EN 62135-1:2015

SLOVENSKI STANDARD
01-september-2015
1DGRPHãþD
SIST EN 62135-1:2009
Oprema za uporovno varjenje - 1. del: Varnostne zahteve za zasnovo, izdelavo in
inštalacijo
Resistance welding equipment - Part 1: Safety requirements for design, manufacture and
installation
Widerstandsschweißeinrichtungen - Teil 1: Sicherheitsanforderungen für die
Konstruktion, Herstellung und Errichtung
Matériels de soudage par résistance - Partie 1: Exigences de sécurité pour la
conception, la fabrication et l’installation
Ta slovenski standard je istoveten z: EN 62135-1:2015
ICS:
25.160.30 Varilna oprema Welding equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 62135-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2015
ICS 25.160 Supersedes EN 62135-1:2008
English Version
Resistance welding equipment - Part 1: Safety requirements for
design, manufacture and installation
(IEC 62135-1:2015)
Matériels de soudage par résistance - Partie 1: Exigences Widerstandsschweißeinrichtungen - Teil 1:
de sécurité pour la conception, la fabrication et l'installation Sicherheitsanforderungen für die Konstruktion, Herstellung
(IEC 62135-1:2015) und Errichtung
(IEC 62135-1:2015)
This European Standard was approved by CENELEC on 2015-06-11. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2015 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 62135-1:2015 E
European foreword
The text of document 26/558/FDIS, future edition 2 of IEC 62135-1, prepared by IEC/TC 26 "Electric
welding" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
The following dates are fixed:
(dop) 2016-03-11
• latest date by which the document has to be implemented at
national level by publication of an identical national
standard or by endorsement
(dow) 2018-06-11
• latest date by which the national standards conflicting with
the document have to be withdrawn

This document supersedes EN 62135-1:2008.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such
patent rights.
This standard covers the Principle Elements of the Safety Objectives for Electrical Equipment
Designed for Use within Certain Voltage Limits (LVD - 2006/95/EC).
Endorsement notice
The text of the International Standard IEC 62135-1:2015 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:
IEC 60085 NOTE Harmonized as EN 60085.
IEC 60112 NOTE Harmonized as EN 60112.
IEC 60364 NOTE Harmonized in HD 384 / HD 60364 series (partly modified).
IEC 60990 NOTE Harmonized as EN 60990.
IEC 62135-2 NOTE Harmonized as EN 62135-2.
ISO 5826 NOTE Harmonized as EN ISO 5826.
ISO 5828 NOTE Harmonized as EN ISO 5828.
ISO 8205-1 NOTE Harmonized as EN ISO 8205-1.
ISO 8205-2 NOTE Harmonized as EN ISO 8205-2.
ISO 12100 NOTE Harmonized as EN ISO 12100.
ISO 13732-1 NOTE Harmonized as EN ISO 13732-1.
IEC 13732 NOTE Harmonized in EN 13732 series (not modified).
1) 1)
ISO 14121-1 NOTE Harmonized as EN ISO 14121-1 .

1) Withdrawn.
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
NOTE 1 When an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is
available here: www.cenelec.eu.

Publication Year Title EN/HD Year
IEC 60204-1 (mod) 2005 Safety of machinery - Electrical EN 60204-1 2006
equipment of machines -
- -  + corrigendum Feb. 2010
Part 1: General requirements
IEC 60364-4-41 (mod) 2005 Low-voltage electrical installations - HD 60364-4-41 2007
Part 4-41: Protection for safety -
- -  + corrigendum Jul. 2007
Protection against electric shock
IEC 60364-6 -  Low voltage electrical installations - HD 60364-6 -
Part 6: Verification
IEC 60417-DB -  Graphical symbols for use on - -
equipment
IEC 60445 -  Basic and safety principles for man- EN 60445 -
machine interface, marking and
identification - Identification of
equipment terminals, conductor
terminations and conductors
IEC 60529 -  Degrees of protection provided by EN 60529 -
enclosures (IP Code)
IEC 60664-1 2007 Insulation coordination for equipment EN 60664-1 2007
within low-voltage systems -
Part 1: Principles, requirements and
tests
IEC 60664-3 -  Insulation coordination for equipment EN 60664-3 -
within low-voltage systems -
Part 3: Use of coating, potting or
moulding for protection against pollution
IEC 61140 -  Protection against electric shock - EN 61140 -
Common aspects for installation and
equipment
Publication Year Title EN/HD Year
ISO 669 -  Resistance welding - Resistance - -
welding equipment - Mechanical and
electrical requirements
ISO 13849-1 -  Safety of machinery - Safety-related EN ISO 13849-1 -
parts of control systems -
Part 1: General principles for design

IEC 62135-1 ®
Edition 2.0 2015-05
INTERNATIONAL
STANDARD
colour
inside
Resistance welding equipment –

Part 1: Safety requirements for design, manufacture and installation

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 25.160 ISBN 978-2-8322-2664-3

– 2 – IEC 62135-1:2015 © IEC 2015
CONTENTS
FOREWORD . 6
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 9
4 Environmental conditions . 11
5 Tests . 11
5.1 Test condition . 11
5.2 Measuring instruments . 11
5.3 Type tests . 12
5.4 Routine tests. 12
6 Protection against electric shock . 12
6.1 General . 12
6.2 Insulation . 13
6.2.1 General . 13
6.2.2 Clearances . 13
6.2.3 Creepage distances . 14
6.2.4 Insulation resistance . 16
6.2.5 Dielectric strength . 16
6.2.6 Welding circuit touch current . 18
6.2.7 Liquid cooling . 18
6.3 Protection against electric shock in normal service (direct contact) . 19
6.3.1 General . 19
6.3.2 Rated no-load voltage at the output . 19
6.3.3 Protection provided by barriers or the enclosure . 20
6.3.4 Capacitors . 21
6.3.5 Automatic discharge of input capacitors . 21
6.3.6 Protective conductor current under normal condition. 22
6.3.7 Touch current in normal condition . 22
6.4 Protection against electric shock in case of a fault condition (indirect
contact) . 22
6.4.1 General . 22
6.4.2 Protective provisions for welding circuit . 24
6.4.3 Internal conductors and connections . 36
6.4.4 Touch current in fault condition . 36
6.4.5 DC resistance welding equipment operating at mains frequency . 37
6.4.6 DC resistance welding equipment operating at medium frequency . 37
6.4.7 Continuity of the protective bonding circuit . 37
6.5 Additional user requirements. 38
6.6 Supply voltage . 38
6.7 Conductors of the welding circuit . 38
7 Thermal requirements . 38
7.1 Heating test . 38
7.1.1 Test conditions . 38
7.1.2 Tolerances of the test parameters . 39
7.1.3 Beginning of the heating test . 40
7.1.4 Duration of the test . 40

IEC 62135-1:2015 © IEC 2015 – 3 –
7.2 Temperature measurement . 40
7.2.1 Measurements conditions . 40
7.2.2 Surface temperature sensor . 40
7.2.3 Resistance . 40
7.2.4 Embedded temperature sensor . 41
7.2.5 Determination of the ambient temperature (t ) . 41
a
7.2.6 Determination of cooling liquid temperature (t ) . 41
a
7.2.7 Recording of temperatures . 41
7.3 Limits of temperature rise . 42
7.3.1 Windings . 42
7.3.2 External surfaces . 42
7.3.3 Other components . 44
7.4 Protection from thermal hazards in normal service (direct contact) . 44
7.4.1 General . 44
7.4.2 Identification of hot surfaces . 44
7.4.3 Protection provided by insulation or other barriers . 45
7.4.4 Protection provided by supplemental cooling . 45
8 Abnormal operation . 45
8.1 General requirements . 45
8.2 Stalled fan test . 45
8.3 Cooling system failure . 45
8.4 Overload test . 46
9 Provisions against mechanical hazards . 46
9.1 General . 46
9.2 Risk analysis. 46
9.2.1 General . 46
9.2.2 Ready-to-use equipment as in delivery state . 46
9.2.3 Equipment not ready to use as in delivery state . 46
9.2.4 Equipment not ready for use and designed to be incorporated in more
complex equipment . 47
9.3 Measures . 47
9.3.1 Minimum measures . 47
9.3.2 Additional measures . 47
9.4 Conformity of components . 48
9.5 Starting for manual operated equipment . 48
10 Instructions and markings . 49
10.1 Instructions . 49
10.2 Markings . 49
10.3 Marking of terminals . 49
Annex A (informative) Nominal voltages of supply networks . 51
Annex B (normative) Construction of supply circuit terminals . 52
B.1 Size of terminals . 52
B.2 Spacings between supply circuit terminals . 52
B.3 Connections at the terminals . 53
B.4 Construction of the terminals . 53
B.5 Fixing of the terminals . 53
Annex C (normative) Touch current measurement in fault condition . 54
Annex D (informative) Extrapolation of temperature to time of shutdown . 56

– 4 – IEC 62135-1:2015 © IEC 2015
Annex E (informative) Example of risk analysis and safety level requirement . 57
E.1 General . 57
E.2 Monitored hazards . 57
E.3 General measures . 57
E.4 Typical hazards by type of equipment . 57
E.4.1 General . 57
E.4.2 Spot welding . 58
E.4.3 Projection welding . 59
E.4.4 Seam welding . 60
E.4.5 Butt welding . 60
Annex F (informative) Indirect contact protection in resistance welding equipment . 61
F.1 Protection against indirect contact by automatic disconnection of the supply . 61
F.1.1 General . 61
F.1.2 TN system . 61
F.1.3 TT systems . 62
F.2 Automatic disconnection of supply in single phase a.c. current equipment . 63
F.2.1 TN system . 63
F.2.2 TT systems . 64
F.3 Automatic disconnection of supply in d.c. current equipment operating at
medium frequency (inverter equipment) . 64
F.3.1 TN system . 64
F.3.2 TT systems . 65
Bibliography . 68

Figure 1 – Measurement of welding circuit touch current . 18
Figure 2 – Measurement of rms values . 19
Figure 3 – Example of metal screen between windings of the supply circuit and the
welding circuit . 26
Figure 4 – Example of protective conductor connected directly to the welding circuit
(single-spot, a.c. current equipment) . 27
Figure 5 – Example of protective conductor connected directly to welding circuits
(multi-spot, a.c. current equipment) . 27
Figure 6 – Example of protective conductor connected directly to welding circuits
(medium-frequency equipment) . 28
Figure 7 – Example of protective conductor connected to welding circuits through
impedances . 29
Figure 8 – Example of protective conductor connected to welding circuits through
auto-inductances . 30
Figure 9 – Example of protective conductor connected to welding circuits through
auto-inductances . 30
Figure 10 – Example of current operated RCD (a.c. current equipment) . 31
Figure 11 – Example of current operated RCD (medium-frequency equipment) . 32
Figure 12 – Example of current operated residual current device and voltage relay . 33
Figure 13 – Example of current operated residual current device and safety-voltage
relay . 34
Figure 14 – Example of safety voltage relay . 35
Figure C.1 – Measuring network for weighted touch current . 54

IEC 62135-1:2015 © IEC 2015 – 5 –
Figure C.2 – Diagram for touch current measurement on fault condition at operating
temperature for single-phase connection of appliances other than those of class II . 55
Figure C.3 – Diagram for touch current measurement on fault condition for three-
phase four-wire system connection of appliances other than those of class II . 55
Figure E.1 – Structure of a mounted machine . 58
Figure E.2 – Structure of a hand-held welding gun . 58
Figure E.3 – Structure of projection welding machinery . 59
Figure E.4 – Structure of seam welding machinery . 60
Figure E.5 – Structure of butt welding machinery . 60
Figure F.1 – Principle illustration of insulation fault . 61
Figure F.2 – Illustrations of TN systems . 62
Figure F.3 – Illustrations of TT systems . 63
Figure F.4 – Typical fault current . 65
Figure F.5 – Time-to-voltage reference curve . 67

Table 1 – Minimum clearances for overvoltage category III . 13
Table 2 – Minimum creepage distances . 15
Table 3 – Insulation resistance . 16
Table 4 – Dielectric test voltages . 17
Table 5 – Minimum distance through insulation . 25
Table 6 – Continuity of the protective bonding circuit . 37
Table 7 – Limits of temperature rise for windings . 42
Table 8 – Limits of temperature rise for external surfaces of hand-held equipment. 43
Table 9 – Limits of temperature rise for external surfaces of hand-guided equipment . 43
Table 10 – Limits of temperature rise for external surfaces of fixed equipment . 43
Table B.1 – Range of conductor dimensions to be accepted by the supply circuit
terminals . 52
Table B.2 – Spacing between supply circuit terminals . 53

– 6 – IEC 62135-1:2015 © IEC 2015
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
RESISTANCE WELDING EQUIPMENT –

Part 1: Safety requirements for design,
manufacture and installation
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 62135-1 has been prepared by IEC technical committee 26:
Electric welding.
This second edition cancels and replaces the first edition published in 2008. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
– creepage distances for pollution degree 4 are no longer valid (see Table 2);
– insulation requirements for Class II equipment are defined (see Table 3);
– dielectric test voltage interpolation restriction lower limit is changed to 220 V and
interpolation for control and welding circuit is clarified (see Table 4);
– maximum temperature for insulation systems are reviewed in accordance with current
edition of IEC 60085 (see Table 7);

IEC 62135-1:2015 © IEC 2015 – 7 –
– marking of terminals is defined (see 10.3);
– table for nominal voltages of supply networks is changed adopting Table B.2 of
IEC 60664-1:2007 in place of the Table B.1 values referenced in the previous edition to
provide for equipment to be connected to both earthed and unearthed systems. The
change impacts the creepage and clearance distance requirements for some supply
voltage ratings (see Annex A);
– touch current in fault condition are measurement procedures are clarified (see 6.4.4 and
Annex C).
– welding circuit touch current is defined (see 6.2.6);
– touch current in normal condition are clarified and moved in protection against electric
shock in normal service (see 6.3.7);
– heating test conditions are clarified (see 7.1.1);
– external surface temperature rise limitation is changed (see 7.3.2).
The text of this standard is based on the following documents:
FDIS Report on voting
26/558/FDIS 26/570/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.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The list of all the parts of the IEC 62135 series, under the general title Resistance welding
equipment, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC website 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.
A bilingual version of this publication may be issued at a later date.

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.
– 8 – IEC 62135-1:2015 © IEC 2015
RESISTANCE WELDING EQUIPMENT –

Part 1: Safety requirements for design,
manufacture and installation
1 Scope
This part of IEC 62135 applies to equipment for resistance welding and allied processes and
includes single and multiple welding stations which may be manually or automatically loaded
and/or started.
This part of IEC 62135 covers stationary and portable equipment.
This part of IEC 62135 specifies electrical safety requirements for design, manufacture and
installation. It does not cover all non-electrical safety requirements (e.g. noise, vibration).
This part of IEC 62135 does not include electromagnetic compatibility (EMC) requirements,
which are included in IEC 62135-2.
To comply with this standard, all safety risks involved in loading, feeding, operating and
unloading the equipment, where applicable, should be assessed and the requirements of
related standards should be observed.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60204-1:2005, Safety of machinery – Electrical equipment of machines – Part 1: General
requirements
IEC 60364-4-41:2005, Low-voltage electrical installations – Part 4-41: Protection for safety –
Protection against electric shock
IEC 60364-6, Low-voltage electrical installations – Part 6: Verification
IEC 60417-DB:2011 , Graphical symbols for use on equipment
IEC 60445, Basic and safety principles for man-machine interface, marking and identification
– Identification of equipment terminals, conductor terminations and conductors
IEC 60529, Degrees of protection provided by enclosures (IP Code)
IEC 60664-1:2007, Insulation coordination for equipment within low-voltage systems – Part 1:
Principles, requirements and tests
___________
“DB” refers to the IEC on-line database.

IEC 62135-1:2015 © IEC 2015 – 9 –
IEC 60664-3, Insulation coordination for equipment within low-voltage systems – Part 3: Use
of coating, potting or moulding for protection against pollution
IEC 61140, Protection against electric shock – Common aspects for installation and
equipment
ISO 669, Resistance welding – Resistance welding equipment – Mechanical and electrical
requirements
ISO 13849-1, Safety of machinery – Safety-related parts of control systems – Part 1: General
principles for design
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 669, IEC 60664-1
and IEC 60204-1, as well as the following, apply.
3.1
equipment for resistance welding and allied processes
equipment associated with carrying out the processes of resistance welding or allied
processes consisting of, for example, power source, electrodes, tooling and associated
control equipment
Note 1 to entry: It may be a separate unit or part of a complex machine.
Note 2 to entry: The term "resistance welding equipment" is used in the following text.
3.2
processes allied to resistance welding
processes carried out on machines comparable to resistance welding equipment considered
as allied to resistance welding, for example, resistance brazing, soldering or heating
3.3
type test
test of one or more devices made to a given design, to check if these devices comply with the
requirements of the standard concerned
[SOURCE: IEC 60050-851:2008, 851-12-05]
3.4
routine test
test made on each individual device during or after manufacture to check if it complies with
the requirements of the standard concerned or the criteria specified
[SOURCE: IEC 60050-851:2008, 851-12-06]
3.5
welding circuit
conductive material through which the welding current is intended to flow
3.6
control circuit
circuit for the operational control of welding equipment, and/or for protection of the power
circuits
– 10 – IEC 62135-1:2015 © IEC 2015
3.7
conventional value
standardized value that is used as a measure of a parameter for the purposes of comparison,
calibration, testing, etc.
Note 1 to entry: Conventional values do not necessarily apply during the actual welding process.
3.8
rated value
value assigned, generally by the manufacturer, for a specified operating condition of a
component, device or equipment
3.9
rating
set of rated values and operating conditions
3.10
hand-held equipment
resistance welding equipment with built-in or external transformer, which is intended to be
held in the hand during use, suspended or not
3.11
portable equipment
resistance welding equipment that is connected to the mains supply by means of a plug.
3.12
stationary equipment
resistance welding equipment permanently connected to the mains supply
3.13
material group
materials are separated into four groups by their comparative tracking index (CTI) values
Note 1 to entry: The groups are as follows:
Material group I 600 ≤ CTI
Material group II 400 ≤ CTI < 600
Material group IIIa 175 ≤ CTI < 400
Material group IIIb 100 ≤ CTI < 175
The CTI values above refer to values in accordance with IEC 60112.
Note 2 to entry: For inorganic insulating materials, for example, glass or ceramics, which do not track, creepage
distances need not be greater than their associated clearance for the purpose of insulation coordination.
3.14
thermal equilibrium
state reached when the observed temperature rise of any part of the welding equipment does
not exceed 2 K/h
3.15
thermal protection
system intended to ensure the protection of all or part of the welding equipment against
excessive temperatures resulting from certain conditions of thermal overload
Note 1 to entry: It is capable of being reset (either manually or automatically) when the temperature falls to the
reset value.
IEC 62135-1:2015 © IEC 2015 – 11 –
3.16
supply circuit
input circuit
conductive material of the power source through which the supply current is intended to flow
3.17
general visual inspection
inspection by eye to verify that there are no apparent discrepancies with respect to provisions
of the standard concerned
3.18
working voltage
highest r.m.s. value of the a.c. or d.c. voltage across any particular insulation which can occur
when the equipment is supplied at rated voltage
Note 1 to entry: Transients are disregarded.
Note 2 to entry: Both open-circuit conditions and normal operating conditions are taken into account.
4 Environmental conditions
Resistance welding equipment intended for indoor use and complying with this standard shall
be safe to operate when the following environmental conditions prevail:
a) range of ambient air temperature:
during operation: 5 °C to 40 °C;
b) relative humidity of the air:
up to 50 % at 40 °C;
up to 90 % at 20 °C.
c) ambient air, free from abnormal amounts of dust, acids, corrosive gases or substances
etc. other than those generated by the welding process.
d) altitude above sea-level up to 1 000 m;
e) temperature of the cooling medium does not exceed:
1) in the case of a liquid: 30 °C at the inlet;
2) in the case of the ambient air: 40 °C.
NOTE Different environmental conditions can be agreed upon between the manufacturer and the purchaser and
the resulting welding equipment is marked accordingly. Examples of these conditions are: outdoor use, different
altitude, different temperature of cooling medium, high humidity, unusually corrosive fumes, steam, excessive oil
vapour, abnormal vibration or shock, excessive dust, unusual sea coast or shipboard conditions.
5 Tests
5.1 Test condition
The tests shall be carried out on new, dry and completely assembled resistance welding
equipment at an ambient air temperature between 10 °C and 40 °C. It is recommended that
the thermal tests be carried out at 40 °C. Liquid-cooled resistance welding equipment shall be
tested with liquid conditions as specified by the manufacturer.
5.2 Measuring instruments
The accuracy of measuring instruments shall be as follows.
a) electrical measuring instruments: class 1 (±1 % of full-scale reading), except for the
measurement of insulation resistance and dielectric strength where the accuracy of the
instruments is not specified, but shall be taken into account for the measurement;

– 12 – IEC 62135-1:2015 © IEC 2015
b) instruments for measuring welding current: class 5;
c) temperature measuring instruments: ±2 K.
5.3 Type tests
Unless otherwise specified, the tests in this standard are type tests.
The resistance welding equipment shall be tested with all ancillary equipment fitted that could
affect the test results.
All type tests shall be carried out on the same resistance welding equipment except where it
is specified that a test may be carried out on another resistance welding equipment.
As a condition of conformity, the type tests given below shall be carried out in the following
sequence:
a) general visual inspection, see 3.17;
b) insulation resistance, see 6.2.4 (preliminary check);
c) protection provided by the enclosure, see 6.3.3;
d) insulation resistance, see 6.2.4;
e) dielectric strength, see 6.2.5;
f) general visual inspection, see 3.17.
The other tests included in this standard and not listed here may be carried out in any
convenient sequence.
5.4 Routine tests
All routine tests shall be carried out on each resistance welding equipment. The following
sequence is recommended:
a) general visual inspection, see 3.17;
b) continuity of the protective circuit, see 6.4.7;
c) dielectric strength, see 6.2.5;
d) no-load voltage, see 6.3.2;
e) test to ensure rated minimum and maximum output values in accordance with ISO 669;
f) general visual inspection, see 3.17.
6 Protection against electric shock
6.1 General
Hazardous-live-parts shall not be accessible and accessible conductive parts shall not be
hazardous live
– either under normal condition
...