor voltage gradient at which corona discharges
cease during a decreasing test voltage sequence.

61284 © IEC:1997 – 15 –
3.8 corona inception: Voltage or conductor voltage gradient at which corona discharges
initiate during an increasing test voltage sequence.
3.9 earth wire fitting: Any component of an assembly for attaching an earth wire to a
supporting structure other than a suspension clamp, a tension fitting or a mechanical protective
fitting.
3.10 factory-formed helical conductor fitting: Fitting consisting of helically formed wires
which provide the force necessary to grip the conductor or earth wire by self-tightening.
3.11 insulator set fitting: Any component of a suspension or tension insulator set other than
a string insulator unit, a suspension clamp, a conductor tension fitting, an insulator protective
fitting or a mechanical protective fitting.
3.12 joint: Connector and that part of the conductor or earth wire that has been brought into
intimate contact with it by compression or other mechanical means.
3.13 mechanical damage load: Maximum load which can be applied to a fitting without an
unacceptable permanent deformation when the fitting is tested under specified test conditions.
NOTE – The unacceptable permanent deformation should be agreed upon between purchaser and supplier.
3.14 mechanical failure load: Maximum load which can be applied to a fitting under
specified test conditions.
3.15 mechanical protective fitting: Any device attached to a conductor or to an earth wire
for their mechanical protection.
3.16 radio-interference voltage (RIV): Voltage in the radio frequency range produced by an
electromagnetic disturbance and which can be measured in accordance with CISPR 16 on the
test circuit equipped with the fitting.
3.17 spacer damper: Device which keeps apart the subconductors of a bundle in a given
geometrical configuration and is able to reduce aeolian vibrations and subspan oscillations of
the subconductors. [IEV 466-11-02, modified]
3.18 specified maximum radio-interference voltage: Maximum acceptable radio-interference
voltage at a specified test voltage or conductor voltage gradient. This is specified by the
purchaser or declared by the supplier.
3.19 specified minimum corona extinction: Minimum acceptable voltage or conductor
voltage gradient at which corona discharges cease. This is specified by the purchaser or
declared by the supplier.
3.20 specified minimum failure load: Minimum load specified by the purchaser or declared
by the supplier at which mechanical failure will not take place.
NOTE – From the probabilistic point of view, the specified minimum failure load corresponds to the value having
the probability of e % in the distribution function of the strength of the fitting. The exclusion limit e % is usually
taken within 2 % to 5 % with 10 % being the upper limit (see IEC 60826).

61284 © IEC:1997 – 17 –
3.21 specified minimum mechanical damage load: Minimum load specified by the
purchaser or declared by the supplier at which unacceptable permanent deformation will not
take place.
3.22 specified minimum slip load: Minimum load specified by the purchaser or declared by
the supplier at which slippage will not take place.
3.23 vibration damper: Device attached to a conductor or an earth wire in order to reduce
aeolian vibrations. [IEV 466-11-16, modified]
4 Requirements
4.1 General requirements
4.1.1 Design
The fittings shall be designed so as to
– avoid damaging the conductor under service conditions;
– withstand the mechanical loads relevant to installation, maintenance and service, the
designed service current, including short-circuit current, the service temperatures and
environmental circumstances;
– ensure that individual components are secured against becoming loose in service;
– have limited corona effects.
Fittings for live line maintenance shall be suitably designed for safe and easy handling.
Surfaces of compression fittings in contact with the conductor or earth wire shall be protected
from becoming contaminated before installation.
Brittleness of finished parts shall be avoided by adopting suitable materials and manufacturing
process.
4.1.2 Materials
Fittings shall be made of any material suitable for the purpose.
4.1.2.1 Metallic materials
The materials shall meet service life requirements and shall not be liable to intergranular or
stress corrosion. They shall not cause corrosion of any other parts of the conductor or earth
wire.
The materials of compression fittings shall be capable of withstanding the cold working due to
compression. Furthermore, the steel compression components shall also have a sufficient
impact strength after the compression.
Examples of suitable materials are the following:
– aluminium or aluminium alloy;
– galvanized steel;
– galvanized malleable or ductile iron;
– stainless steel;
– copper and copper alloys.
61284 © IEC:1997 – 19 –
It is recommended that ISO standards for materials be used where they exist. Examples of ISO
standards for fitting materials are listed in annex F.
4.1.2.2 Non-metallic materials
Non-metallic materials employed shall have good resistance to ageing and be capable of
withstanding service temperatures without detrimental change of properties. Materials shall
have adequate resistance to the effects of ozone, ultra-violet radiation and air pollution over
the whole range of the service temperature.
They shall not induce corrosion in materials which are in contact with them.
4.1.3 Dimensions and tolerances
The dimensions shall be shown on contract drawings.
Particular regard shall be paid to those dimensions which involve interchangeability, correct
assembly, and those for which gauges are specified. Reference shall be made to relevant
standards, for example IEC 60120, IEC 60372, etc.
Tolerances applied to dimensions shall ensure that the fittings meet their specified mechanical
and electrical requirements.
4.1.4
Protection against corrosion
All parts of insulator, conductor and earth wire fittings shall be either inherently resistant to
atmospheric corrosion or be suitably protected against corrosion, such as can occur in
transport, storage and in service. All ferrous parts which will be exposed to the atmosphere in
service, except those made of appropriate stainless steel, shall be protected by hot dip
galvanizing in accordance, for example, with ISO 1461 or other means giving equivalent
protection.
Moreover, unless special measures are taken, there shall never be contact between metals for
which the difference in electrochemical potential can give rise to galvanic corrosion capable of
impairing the efficiency of the whole equipment. This applies especially to those parts of the
fittings that are in direct contact with the conductor.
All external threads shall be cut or rolled before hot dip galvanizing. Internal threads can be cut
before or after hot dip galvanizing. If cut after galvanizing they shall be oiled or greased.
4.1.5 Marking
Marking shall ensure the system of traceability for each of the component parts of the fittings.
When practicable, and unless otherwise agreed between purchaser and manufacturer, fittings
shall be clearly and indelibly marked as follows:

61284 © IEC:1997 – 21 –
Fittings used as individual components
Castings
a) identification of fittings
(reference number/specified minimum failure load);
b) manufacturer’s identification;
c) date of manufacture (month and year);
d) cast code.
Forgings
a) identification of fittings
(reference number/specified minimum failure load);
b) manufacturer’s identification;
c) date of manufacture (month and year).
Links and plates
a) identification of fittings
(reference number/specified minimum failure load);
b) manufacturer’s identification;
c) date of manufacture (month and year).
Assemblies of fittings
a) identification
(reference number/specified minimum failure load);
b) manufacturer’s identification;
c) date of manufacture of individual items (month and year);
d) conductor diameter range or conductor code(s), as agreed between purchaser and
supplier;
e) fitting bolt installation torque (unless breakaway torque bolts are used).
Conductor compression fittings
a) identification
(reference number/specified minimum failure load);
b) manufacturer’s identification;
c) date of manufacture (month and year);
d) conductor size or code name;
e) compression die sizes;
f) length to be compressed.
4.1.6 Instructions for assembly
The manufacturers shall provide the assembly instructions of the fittings as far as necessary.
4.2 Requirements for specific fittings
4.2.1 Insulator set fittings and earth wire fittings
For parts made of forged steel, holes which are under mechanical stress can be made by hot
punching provided that the holes conform to tolerances on at least 70 % of punched thickness.
For parts made of forged steel, holes which are not under mechanical stress can be made by
cold or hot punching without the aforementioned limits.

61284 © IEC:1997 – 23 –
4.2.2 Suspension clamps
The conductor or the earth wire installed in the suspension clamps can be used bare or
equipped with armour rods.
The suspension clamps shall be so designed that the effects of vibration, both on the
conductor or on the earth wire and on the clamps themselves, are minimized. The clamps shall
be designed to avoid localized pressure or damage to the conductor or the earth wire.
The suspension clamps shall have sufficient contact surface to avoid damage by fault currents.
The wear resistance of the articulation assembly shall be sufficient to prevent deterioration in
service.
Magnetic losses shall not exceed the laid down value, if specified.
The body of a suspension clamp shall permit oscillation around a horizontal axis perpendicular
to the conductor.
Typical suspension clamps are
– clamps with articulation above the conductor; the pivot is above the horizontal plane
passing through the conductor axis at the suspension point (see figure 1a);
– clamps with articulation in the plane of the axis of the conductor (twin or triple
articulation) (see figure 1b); one of the three articulations is in the horizontal plane of the
conductor axis;
– clamps with articulation under the axis of the conductor (see figure 1c).
The manufacturer shall provide the purchaser with the usage limits of the suspension clamps.
NOTE – For each type of clamp, the purchaser can choose between
– standard clamps: the slip load of the conductor or earth wire is not lower than a specified minimum slip
load;
– controlled slippage clamps: the slip load of the conductor remains between two values defined by
mutual agreement between the purchaser and the supplier.
Figure 1a               Figure 1b                  Figure 1c
Figure 1 – Typical suspension clamps

61284 © IEC:1997 – 25 –
4.2.3 Fittings for jointing, terminating and repairing conductor and earth wire
Fittings for the purpose of jointing, terminating and repairing conductor and earth wire include,
but are not limited to, the following:
– compression type connectors;
– cone or wedge type clamps;
– bolted type clamps;
– factory-formed helical fittings;
– fittings installed using an explosive charge.
The above fitting types may be used for tension and non-tension joints, and T connectors.
When the fittings are designed so as not to provide electrical continuity of the conductor (e.g. a
tension clamp) the fittings shall not reduce the electrical capability of the conductor or earth
wire.
Fittings used for electrical continuity connections shall meet the requirements of clause 13.
Those fittings with auxiliary eyes intended for use during construction or maintenance shall be
marked with a specified minimum failure load stated by the manufacturer.
All fittings shall be designed to minimize internal voids and to prevent the ingress or
entrapment of moisture during service.
Fittings may be provided with an oxide-inhibiting compound intended to reduce metal oxidation
at metal-to-metal electrical contact points. These compounds are commonly used in
compression fittings to fill internal voids and to prevent ingress of water during service.
Fittings and connectors shall be designed in such away that after installation, the initial contact
area between the fitting and the conductor does not raise stresses which can lead to failure
under aeolian vibration or other conductor oscillation conditions.
Fittings and connectors intended to connect conductors of two dissimilar materials shall be
designed to avoid bimetallic corrosion.
Fittings and connectors shall be designed to avoid localized pressures which may cause
excessive cold flow of the conductor or earth wire material.
Fittings and connectors intended for the restoration of electrical and mechanical properties of a
conductor shall have clearly defined manufacturer's instructions as to the extent of damage
which they are intended to repair.
4.2.4 Insulator protective fittings
Should steel tubes be used for insulator protective fittings, both the internal and external
surfaces of the tubes shall be hot dip galvanized.
When the tube is sealed after galvanizing, the quality of the internal surface shall be agreed
between purchaser and supplier.
For insulator protective fittings designed to protect insulator sets against damage caused by
power arcs (arcing horns, arcing rings, rings), the short-circuit current conditions shall be
stated by the customer in the order.

61284 © IEC:1997 – 27 –
The protective fittings shall be designed in such a way as not to be subject to breakage through
fatigue due to vibration caused by the wind. The insulator protective fittings shall withstand a
static mechanical load agreed upon between supplier and purchaser.
5 Quality assurance
A quality assurance programme taking into account the requirements of this standard can be
used by agreement between the purchaser and the supplier to verify the quality of the fittings
during the manufacturing process.
Detailed information on the use of quality assurance is given in the following ISO standards:
ISO 9000-1, ISO 9001, ISO 9002, ISO 9003, ISO 9004-1.
6 Classification of tests – type tests, sample tests, routine tests
6.1 Type tests
6.1.1 General
Type tests are intended to establish design characteristics. They are normally only made once
and repeated only when the design or the material of the fitting is changed. The results of type
tests are recorded as evidence of compliance with design requirements.
6.1.2 Application
Fittings shall be subject to type tests in accordance with table 1. In addition other tests may be
agreed between purchaser and supplier, for example corrosion tests, ageing tests, fatigue
tests, short-circuit tests and power arc tests.
6.2 Sample tests
6.2.1 General
Sample tests are intended to verify the quality of materials and workmanship.

Table 1 – Tests on fittings
1)
Insulator set fittings and Suspension clamps Tension joints and tension Partial tension fittings Repair sleeve Insulator protective fittings
earth wire fittings clamps
Clause Test Type Sample Routine Type Sample Routine Type Sample Routine Type Sample Routine Type Sample Routine Type Sample Routine
tests tests tests tests tests tests tests tests tests tests tests tests tests tests tests tests tests tests
2) 3) 2) 3) 2) 3) 2) 3) 2) 3) 2) 3)
7 Visual examination X X X XX X XX X XX X XX X XX X
8 Dimensional and
3) 3) 3) 3) 3) 3)
material verification
XX X XX X XX X XX X XX X XX X
9 Hot dip galvanizing
3) 3) 3) 3) 3) 3)
XXX XX XX XX X X
10 Non-destructive 3) 3) 3) 3) 3) 3) 3) 3) 3) 3) 3) 3) 3) 3)
X X X X X X X X X X X X X X
testing
11 Mechanical tests
– damage and
3)4) 3)4) 3) 3) 3) 3)
failure load test X X X XX X XX X X X
– slip test
XX
– clamp bolt
2) 2)
tightening test X X XX
– tensile test XX X X X
– damage and
failure load test of
3) 3) 3)4)
the attachment point XX XX X
used during erection
12 Magnetic losses test
3) 3)
X X
13 Heat cycle tests
5) 5)
X X
14 Corona and RIV test
3)6) 3)6) 3) 3) 3) 3)6)
X X X X X X
1)
Includes electrical gradient devices
2)
Inspection by attributes only
3)
By agreement between purchaser and supplier
4)
Only as regards damage load test
5)
Only for current-carrying joints
6)
Only in connection with the complete insulator set

61284 © IEC:1997 – 31 –
6.2.2 Application
Overhead line fittings shall be subjected to sample tests as listed in table 1. The samples to be
tested shall be selected at random from the lot offered for acceptance. The purchaser has the
right to make the selection.
6.2.3 Sampling and acceptance criteria
Unless otherwise agreed between purchaser and supplier, the sampling plan procedures
according to ISO 2859-1 and ISO 2859-2 (inspection by attributes) and to ISO 3951 (inspection
by variables) shall be applied.
For each sample test, the type of inspection (by attributes or by variables) and the detailed
procedures (inspection level, acceptable quality level, single, double or multiple sampling, etc.)
shall be agreed between purchaser and supplier (see example in annex I for inspection by
attributes, and annex J for inspection by variables).
NOTE – Sampling inspection by variables is an acceptance sampling procedure to be used in place of
inspection by attributes when it is more appropriate to measure on some continuous scale the characteristic(s)
under consideration. In the case of failure load tests and similar expensive tests, better discrimination between
acceptable quality and objective quality is available with acceptance sampling by variables than by attributes for
the same sample size.
The purpose of the sampling process may also be important in the choice between a variables or attributes plan.
For example, a purchaser may choose to use an attributes acceptance sampling plan to ensure that parts in a
shipment lot are within a required dimensional tolerance; the manufacturer may make measurements under a
variables sampling plan of the same dimensions because he is concerned with gradual trends or changes which
may affect his ability to provide shipment lots which meet the AQL.
6.3 Routine tests
6.3.1 General
Routine tests are intended to prove conformance of fittings to specific requirements and are
made on every fitting. The tests shall not damage the fitting.
6.3.2 Application and acceptance criteria
Whole lots of fittings may be subjected to routine tests as listed in table 1. Fittings which do not
conform to the requirements shall be discarded.
7 Visual examination
Type tests shall include visual examination to ascertain conformity of the fittings, in all
essential respects, with the contract drawings. Deviations from the drawings shall be subject to
agreement between supplier and purchaser and shall be appropriately documented as an
agreed concession.
Sample tests include visual examination in accordance with 6.2.3. Visual examination shall
ensure conformity of manufacturing process, shape, coating and surface finish of the fitting
with the contract drawings. Particular attention shall be given to markings required and to the
finish of surfaces which come into contact with the conductor.
NOTE – Verification of marking may include marking required by the purchaser in order to verify inspection or
testing (e.g. hardness tests, indent marks, inspectors’ stamps, etc.).

61284 © IEC:1997 – 33 –
For fittings subject to corona type tests, the sample test shall include a comparison of shape
and surface finish with one of the corona type test samples when agreed between purchaser
and supplier.
Routine tests do not include visual examination unless otherwise agreed between supplier and
purchaser or unless included in the quality assurance system of the supplier.
8 Dimensional and material verification
Type and sample tests shall include verification of dimensions, in accordance with clause 6, to
ensure that fittings are within the dimensional tolerances stated on contract drawings. The
purchaser may choose to witness the measurement of selected dimensions or may inspect the
supplier's documentation when this is available. Measuring devices/gauges shall be selected
with regard to the required precision and accuracy. Documentary evidence of calibration of
such devices shall be provided on request.
Routine tests shall include a specified level of dimensional checking when required by the
contract quality plan.
NOTE – Particular attention should be given to those dimensions potentially affecting fitting interchangeability
(for example ball and socket couplings (IEC 60120); clevis and
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