IEC 60433:2021

Insulators for overhead lines with a nominal voltage above 1000 V - Ceramic insulators for AC systems - Characteristics of insulator units of the long rod type

IEC 60433:2021 is applicable to string insulator units of the long rod type with insulating parts of ceramic material intended for use in AC overhead power lines with a nominal voltage greater than 1000 V and a frequency not greater than 100 Hz. It is also applicable to insulators of similar design, used in substations. This document is applicable to ceramic string insulator units of the long rod type, either with a clevis end fitting at both ends for coupling with a tongue, or with a socket end fitting at both ends for coupling with a pin ball. The object of this document is to prescribe specified values for electrical and mechanical characteristics, and for the principal dimensions of ceramic string insulator units of the long rod type. This fourth edition cancels and replaces the third edition published in 1998. This edition includes the following significant technical changes with respect to the previous edition:
- wording in Scope changed from "should" to "are intended to";
- new normative references added;
- title of Clause 4 amended, new Note 4 added;
- Table 1 expanded to include more specified mechanical failing loads.

Isolateurs pour lignes aériennes de tension nominale supérieure à 1 000 V - Isolateurs en céramique pour réseaux à tension alternative - Caractéristiques des éléments d'isolateurs du type à long fût

L'IEC 60433:2021 s'applique aux éléments de chaînes d'isolateurs du type à long fût ayant des parties isolantes en matière céramique destinés aux lignes aériennes fonctionnant en courant alternatif à une tension nominale supérieure à 1 000 V et à une fréquence au plus égale à 100 Hz. Elle s'applique également aux isolateurs du même type utilisés dans les postes. Le présent document s'applique aux éléments de chaînes d’isolateurs en céramique du type à long fût ayant à chaque extrémité soit une chape destinée à recevoir un tenon, soit un logement de rotule pour assemblage avec une tige à rotule. Le présent document a pour objet de prescrire des valeurs spécifiées pour les caractéristiques électriques et mécaniques et pour les principales dimensions des éléments de chaînes d'isolateurs en céramique du type à long fût. Cette quatrième édition annule et remplace la troisième édition parue en 1998. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
- reformulation du domaine d'application: "il convient d’utiliser les caractéristiques mécaniques ainsi que les longueurs L (voir Article 4) de la présente norme " remplacé par "les caractéristiques mécaniques ainsi que les longueurs L (voir Article 4) de la présente norme sont prévues pour être utilisées";
- ajout de nouvelles références normatives;
- modification du titre de l'Article 4, ajout d'une nouvelle Note 4;
- Le Tableau 1 a été étoffé pour intégrer un plus grand nombre de charges de rupture mécanique spécifiées.

General Information

• Status: Published
• Publication Date: 11-Jan-2021
• ICS: 29.080.10 - Insulators
• ICS: 29.240.20 - Power transmission and distribution lines
• Technical Committee: TC 36 - Insulators
• Drafting Committee: MT 17 - TC 36/MT 17
• Current Stage: PPUB - Publication issued
• Start Date: 12-Jan-2021
• Completion Date: 20-Jan-2021

Relations

• Revises: IEC 60433:1998 - Insulators for overhead lines with a nominal voltage above 1 000 V - Ceramic insulators for a.c. systems - Characteristics of insulator units of the long rod type
• Effective Date: 05-Sep-2023

Overview

IEC 60433:2021 - Insulators for overhead lines with a nominal voltage above 1000 V - Ceramic insulators for AC systems - Characteristics of insulator units of the long rod type - defines the electrical, mechanical and dimensional characteristics of ceramic long‑rod string insulator units used on AC overhead power lines (nominal voltage > 1 000 V, frequency ≤ 100 Hz). The standard applies to long‑rod units with either ball-and-socket or clevis-and-tongue end fittings and prescribes specified values (e.g., lightning impulse withstand, wet power‑frequency withstand, tensile mechanical failing load, maximum length/diameter and minimum creepage distance). IEC 60433:2021 is the fourth edition and updates the third edition (1998), including added normative references and expanded mechanical failing load values.

Key topics and requirements

• Scope & applicability: Ceramic long‑rod insulators for overhead lines and similar substation use; designed for lightly polluted areas (creepage bases given).
• Electrical characteristics: Specified dry lightning impulse withstand voltages and wet power‑frequency withstand voltages (aligned with IEC 60071‑1).
• Mechanical characteristics: Specified tensile mechanical failing loads (designations such as L160 indicate 160 kN); Table 1 lists standardised failing loads and related dimensions.
• Creepage distance: Minimum nominal creepage distances based on a unified specific creepage (reference values 16 mm/kV and 27.8 mm/kV are cited per IEC TS 60815 guidance); shorter or longer creepage distances can be used when justified by site conditions.
• Dimensions & couplings: Maximum nominal length L, maximum nominal diameter D and standard coupling sizes are defined; clevis/tongue couplings referenced to IEC 60471 and ball/socket to IEC 60120.
• Designation & marking: Unit marking rules (manufacturer, year, and designation like L160B550) to ensure traceability and interchangeability.
• Limits: The document does not include test procedures or end‑fitting dimensions; normative references provide those details.

Practical applications and users

Who uses IEC 60433:2021:

• Insulator manufacturers for product design and specification
• Transmission/distribution utilities and system designers for component selection
• Substation designers and contractors specifying ceramic long‑rod insulators
• Procurement teams for compliant sourcing and acceptance criteria
• Testing and certification bodies verifying conformance

Practical benefits:

• Ensures interoperability and consistent performance across suppliers
• Guides selection based on mechanical load, voltage withstand and pollution severity
• Supports reliable overhead line design and life‑cycle planning

Related standards

• IEC 60071‑1 (Insulation co‑ordination)
• IEC 60120 (Ball and socket dimensions)
• IEC 60471 (Clevis and tongue dimensions)
• IEC 60383‑1 (Insulator definitions, tests)
• IEC 60672‑1 / IEC 60672‑3 (Ceramic insulating materials)
• IEC TS 60815 (Selection for polluted conditions)

Keywords: IEC 60433:2021, long rod insulators, ceramic insulators, overhead lines, creepage distance, lightning impulse withstand voltage, mechanical failing load, ball and socket, clevis and tongue, AC systems.

Standards Content (Sample)

IEC 60433 ®
Edition 4.0 2021-01
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Insulators for overhead lines with a nominal voltage above 1 000 V – Ceramic
insulators for AC systems – Characteristics of insulator units of the long rod
type
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IEC 60433 ®
Edition 4.0 2021-01
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Insulators for overhead lines with a nominal voltage above 1 000 V – Ceramic

insulators for AC systems – Characteristics of insulator units of the long rod

type
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.080.10; 29.240.20 ISBN 978-2-8322-9280-8

– 2 – IEC 60433:2021 RLV © IEC 2021
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Characteristics, dimensions and type of long rod insulators . 6
5 Designation and marking . 7
Bibliography . 11

Figure 1 – Long rod insulator with clevis couplings, type C . 10
Figure 2 – Long rod insulator with socket couplings, type B . 10

Table 1 – Specified values for long rod insulators . 8

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INSULATORS FOR OVERHEAD LINES
WITH A NOMINAL VOLTAGE ABOVE 1 000 V –
CERAMIC INSULATORS FOR AC SYSTEMS –
CHARACTERISTICS OF INSULATOR UNITS OF THE LONG ROD TYPE

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
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). 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. 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 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 IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
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.

This redline version of the official IEC Standard allows the user to identify the changes
made to the previous edition IEC 60433:1998. A vertical bar appears in the margin
wherever a change has been made. Additions are in green text, deletions are in
strikethrough red text.
– 4 – IEC 60433:2021 RLV © IEC 2021
International Standard IEC 60433 has been prepared by IEC technical committee 36:
Insulators.
This fourth edition cancels and replaces the third edition published in 1998. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) wording in Scope changed from "should" to "are intended to";
b) new normative references added;
c) title of Clause 4 amended, new Note 4 added;
d) Table 1 expanded to include more specified mechanical failing loads.
The text of this International Standard is based on the following documents:
FDIS Report on voting
36/498/FDIS 36/500/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.
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.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
INSULATORS FOR OVERHEAD LINES
WITH A NOMINAL VOLTAGE ABOVE 1 000 V –
CERAMIC INSULATORS FOR AC SYSTEMS –
CHARACTERISTICS OF INSULATOR UNITS OF THE LONG ROD TYPE

1 Scope
This International Standard is applicable to string insulator units of the long rod type with
insulating parts of ceramic material intended for use in AC overhead power lines with a
nominal voltage greater than 1 000 V and a frequency not greater than 100 Hz. It is also
applicable to insulators of similar design, used in substations.
This document is applicable to ceramic string insulator units of the long rod type, either with a
clevis end fitting at both ends for coupling with a tongue, or with a socket end fitting at both
ends for coupling with a pin ball.
The object of this document is to prescribe specified values for electrical and mechanical
characteristics, and for the principal dimensions of ceramic string insulator units of the long
rod type.
This document is applicable to string insulator units for use on overhead lines situated in
lightly polluted areas, and the creepage distances given in Table 1 have been established
accordingly, using the IEC TS 60815-2 recommendation of 16 mm/kV for pollution level I 27,8
mm/kV for SPS class. However, shorter creepage distances may be used are applicable for
use in some non-polluted areas. If specific operating conditions require or allow non-standard
(longer or shorter) creepage distances, the mechanical characteristics as well as the lengths
L (see Clause 4) of this document should are intended to be used unless the need for
exceptionally long creepage distances requires values of L greater than those given in Table
1. In the case of special requirements, e.g. very heavy polluted areas and for other particular
or extreme environmental conditions, it may be necessary for certain dimensions to be
changed.
NOTE As far as reasonably applicable, this document may is also applicable to be applied to
similar insulator units outside the scope of this standard, such as insulators for electric
traction lines. This document does not include tests on insulators and dimensions of end
fittings.
NOTE Ball and socket couplings are covered by IEC 60120, clevis and tongue couplings by
IEC 60471.
NOTE 1 For the definition of site pollution levels severity, see applicable part of IEC TS 60815.
NOTE 2 The term "ceramic" is used in this document to refer to porcelain materials and, contrary to North
American practice, does not include glasses.
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 60071-1:1993, Insulation co-ordination – Part 1: Definitions, principles and rules
IEC 60120:1984, Dimensions of ball and socket couplings of string insulator units

– 6 – IEC 60433:2021 RLV © IEC 2021
IEC 60383-1:1993, Insulators for overhead lines with a nominal voltage above 1 000 V – Part
1: Ceramic or glass insulator units for AC systems – Definitions, test methods and acceptance
criteria
IEC 60471:1977, Dimensions of clevis and tongue couplings of string insulator units
IEC 60672-1:1995, Ceramic and glass insulating materials – Part 1: Definitions and
classification
IEC 60672-3:1997, Ceramic and glass insulating materials – Part 3: Specification for
individual materials
IEC 60815:1986 Guide for the selection of insulators in respect of polluted conditions
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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
long rod insulator
suspension or tension insulator consisting of an approximately cylindrical insulating part
provided with sheds and equipped at the ends with external metal fittings
Note 1 to entry: The insulator is designed in such a manner that the shortest puncture path through solid
insulating material is at least equal to half the arcing distance. Therefore it is a class A insulator according to
IEC 60383-1.
4 Characteristics, dimensions and type of long rod insulators
String insulator units of the long rod type are characterised by the following specified
characteristics:
– the standard lightning impulse withstand voltage (see IEC 60071-1);
– the wet power frequency withstand voltage (see IEC 60071-1);
– the tensile mechanical failing load;
– the maximum nominal length L of the insulator;
– the maximum nominal diameter D of the insulating part;
– the minimum nominal creepage distance;
– the standard coupling.
The corresponding values are specified in Table 1. The minimum nominal creepage distances
are based on a unified specific creepage distance of 16 27,8 mm/kV for the lowest value of
the highest voltage for equipment corresponding to the specified value of the standard
lightning impulse withstand (in accordance with IEC 60071-1).
NOTE 1 The tolerances given in IEC 60383-1 are applicable to all the dimensions in Table 1, even if the
adjectives "minimum" or "maximum" are used before the term "nominal".
NOTE 2 Dry lightning impulse withstand voltage and wet power frequency withstand voltage are specified in
Table 1 for single unit string insulators. Values of withstand voltages of insulator strings consisting of more than
one unit are not contained in this document.

NOTE 3 The rod diameter is not specified since it depends on the mechanical characteristics of the insulating
material. Information on the definition and classification of ceramic insulating materials can be found in
IEC 60672-1 and IEC 60672-3.
NOTE 4 Examples of shed profile are given in Clause 8, “Choice of profile” of IEC TS 60815-2:2008.
5 Designation and marking
Long rod insulators are designated in Table 1 by the letter L, followed by a figure indicating
the specified mechanical failing load in kilonewtons. Then follows the letter B or C indicating
ball and socket or clevis and tongue coupling respectively, followed by the value of the
lightning impulse withstand voltage in kilovolts.
EXAMPLE:
L 160 B 550 indicates:
L: long rod insulator;
160: specified mechanical failing load, tension, 160 kN;
B: ball and socket coupling;
550: dry lightning impulse withstand voltage 550 kV.
The insulators shall be marked either on the upper shed or on the metal parts with the name
or trade mark of the manufacturer and the year of manufacture. In addition, each unit shall be
marked with the specified mechanical failing load, by using the first part of the designation; for
instance, the insulator shall be marked L 160 for the units with 160 kN specified mechanical
failing load.
These markings shall be legible and indelible.
Figure 1 shows a long rod insulator with clevis couplings. Figure 2 shows a long rod insulator
with socket couplings.
– 8 – IEC 60433:2021 RLV © IEC 2021

Table 1 – Specified values for long rod insulators
Coupling B Coupling C
Designation Standard Wet power Specified Maximum Minimum Maximum Standard Maximum Standard coupling size
lightning frequency mechanical nominal nominal creepage nominal coupling size nominal (coupling pin diameter,
impulse withstand failing load diameter D on distance length L (pin diameter, length L see IEC 60471 –
withstand voltage the insulating (16 27.8 mm/kV, see IEC 60120) non-preferred
voltage part see Clause 4) sizes in brackets)
kV kV kN mm mm mm mm
L 40 B/C 170 170 70 40 160 576 380 11 400 13L
L 60 B/C 170 170 70 60 160 576 400 11 420 13L
L 100 B/C 170 170 70 100 180 576 450 16 475 19L (16L)
L 100 B/C 250 250 95 100 180 832 580 16 605 19L (16L)
L 100 B/C 325 325 140 100 180 1 160 870 16 900 19L (16 L)
L 100 B/C 450 450 185 100 180 1 968 1 085 16 1 120 19L (16L)
L 100 B/C 550 550 230 100 180 1 968 1 240 16 1 270 19L (16L)
L 120 B/C 325 325 140 120 200 1 160 870 16 905 19L (16L)
L 120 B/C 450 450 185 120 200 1 968 1 085 16 1 120 19L (16L)
L 120 B/C 550 550 230 120 200 1 968 1 240 16 1 275 19L (16L)
L 120 B/C 650 650 275 120 200 2 320 1 430 16 1 465 19L (16L)
L 160 B/C 325 325 140 160 210 1 160 885 20 920 19L
L 160 B/C 450 450 185 160 210 1 968 1 100 20 1 135 19L
L 160 B/C 550 550 230 160 210 1 968 1 255 20 1 290 19L
L 160 B/C 650 650 275 160 210 2 320 1 445 20 1 465 19L
L 210 B/C 325 325 140 210 220 1 160 905 20 940 22L
L 210 B/C 450 450 185 210 220 1 968 1 120 20 1 155 22L
L 210 B/C 550 550 230 210 220 1 968 1 275 20 1 310 22L
L 210 B/C 650 650 275 210 220 2 320 1 465 20 1 500 22L

Coupling B Coupling C
Designation Standard Wet power Specified Maximum Minimum Maximum Standard Maximum Standard coupling size
lightning frequency mechanical nominal nominal creepage nominal coupling size nominal (coupling pin diameter,
impulse withstand failing load diameter D on distance length L (pin diameter, length L see IEC 60471 –
withstand voltage the insulating (16 27.8 mm/kV, see IEC 60120) non-preferred
voltage part see Clause 4) sizes in brackets)
kV kV kN mm mm mm mm
L 250 B/C 550 550 230 250 230 1 968 1 305 24 1 335 22L
L 250 B/C 650 650 275 250 230 2 320 1 500 24 1 530 22L
L 300 B/C 550 550 230 300 240 1 968 1 330 24 1 365 25L
L 300 B/C 650 650 275 300 240 2 320 1 520 24 1 560 25L
L 330 B/C 550 550 230 330 250 1 968 1 360 28 1 400 28L
L 330 B/C 650 650 275 330 250 2 320 1 550 28 1 595 28L
L 360 B/C 550 550 230 360 250 1 968 1 360 28 1 410 28L
L 360 B/C 650 650 275 360 250 2 320 1 550 28 1 600 28L
L 400 B/C 550 550 230 400 260 1 968 1 400 28 1 460 28L
L 400 B/C 650 650 275 400 260 2 320 1 600 28 1 660 28L
L 420 B/C 550 550 230 420 260 1 968 1 400 28 1 460 28L
L 420 B/C 650 650 275 420 260 2 320 1 600 28 1 660 28L
L 530 B/C 550 550 230 530 270 1 968 1 450 32 1 520 32L
L 530 B/C 650 650 275 530 270 2 320 1 650 32 1 720 32L
L 550 B/C 550 550 230 550 270 1 986 1 450 32 1 520 32L
L 550 B/C 650 650 275 550 270 2 320 1 650 32 1 720 32L

– 10 – IEC 60433:2021 RLV © IEC 2021

Figure 1 – Long rod insulator with clevis couplings, type C

Figure 2 – Long rod insulator with socket couplings, type B

Bibliography
[1] IEC 60050-471, International Electrotechnical Vocabulary (IEV) – Part 471: Insulators
[2] IEC 60071-1, Insulation co-ordination – Part 1: Definitions, principles and rules
[3] IEC 60120, Ball and socket couplings of string insulator units – Dimensions
[4] IEC 60471, Clevis and tongue couplings of string insulator units – Dimensions
[5] IEC 60672-1, Ceramic and glass insulating materials – Part 1: Definitions and
classification
[6] IEC 60672-3, Ceramic and glass-insulating materials – Part 3: Specifications for
individual materials
[7] IEC TS 60815-1, Selection and dimensioning of high-voltage insulators intended for
use in polluted conditions – Part 1: Definitions, information and general principles
[8] IEC TS 60815-2:2008, Selection and dimensioning of high-voltage insulators intended
for use in polluted conditions – Part 2: Ceramic and glass insulators for AC systems

_____________
IEC 60433 ®
Edition 4.0 2021-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Insulators for overhead lines with a nominal voltage above 1 000 V – Ceramic
insulators for AC systems – Characteristics of insulator units of the long rod
type
Isolateurs pour lignes aériennes de tension nominale supérieure a 1 000 V –
Isolateurs en céramique pour réseaux à tension alternative – Caractéristiques
des éléments d'isolateurs du type a long fût

– 2 – IEC 60433:2021 © IEC 2021
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 6
4 Characteristics, dimensions and type of long rod insulators . 6
5 Designation and marking . 6
Bibliography . 11

Figure 1 – Long rod insulator with clevis couplings, type C . 10
Figure 2 – Long rod insulator with socket couplings, type B . 10

Table 1 – Specified values for long rod insulators . 8

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INSULATORS FOR OVERHEAD LINES
WITH A NOMINAL VOLTAGE ABOVE 1 000 V –
CERAMIC INSULATORS FOR AC SYSTEMS –
CHARACTERISTICS OF INSULATOR UNITS OF THE LONG ROD TYPE

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
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). 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. 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 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 IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
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 60433 has been prepared by IEC technical committee 36:
Insulators.
This fourth edition cancels and replaces the third edition published in 1998. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) wording in Scope changed from "should" to "are intended to";
b) new normative references added;
c) title of Clause 4 amended, new Note 4 added;
d) Table 1 expanded to include more specified mechanical failing loads.

– 4 – IEC 60433:2021 © IEC 2021
The text of this International Standard is based on the following documents:
FDIS Report on voting
36/498/FDIS 36/500/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.
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.
INSULATORS FOR OVERHEAD LINES
WITH A NOMINAL VOLTAGE ABOVE 1 000 V –
CERAMIC INSULATORS FOR AC SYSTEMS –
CHARACTERISTICS OF INSULATOR UNITS OF THE LONG ROD TYPE

1 Scope
This International Standard is applicable to string insulator units of the long rod type with
insulating parts of ceramic material intended for use in AC overhead power lines with a
nominal voltage greater than 1 000 V and a frequency not greater than 100 Hz. It is also
applicable to insulators of similar design, used in substations.
This document is applicable to ceramic string insulator units of the long rod type, either with a
clevis end fitting at both ends for coupling with a tongue, or with a socket end fitting at both
ends for coupling with a pin ball.
The object of this document is to prescribe specified values for electrical and mechanical
characteristics, and for the principal dimensions of ceramic string insulator units of the long
rod type.
This document is applicable to string insulator uni
...

IEC 60433 ®
Edition 4.0 2021-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Insulators for overhead lines with a nominal voltage above 1 000 V – Ceramic
insulators for AC systems – Characteristics of insulator units of the long rod
type
Isolateurs pour lignes aériennes de tension nominale supérieure a 1 000 V –
Isolateurs en céramique pour réseaux à tension alternative – Caractéristiques
des éléments d'isolateurs du type a long fût

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IEC 60433 ®
Edition 4.0 2021-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Insulators for overhead lines with a nominal voltage above 1 000 V – Ceramic

insulators for AC systems – Characteristics of insulator units of the long rod

type
Isolateurs pour lignes aériennes de tension nominale supérieure a 1 000 V –

Isolateurs en céramique pour réseaux à tension alternative – Caractéristiques

des éléments d'isolateurs du type a long fût

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.080.10; 29.240.20 ISBN 978-2-8322-9204-4

– 2 – IEC 60433:2021 © IEC 2021
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 6
4 Characteristics, dimensions and type of long rod insulators . 6
5 Designation and marking . 6
Bibliography . 11

Figure 1 – Long rod insulator with clevis couplings, type C . 10
Figure 2 – Long rod insulator with socket couplings, type B . 10

Table 1 – Specified values for long rod insulators . 8

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INSULATORS FOR OVERHEAD LINES
WITH A NOMINAL VOLTAGE ABOVE 1 000 V –
CERAMIC INSULATORS FOR AC SYSTEMS –
CHARACTERISTICS OF INSULATOR UNITS OF THE LONG ROD TYPE

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60433 has been prepared by IEC technical committee 36:
Insulators.
This fourth edition cancels and replaces the third edition published in 1998. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) wording in Scope changed from "should" to "are intended to";
b) new normative references added;
c) title of Clause 4 amended, new Note 4 added;
d) Table 1 expanded to include more specified mechanical failing loads.

– 4 – IEC 60433:2021 © IEC 2021
The text of this International Standard is based on the following documents:
FDIS Report on voting
36/498/FDIS 36/500/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.
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.
INSULATORS FOR OVERHEAD LINES
WITH A NOMINAL VOLTAGE ABOVE 1 000 V –
CERAMIC INSULATORS FOR AC SYSTEMS –
CHARACTERISTICS OF INSULATOR UNITS OF THE LONG ROD TYPE

1 Scope
This International Standard is applicable to string insulator units of the long rod type with
insulating parts of ceramic material intended for use in AC overhead power lines with a
nominal voltage greater than 1 000 V and a frequency not greater than 100 Hz. It is also
applicable to insulators of similar design, used in substations.
This document is applicable to ceramic string insulator units of the long rod type, either with a
clevis end fitting at both ends for coupling with a tongue, or with a socket end fitting at both
ends for coupling with a pin ball.
The object of this document is to prescribe specified values for electrical and mechanical
characteristics, and for the principal dimensions of ceramic string insulator units of the long
rod type.
This document is applicable to string insulator units for use on overhead lines situated in
lightly polluted areas, and the creepage distances given in Table 1 have been established
accordingly, using the IEC TS 60815-2 recommendation of 27,8 mm/kV for SPS class.
However, shorter creepage distances are applicable for use in some non-polluted areas. If
specific operating conditions require or allow non-standard (longer or shorter) creepage
distances, the mechanical characteristics as well as the lengths L (see Clause 4) of this
document are intended to be used unless the need for exceptionally long creepage distances
requires values of L greater than those given in Table 1. In the case of special requirements,
e.g. very heavy polluted areas and for other particular or extreme environmental conditions, it
may be necessary for certain dimensions to be changed.
As far as reasonably applicable, this document is also applicable to be applied to similar
insulator units outside the scope of this standard, such as insulators for electric traction lines.
This document does not include tests on insulators and dimensions of end fittings.
Ball and socket couplings are covered by IEC 60120, clevis and tongue couplings by
IEC 60471.
NOTE 1 For the definition of site pollution severity, see applicable part of IEC TS 60815.
NOTE 2 The term "ceramic" is used in this document to refer to porcelain materials and, contrary to North
American practice, does not include glass.
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 60383-1, Insulators for overhead lines with a nominal voltage above 1 000 V – Part 1:
Ceramic or glass insulator units for AC systems – Definitions, test methods and acceptance
criteria
– 6 – IEC 60433:2021 © IEC 2021
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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
long rod insulator
suspension or tension insulator consisting of an approximately cylindrical insulating part
provided with sheds and equipped at the ends with external metal fittings
Note 1 to entry: The insulator is designed in such a manner that the shortest puncture path through solid
insulating material is at least equal to half the arcing distance. Therefore it is a class A insulator according to
IEC 60383-1.
4 Characteristics, dimensions and type of long rod insulators
String insulator units of the long rod type are characterised by the following specified
characteristics:
– the standard lightning impulse withstand voltage (see IEC 60071-1);
– the wet power frequency withstand voltage (see IEC 60071-1);
– the tensile mechanical failing load;
– the maximum nominal length L of the insulator;
– the maximum nominal diameter D of the insulating part;
– the minimum nominal creepage distance;
– the standard coupling.
The corresponding values are specified in Table 1. The minimum nominal creepage distances
are based on a unified specific creepage distance of 27,8 mm/kV for the lowest value of the
highest voltage for equipment corresponding to the specified value of the standard lightning
impulse withstand (in accordance with IEC 60071-1).
NOTE 1 The tolerances given in IEC 60383-1 are applicable to all the dimensions in Table 1, even if the
adjectives "minimum" or "maximum" are used before the term "nominal".
NOTE 2 Dry lightning impulse withstand voltage and wet power frequency withstand voltage are specified in
Table 1 for single unit string insulators. Values of withstand voltages of insulator strings consisting of more than
one unit are not contained in this document.
NOTE 3 The rod diameter is not specified since it depends on the mechanical characteristics of the insulating
material. Information on the definition and classification of ceramic insulating materials can be found in
IEC 60672-1 and IEC 60672-3.
NOTE 4 Examples of shed profile are given in Clause 8, “Choice of profile” of IEC TS 60815-2:2008.
5 Designation and marking
Long rod insulators are designated in Table 1 by the letter L, followed by a figure indicating
the specified mechanical failing load in kilonewtons. Then follows the letter B or C indicating
socket or clevis coupling respectively, followed by the value of the lightning impulse withstand
voltage in kilovolts.
EXAMPLE:
L 160 B 550 indicates:
L: long rod insulator;
160: specified mechanical failing load, tension, 160 kN;
B: socket coupling;
550: dry lightning impulse withstand voltage 550 kV.
The insulators shall be marked either on the upper shed or on the metal parts with the name
or trade mark of the manufacturer and the year of manufacture. In addition, each unit shall be
marked with the specified mechanical failing load, by using the first part of the designation; for
instance, the insulator shall be marked L 160 for the units with 160 kN specified mechanical
failing load.
These markings shall be legible and indelible.
Figure 1 shows a long rod insulator with clevis couplings. Figure 2 shows a long rod insulator
with socket couplings.
– 8 – IEC 60433:2021 © IEC 2021

Table 1 – Specified values for long rod insulators
Coupling B Coupling C
Designation Standard Wet power Specified Maximum Minimum Standard Maximum Standard coupling size
Maximum
lightning frequency mechanical nominal nominal creepage nominal coupling size nominal (coupling pin diameter,
impulse withstand failing load diameter D on distance length L (pin diameter, length L see IEC 60471 –
withstand voltage the insulating (27.8 mm/kV, see IEC 60120) non-preferred
voltage part see Clause 4) sizes in brackets)
kV kV kN mm mm mm mm
L 40 B/C 170 170 70 40 160 576 380 11 400 13L
L 60 B/C 170 170 70 60 160 576 400 11 420 13L
L 100 B/C 170 170 70 100 180 576 450 16 475 19L (16L)
L 100 B/C 250 250 95 100 180 832 580 16 605 19L (16L)
L 100 B/C 325 325 140 100 180 1 160 870 16 900 19L (16 L)
L 100 B/C 450 450 185 100 180 1 968 1 085 16 1 120 19L (16L)
L 100 B/C 550 550 230 100 180 1 968 1 240 16 1 270 19L (16L)
L 120 B/C 325 325 140 120 200 1 160 870 16 905 19L (16L)
L 120 B/C 450 450 185 120 200 1 968 1 085 16 1 120 19L (16L)
L 120 B/C 550 550 230 120 200 1 968 1 240 16 1 275 19L (16L)
L 120 B/C 650 650 275 120 200 2 320 1 430 16 1 465 19L (16L)
L 160 B/C 325 325 140 160 210 1 160 885 20 920 19L
L 160 B/C 450 450 185 160 210 1 968 1 100 20 1 135 19L
L 160 B/C 550 550 230 160 210 1 968 1 255 20 1 290 19L
L 160 B/C 650 650 275 160 210 2 320 1 445 20 1 465 19L
L 210 B/C 325 325 140 210 220 1 160 905 20 940 22L
L 210 B/C 450 450 185 210 220 1 968 1 120 20 1 155 22L
L 210 B/C 550 550 230 210 220 1 968 1 275 20 1 310 22L
L 210 B/C 650 650 275 210 220 2 320 1 465 20 1 500 22L

Coupling B Coupling C
Designation Standard Wet power Specified Maximum Minimum Maximum Standard Maximum Standard coupling size
lightning frequency mechanical nominal nominal creepage nominal coupling size nominal (coupling pin diameter,
impulse withstand failing load diameter D on distance length L (pin diameter, length L see IEC 60471 –
withstand voltage the insulating (27.8 mm/kV, see IEC 60120) non-preferred
voltage part see Clause 4) sizes in brackets)
kV kV kN mm mm mm mm
L 250 B/C 550 550 230 250 230 1 968 1 305 24 1 335 22L
L 250 B/C 650 650 275 250 230 2 320 1 500 24 1 530 22L
L 300 B/C 550 550 230 300 240 1 968 1 330 24 1 365 25L
L 300 B/C 650 650 275 300
...