IEC 60974-4:2025
(Main)Arc welding equipment - Part 4: Periodic inspection and testing
Arc welding equipment - Part 4: Periodic inspection and testing
IEC 60974-4:2025 specifies test procedures for periodic inspection and, after repair, to ensure electrical safety. These test procedures are also applicable for maintenance. This document is applicable to power sources for arc welding and allied processes designed in accordance with IEC 60974-1 or IEC 60974-6. Stand-alone ancillary equipment designed in accordance with other parts of IEC 60974 can be tested in accordance with relevant requirements of this part of IEC 60974. This document includes requirements for battery-powered arc welding power sources, which are given in Annex D.
NOTE 1 The welding power source can be tested with any ancillary equipment fitted that can affect the test results.
This document is not applicable to testing of new power sources or engine-driven power sources.
NOTE 2 For a power source not built in accordance with IEC 60974-1, see Annex C.
This fourth edition cancels and replaces the third edition published in 2016. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- examples for the measurements in respect of EN 50699,
- consideration of measuring equipment in respect of IEC 61557 series,
- more determinations of no-load voltage for welding equipment built according to IEC 60974-1:1998 and IEC 60974-1:1998/AMD1:2000 or earlier,
- new Annex D providing additional information to be considered when testing battery-powered welding power sources and connected chargers.
Matériel de soudage à l'arc - Partie 4: Inspection et essais périodiques
L'IEC 60974-4:2025 spécifie les procédures d'essai pour l'inspection périodique, afin d'assurer la sécurité électrique après réparation. Ces procédures d'essai s'appliquent également à la maintenance. Le présent document s'applique aux sources de courant pour le soudage à l'arc et les techniques connexes conçues conformément à l'IEC 60974-1 ou l'IEC 60974-6. Les équipements auxiliaires indépendants conçus conformément à d'autres parties de l'IEC 60974 peuvent être soumis à l'essai conformément aux exigences correspondantes de la présente partie de l'IEC 60974. Le présent document inclut des exigences concernant les sources de courant de soudage à l'arc sur batterie, qui figurent à l'Annexe D.
NOTE 1 La source de courant de soudage peut être soumise à l'essai avec tout équipement auxiliaire monté qui peut influencer les résultats d'essai.
Le présent document ne s'applique pas aux essais des nouvelles sources de courant ou aux groupes électrogènes.
NOTE 2 Pour une source de courant qui n'est pas conçue conformément à l'IEC 60974-1, voir Annexe C.
Cette quatrième édition annule et remplace la troisième édition parue en 2016. Elle constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
- exemple de mesurages en référence à l'EN 50699,
- prise en compte de l'équipement de mesure en référence à la série IEC 61557,
- autres déterminations de la tension à vide pour le matériel de soudage construit conformément à l'IEC 60974-1:1998 et l'IEC 60974-1:1998/AMD1:2000 ou une édition antérieure;
- nouvelle Annexe D contenant des informations supplémentaires à prendre en compte lors des essais des sources de courant de soudage sur batterie et des chargeurs connectés.
General Information
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Standards Content (Sample)
IEC 60974-4 ®
Edition 4.0 2025-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Arc welding equipment –
Part 4: Periodic inspection and testing
Matériel de soudage à l'arc –
Partie 4: Inspection et essais périodiques
ICS 25.160 ISBN 978-2-8327-0462-2
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– 2 – IEC 60974-4:2025 © IEC 2025
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 General requirements . 9
4.1 Qualification of personnel . 9
4.2 Test conditions . 9
4.3 Measuring instruments . 9
4.4 PERIODIC INSPECTION and testing. 9
4.5 MAINTENANCE . 9
4.6 Test after REPAIR . 10
4.7 Test sequence . 10
5 Protection against electrical shock . 10
5.1 VISUAL INSPECTION . 10
5.2 Continuity of the protective circuit . 11
5.3 Insulation resistance . 11
5.4 WELDING CIRCUIT TOUCH CURRENT . 12
5.5 TOUCH CURRENT in normal condition . 13
5.6 Protective conductor current . 14
5.7 NO-LOAD VOLTAGE (U ) . 15
6 Functional test . 17
6.1 General . 17
6.2 Supply-circuit on/off switching device . 17
6.3 Voltage-reducing device. 17
6.4 Magnetic gas valve . 17
6.5 Signal and control lamps . 17
7 Documentation . 18
7.1 Test report . 18
7.2 Labelling . 18
Annex A (informative) Checklist for the VISUAL INSPECTION . 19
Annex B (informative) Example of a test report after REPAIR . 20
Annex C (informative) Equipment not built in accordance with current IEC 60974-1 . 21
C.1 Welding equipment not built in accordance with IEC 60974-1 . 21
C.2 Determination of NO-LOAD VOLTAGE for welding equipment built according to
IEC 60974-1:1998 and IEC 60974-1:1998/AMD1:2000 or earlier . 21
Annex D (normative) Battery-powered WELDING POWER SOURCES . 22
D.1 General . 22
D.2 Protection against electrical shock . 22
D.2.1 VISUAL INSPECTION . 22
D.2.2 Continuity of the protective circuit . 23
D.2.3 Insulation resistance . 23
D.2.4 WELDING CIRCUIT TOUCH CURRENT. 23
D.2.5 TOUCH CURRENT in normal condition . 23
D.2.6 Protective conductor current . 23
D.2.7 NO-LOAD VOLTAGE (U ) . 23
D.3 Functional tests . 23
Bibliography . 24
Figure 1 – Example for the measurement of insulation resistance . 12
Figure 2 – Example for the measurement of WELDING CIRCUIT TOUCH CURRENT . 13
Figure 3 – Example for the measurement of TOUCH CURRENT in normal condition . 13
Figure 4 – Principles of protective conductor current measurement for single phase
equipment . 15
Figure 5 – Measurement of RMS values. 16
Figure 6 – Measurement of peak values . 16
Table 1 – Test sequence on used arc welding equipment . 10
Table 2 – Insulation resistance . 11
Table 3 – Allowable NO-LOAD VOLTAGEs depending on the environment . 15
– 4 – IEC 60974-4:2025 © IEC 2025
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ARC WELDING EQUIPMENT –
Part 4: Periodic inspection and testing
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
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
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the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC 60974-4 has been prepared by IEC technical committee 26: Electric welding. It is an
International Standard.
This fourth edition cancels and replaces the third edition published in 2016. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
• examples for the measurements in respect of EN 50699,
• consideration of measuring equipment in respect of IEC 61557 series,
• more determinations of NO-LOAD VOLTAGE for welding equipment built according to
IEC 60974-1:1998 and IEC 60974-1:1998/AMD1:2000 or earlier,
• new Annex D providing additional information to be considered when testing battery-
powered WELDING POWER SOURCES and connected chargers.
The text of this International Standard is based on the following documents:
Draft Report on voting
26/769/FDIS 26/777/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
The list of all the parts of the IEC 60974 series, under the general title Arc welding equipment,
can be found on the IEC website.
In this document, the following print types are used:
• conformity statements: in italic type.
• terms defined in Clause 3: in SMALL ROMAN CAPITALS.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
– 6 – IEC 60974-4:2025 © IEC 2025
ARC WELDING EQUIPMENT –
Part 4: Periodic inspection and testing
1 Scope
This part of IEC 60974 specifies test procedures for PERIODIC INSPECTION and, after REPAIR, to
ensure electrical safety. These test procedures are also applicable for MAINTENANCE.
This document is applicable to power sources for arc welding and allied processes designed in
accordance with IEC 60974-1 or IEC 60974-6. Stand-alone ancillary equipment designed in
accordance with other parts of IEC 60974 can be tested in accordance with relevant
requirements of this part of IEC 60974.
This document includes requirements for battery-powered ARC WELDING POWER SOURCES, which
are given in Annex D.
NOTE 1 The WELDING POWER SOURCE can be tested with any ancillary equipment fitted that can affect the test
results.
This document is not applicable to testing of new power sources or engine-driven power
sources.
NOTE 2 For a power source not built in accordance with IEC 60974-1, see Annex C.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60050-151, International Electrotechnical Vocabulary (IEV) – Part 151: Electrical and
magnetic devices
IEC 60974-1:2021, Arc welding equipment – Part 1: Welding power sources
IEC 60974-6:2015, Arc welding equipment – Part 6: Limited duty equipment
IEC 61140, Protection against electric shock – Common aspects for installation and equipment
IEC 61557-2:2019, Electrical safety in low voltage distribution systems up to 1 000 V AC and
1 500 V DC – Equipment for testing, measuring or monitoring of protective measures – Part 2:
Insulation resistance
IEC 61557-4:2019, Electrical safety in low voltage distribution systems up to 1 000 V AC and
1 500 V DC – Equipment for testing, measuring or monitoring of protective measures – Part 4:
Resistance of earth connection and equipotential bonding
IEC 61557-16:2023, Electrical safety in low voltage distribution systems up to 1 000 V AC and
1 500 V DC – Equipment for testing, measuring or monitoring of protective measures – Part 16:
Equipment for testing the effectiveness of the protective measures of electrical equipment
and/or medical electrical equipment
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-151,
IEC 60974-1 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1
WELDING POWER SOURCE
ARC WELDING POWER SOURCE
equipment for supplying current and voltage and having the required characteristics suitable
for arc welding and allied processes
Note 1 to entry: A WELDING POWER SOURCE can also supply services to other equipment and auxiliaries for example
auxiliary power, cooling liquid, consumable arc welding electrode and gas to shield the arc and the welding area.
[SOURCE: IEC 60050-851:2008, 851-13-01]
3.2
EXPERT
person who can judge the work assigned and recognize possible hazards on the basis of
professional training, knowledge, experience and knowledge of the relevant equipment
Note 1 to entry: Several years of practice in the relevant technical field may be taken into consideration in
assessment of professional training.
[SOURCE: IEC 60050-851:2008, 851-11-10]
3.3
INSTRUCTED PERSON
person informed about the tasks assigned and about the possible hazards involved in neglectful
behaviour
Note 1 to entry: If necessary, the person has undergone some training.
[SOURCE: IEC 60050-851:2008, 851-11-13]
3.4
PERIODIC INSPECTION
inspection of all equipment, systems and installations carried out on a routine basis
[SOURCE: IEC 60050-426:2020, 426-14-07]
3.5
MAINTENANCE
combination of all technical and management actions intended to retain an item in, or restore it
to, a state in which it can perform as required
Note 1 to entry: Management is assumed to include supervision activities.
[SOURCE: IEC 60050-192:2015, 192-06-01]
– 8 – IEC 60974-4:2025 © IEC 2025
3.6
REPAIR
direct action taken to effect restoration
Note 1 to entry: REPAIR includes fault localization (192-06-19), fault diagnosis (192-06-20); fault correction (192-06-
21); and function checkout (192-06-22).
[SOURCE: IEC 60050-192:2015, 192-06-14]
3.7
NO-LOAD VOLTAGE
voltage, exclusive of any arc striking or arc stabilizing voltage, between the accessible output
terminals of a WELDING POWER SOURCE when the WELDING CIRCUIT is open but energized
[SOURCE: IEC 60050-851:2008, 851-12-24, modified – "but energized" has been added.]
3.8
TOUCH CURRENT
electric current passing through a human body or through livestock when it touches one or
more accessible parts of an installation or of equipment
Note 1 to entry: TOUCH CURRENT is measured by using a measuring network that simulates the impedance of the
human body.
[SOURCE: IEC 60050-195:2021, 195-05-21, modified – A note to entry has been added.]
3.9
VISUAL INSPECTION
inspection by eye to verify that there are no apparent discrepancies with respect to provisions
of the standard concerned
[SOURCE: IEC 60050-851:2008, 851-11-11]
3.10
WELDING CIRCUIT
conductive material through which the WELDING CURRENT is intended to flow
Note 1 to entry: In arc welding, the arc is a part of the WELDING CIRCUIT.
Note 2 to entry: In certain arc welding processes, the welding arc can be established between two electrodes. In
such a case, the workpiece is not necessarily a part of the WELDING CIRCUIT.
[SOURCE: IEC 60050-851:2008, 851-14-10, modified – "may" has been changed to "can".]
3.11
WELDING CURRENT
current delivered by a WELDING POWER SOURCE during welding
Note 1 to entry: This entry revises IEC 60050-851:2008, 851-12-28, which will be updated.
3.12
ENVIRONMENT WITH INCREASED RISK OF ELECTRIC SHOCK
environment where the probability of electric shock by arc welding is increased in relation to
normal arc welding conditions
Note 1 to entry: Such environments are found, for example:
a) in locations in which freedom of movement is restricted, so that the operator is forced to perform the welding in
a cramped (for example kneeling, sitting, lying) position with physical contact with conductive parts,
b) in locations which are fully or partially limited by conductive elements, and in which there is a high probability of
unavoidable or accidental contact by the operator,
c) in wet or damp or hot locations where humidity or perspiration considerably reduces the skin resistance of the
human body and the insulating properties of accessories.
Note 2 to entry: This entry revises IEC 60050-851:2008, 851-15-09, which will be updated.
4 General requirements
4.1 Qualification of personnel
Tests of welding equipment can be hazardous and shall be carried out by an EXPERT or an
INSTRUCTED PERSON in the field of electrical REPAIR, preferably also familiar with welding, cutting
and allied processes.
NOTE INSTRUCTED PERSONS are considered qualified for simple periodic testing and MAINTENANCE provided the
equipment enclosure can remain closed. Hazardous voltages and currents inside the equipment enclosure can cause
shock, burn or death. Only an EXPERT can open the equipment.
4.2 Test conditions
Tests shall be carried out at an ambient air temperature between 10 °C and 40 °C on dry and
cleaned welding equipment. Other temperatures may be used when environmental limit
requirements are met by both the test equipment and the WELDING POWER SOURCE.
Unless otherwise specified by the manufacturer, the equipment shall be supplied by a rated
supply voltage with a tolerance of ±10 %.
4.3 Measuring instruments
The accuracy of measuring instruments shall be class 2.5 (±2,5 % of full-scale reading) as a
minimum, except for the measurement of insulation resistance, where the accuracy of the
instruments is not specified but shall be taken into account for the measurement.
The test equipment used for the tests shall be calibrated in regular intervals taking into account
the information given by the manufacturer.
4.4 PERIODIC INSPECTION and testing
The PERIODIC INSPECTION and testing specified in Table 1 shall be carried out.
Tests shall be documented in a test report in accordance with 7.1.
During the tests, complementary instructions from the manufacturer shall be followed.
4.5 MAINTENANCE
The manufacturer's MAINTENANCE schedule and instructions shall be followed.
Tests shall be documented in a test report in accordance with 7.1.
– 10 – IEC 60974-4:2025 © IEC 2025
4.6 Test after REPAIR
After REPAIR or replacement of a component which restores a welding or cutting function, an
EXPERT shall select appropriate tests, as specified in Table 1.
Tests shall be documented in a test report in accordance with 7.1.
During the tests, complementary instructions from the manufacturer shall be observed (for
example, circuit diagrams, spare part list, functional test of WELDING POWER SOURCE and
ancillary equipment, etc.).
4.7 Test sequence
The test sequence is given in Table 1.
Table 1 – Test sequence on used arc welding equipment
PERIODIC INSPECTION and testing Test after REPAIR
a) VISUAL INSPECTION in accordance with 5.1 a) VISUAL INSPECTION in accordance with 5.1
b) Electrical test: b) Electrical test:
– protective conductor resistance in accordance – protective conductor resistance in accordance
with 5.2 with 5.2
– insulation resistance in accordance with 5.3 – insulation resistance in accordance with 5.3
(Additionally, the following tests are (Additionally, the following tests are
recommended: WELDING CIRCUIT TOUCH CURRENT recommended: WELDING CIRCUIT TOUCH CURRENT
in accordance with 5.4, TOUCH CURRENT in in accordance with 5.4, TOUCH CURRENT in
a a
in accordance with 5.5 and in accordance with 5.5 and
normal condition normal condition
protective conductor current in accordance with protective conductor current in accordance with
5.6) 5.6)
– NO-LOAD VOLTAGE in accordance with 5.7 – NO-LOAD VOLTAGE in accordance with 5.7
c) Functional test: c) Functional test:
– no requirement – function in accordance with 6.1
– supply-circuit on/off switching device in
accordance with 6.2
– voltage-reducing device in accordance with 6.3
– magnetic gas valve in accordance with 6.4
– signal and control lamps in accordance with 6.5
d) Documentation in accordance with Clause 7 d) Documentation in accordance with Clause 7
a
Only if there are accessible conductive surfaces not connected to the protective circuit.
5 Protection against electrical shock
5.1 VISUAL INSPECTION
VISUAL INSPECTION shall be carried out in accordance with the conditions of use of welding
equipment and the manufacturer's instructions.
An example of items for a VISUAL INSPECTION is given in Annex A.
NOTE Accessible conductive parts can be identified for testing during VISUAL INSPECTION.
5.2 Continuity of the protective circuit
For mains-powered welding equipment of protection class I, including ancillary equipment (for
example, cooling system) having mains connecting cables up to a length of 5,0 m, the maximum
measured protective conductor resistance shall not exceed 0,3 Ω.
For cables longer than 5,0 m, the permissible value of the protective conductor resistance is
increased by 0,1 Ω per additional 7,5 m cable. The maximum permissible value of the protective
conductor resistance is 1 Ω.
Conformity shall be checked by measuring the resistance between the protective conductor
contact at the plug and exposed conductive parts with testing equipment according to
IEC 61557-4 or IEC 61557-16.
During the measurement, the cables shall be bent, flexed or twisted along the whole length,
especially in the vicinity of cable entries into the enclosure, in order to detect interruptions in
the protective conductor.
NOTE Flexing is not required for permanently connected equipment where the conductor is not accessible. A
minimum measuring current of 10 A, can be utilized instead of bending and flexing to identify faults.
5.3 Insulation resistance
The insulation resistance shall not be less than the values given in Table 2.
Table 2 – Insulation resistance
a
Measurement Resistance Insulation
Supply circuit to WELDING CIRCUIT 5,0 MΩ Double or reinforced
WELDING CIRCUIT to protective circuit 2,5 MΩ Basic
Supply circuit to protective circuit 2,5 MΩ Basic
b
Supply circuit of Class II equipment to 5,0 MΩ Double or reinforced
accessible surfaces
a
Control circuits are tested together with the circuit to which they are galvanically connected. Accessible control
circuits separated from all other circuits are tested according to the manufacturer's specification.
b
For measurement to accessible non-conductive surfaces, such surfaces shall be considered to be covered by
metal foil.
Conformity shall be checked by the stabilized measurement of the insulation resistance by
application of a DC voltage of 500 V with a circuit as shown in Figure 1 with testing equipment
according to IEC 61557-2 or IEC 61557-16.
During the measurement, torches shall be disconnected, solid-state electronic components and
their protective devices may be short-circuited, and liquid cooling units shall be tested without
liquid.
– 12 – IEC 60974-4:2025 © IEC 2025
SOURCE: EN 50699:2020. Reproduced with the permission of © CENELEC.
Figure 1 – Example for the measurement of insulation resistance
5.4 WELDING CIRCUIT TOUCH CURRENT
The TOUCH CURRENT between the WELDING CIRCUIT connections and the protective conductor
terminal shall not exceed 10 mA RMS.
Conformity shall be checked by VISUAL INSPECTION and measurement of the TOUCH CURRENT
with a circuit as shown in Figure 2 at the rated supply voltage(s) and no-load condition.
The measuring network shall be connected as shown in Figure 2 separately to each WELDING
connection.
CIRCUIT
SOURCE: EN 50699:2020. Reproduced with the permission of © CENELEC.
NOTE For class II equipment, the PE-terminal of earthed supply network is used.
Figure 2 – Example for the measurement of WELDING CIRCUIT TOUCH CURRENT
5.5 TOUCH CURRENT in normal condition
The TOUCH CURRENT for accessible conductive surfaces, not connected to the protective circuit,
shall not exceed 0,5 mA RMS under normal conditions.
SOURCE: EN 50699:2020. Reproduced with the permission of © CENELEC.
Figure 3 – Example for the measurement of TOUCH CURRENT in normal condition
– 14 – IEC 60974-4:2025 © IEC 2025
Conformity shall be checked as shown in Figure 3 with testing equipment according to
IEC 61557-16.
a) The WELDING POWER SOURCE is:
– isolated from the ground plane,
– supplied by the highest rated supply voltage,
b) the WELDING CIRCUIT is in the no-load condition,
c) interference suppression capacitors are not disconnected.
5.6 Protective conductor current
For class I equipment, the protective conductor current shall not exceed 10 mA RMS except for
equipment with permanent connection by a reinforced protective conductor in accordance with
IEC 61140.
Equipment for permanent connection with a reinforced protective conductor may have a leakage
current up to 5 % of the rated supply current per phase.
Conformity shall be checked using the measuring circuit as shown in Figure 4 with testing
equipment according to IEC 61557-16 under the following conditions:
a) the WELDING POWER SOURCE is:
– isolated from the ground plane for direct measurement,
– supplied by the highest rated supply voltage,
– not connected to the protective earth except through measurement components,
b) the WELDING CIRCUIT is in the no-load condition,
c) interference suppression capacitors shall not be disconnected.
The measurement of the protective conductor current may be performed directly or in the form
of a difference current measurement (see Figure 4a) and Figure 4b)). The tolerance of the
component values in the measurement circuit shall not exceed ±5 %.
Equipment for permanent connection with a reinforced protective conductor shall be tested
according to the manufacturer's specification.
a) Principle of direct measurement b) Principle of measurement according to the difference
current procedure with possible earth connection
Figure 4 – Principles of protective conductor current measurement
for single phase equipment
5.7 NO-LOAD VOLTAGE (U )
The measured NO-LOAD VOLTAGE shall not exceed the values given in Table 3 when the power
source is supplied at rated supply voltage and frequency. The measured NO-LOAD VOLTAGE
NO-LOAD VOLTAGE U (e. g. given in rating
should not be outside of a range of ±15 % of rated
plate) unless otherwise specified in the instructions.
Table 3 – Allowable NO-LOAD VOLTAGEs depending on the environment
Working conditions NO-LOAD VOLTAGE
ENVIRONMENT WITH INCREASED RISK OF ELECTRIC SHOCK marked by DC 113 V peak
AC 68 V peak and 48 V RMS
Environment without increased risk of electric shock DC 113 V peak
AC 113 V peak and 80 V RMS
Mechanically held torches with increased protection for the operator DC 141 V peak
AC 141 V peak and 100 V RMS
Plasma cutting DC 500 V peak
Before testing, arc striking and stabilizing devices shall, if necessary, be removed or by-passed
according to the manufacturer's instructions (see also instructions for use or manufacturer's
testing instructions).
The NO-LOAD VOLTAGE is measured between welding output terminals. If this is not possible for
NO-LOAD VOLTAGE is measured between the torch and WELDING
safety or control reasons, the
CURRENT return cable connection. This test is not required for plasma cutting power sources.
– 16 – IEC 60974-4:2025 © IEC 2025
If rated reduced NO-LOAD VOLTAGE (U ) or rated switched NO-LOAD VOLTAGE (U ) are defined on
R S
the rating plate, U or U shall be measured instead of U .
R S 0
If the power source in question was built according to IEC 60974-1:1998 (withdrawn) and
IEC 60974-1:1998/AMD1:2000 (withdrawn) or earlier, the procedure according to Annex C can
be considered.
Conformity shall be checked with testing equipment by measurement of
a) RMS values
A true RMS meter shall be used together with a resistor of (5 ± 0,25) kΩ, connected across
the WELDING CIRCUIT terminals as shown in Figure 5:
Key
U NO-LOAD VOLTAGE
V true RMS voltmeter
Figure 5 – Measurement of RMS values
b) peak values
To obtain reproducible measurements of peak values, a stabilized measurement with a
circuit as shown in Figure 6 is used.
Key
U NO-LOAD VOLTAGE
V voltmeter
1 diode 1N4007 or similar
Figure 6 – Measurement of peak values
The voltmeter shall indicate mean values. The measurement range chosen shall be as near as
possible to the actual value of the NO-LOAD VOLTAGE. The voltmeter shall have an internal
resistance of at least 1 MΩ.
The tolerance of the component values in the measurement circuit shall not exceed ±5 %. The
minimum power for the resistor of 0,2 kΩ is 65 W. The rheostat shall withstand a current value
of 0,6 A. The capacitors shall have a minimum voltage rating of 200 V.
6 Functional test
6.1 General
Each safety-related function judged as relevant by the EXPERT or INSTRUCTED PERSON shall be
checked for correct operation.
WELDING
Conformity shall be checked by operating the device and by checking whether the
POWER SOURCE operates correctly.
6.2 Supply-circuit on/off switching device
Where an integral supply-circuit on/off switching device (for example, switch, contactor or
circuit-breaker) is fitted, this shall:
a) open or close all ungrounded mains conductors,
b) clearly indicates whether the circuit is open or closed.
Conformity shall be checked by VISUAL INSPECTION and measurement.
6.3 Voltage-reducing device
Where a voltage-reducing device is fitted, it shall be checked for correct operation.
Conformity shall be checked by measurement of reduced NO-LOAD VOLTAGE (see 5.7) and VISUAL
INSPECTION of indicator in load and no-load condition.
6.4 Magnetic gas valve
Each magnetic gas valve (for example, TIG, MIG/MAG, plasma power sources), shall be
checked for correct operation.
Conformity shall be checked by VISUAL INSPECTION and the following operations or by a test
specified by the manufacturer.
a) Function
Operate the trigger of the torch and check by means of the gas flow whether the magnetic
gas valve operates.
b) Leakage
Pressurize the system and verify there is no leak, for example, there is no pressure drop.
NOTE Flexible gas tubes and their connections can be sources of leaks.
6.5 Signal and control lamps
Signal or control lamps shall be checked for correct operation if possible.
Conformity shall be checked by VISUAL INSPECTION.
– 18 – IEC 60974-4:2025 © IEC 2025
7 Documentation
7.1 Test report
The test report shall include
a) identification of tested arc welding equipment,
b) date of testing,
c) supply voltage,
d) test results,
e) signature, identification of the test performing personnel and his organization,
f) identification of testing equipment.
REPAIR, shall include all the tests given in Table 1 and an indication shall
The test report, after
be made if a particular test has not been carried out.
An example of a test report is given in Annex B.
7.2 Labelling
A label shall be attached to the equipment to indicate that it has passed the test.
The label shall state the date of testing or recommended date for next inspection depending on
local regulation.
Annex A
(informative)
Checklist for the VISUAL INSPECTION
During VISUAL INSPECTION, the following listed items should be checked.
a) Torch/electrode holder, welding clamp
– missing or defective insulation,
– defective connections,
– defective, damaged switches,
– other damage.
b) Mains supply
– defective, damaged cable,
– deformed, faulty plug,
– broken or thermally damaged plug pins,
– ineffective cable anchorage,
– cables and plugs unsuitable for the intended use and performance.
c) WELDING CIRCUIT
– defective, damaged cable,
– deformed, faulty or thermally damaged coupler/sockets,
– ineffective cable anchorage,
– cables and couplers unsuitable for the intended use and performance.
d) Enclosure
– missing or damaged parts,
– unauthorized modifications,
– cooling openings blocked or missing air filters,
– signs of overload and improper use,
– missing or defective protective devices, for example, gas cylinder holder,
– missing or defective wheels, lifting means, holder, etc.,
– defective wire reel mounting means,
– conductive objects placed in the enclosure.
e) Controls and indicators
– defective switches, meters and lamps,
– defective pressure regulator or flowmeter,
– incorrect fuses accessible from outside the enclosure.
f) General condition
– excessive dust or pollution,
– cooling liquid circuit leaking or incorrect cooling liquid level,
– defective gas hoses and connections,
– poor legibility of markings and labelling,
– other damage or signs of improper use.
– 20 – IEC 60974-4:2025 © IEC 2025
Annex B
(informative)
Example of a test report after REPAIR
Test report
Company: Sample Ltd. Location: London Torchham WH15 B4
Equipment: ARC WELDING POWER SOURCE Type: Freefried S/N: 123456
Manufacturer: Freefried Electric Ltd. Protection class: I
Testing equipment: TEST DEVICE D6, Metaframe, measuring circuits as given in IEC 60974-4.
Mains voltage V 230
RMS
Test point: Limit Measured values
VISUAL INSPECTION --- OK
Protective conductor resistance ---
R 0,02 Ω
≤ 0,3 Ω
PE
Insulation resistance ---
– Supply circuit/ R
≥ 2,5 MΩ ≥ 20 MΩ
S-P
Protective circuit (500 V)
– WELDING CIRCUIT, control R ≥ 2,5 MΩ ≥ 20 MΩ
W, C-P
circuit/
Protective circuit (500 V)
– Supply circuit/ R
≥ 5 MΩ ≥ 20 MΩ
S,-W-C
WELDING CIRCUIT, control
circuit (500 V)
Protective conductor I 2 mA
≤ 10 mA
PE
RMS
current
TOUCH CURRENT in normal I ≤ 0,5 mA
T RMS
a
condition
0,04 mA
– Equipment with I N/A
≤ 0,05 I A
T
1max
reinforced protective
a
conductor
a
WELDING CIRCUIT TOUCH CURRENT
I 0,056 mA
≤ 10 mA
T
RMS
NO-LOAD VOLTAGE ---
U ≤ 68 V N/A
S
0 peak
With mark
N/A
U
≤ 113 V
peak
U 110 V
≤ 113 V
S
peak
Without mark
N/A
U
≤ 113 V
peak
Functional test --- ok
Test passed
Test performing personnel name --- Myself
Test performing personnel signature --- Me
Date --- 03-03-14
Remarks (result of VISUAL INSPECTION or functional test): None _______________________________________________
Testing company: Checkmates Limited ___________________________________________________________________
Address: London Weldshire WG3 A7 _____________________________________________________________________
REPAIR: replacement of broken main switch ________________________________________________________________
N/A: Not applicable to the REPAIR according to the investigator ______________________________________________
a
Additional measurements
Annex C
(informative)
Equipment not built in accordance with current IEC 60974-1
C.1 Welding equipment not built in accordance with IEC
...
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