SIST EN 60974-9:2010
Arc welding equipment - Part 9: Installation and use (IEC 60974-9:2010)
Arc welding equipment - Part 9: Installation and use (IEC 60974-9:2010)
This part of IEC 60974 is applicable to the installation and use of equipment for arc welding and allied processes designed in accordance with safety requirements of IEC 60974-1, IEC 60974-6 or equivalent. This part of IEC 60974 is applicable for the guidance of instructors, operators, welders, managers, and supervisors in the safe installation and use of equipment for arc welding and allied processes and the safe performance of welding and cutting operations. National and local regulations take precedence over this part of IEC 60974.
Lichtbogenschweißeinrichtungen - Teil 9: Errichten und Betreiben (IEC 60974-9:2010)
Matériel de soudage à l'arc - Partie 9: Installation et utilisation (CEI 60974-9:2010)
La CEI 60974-9:2010 est applicable à l'installation et à l'utilisation du matériel pour le soudage à l'arc et les procédés connexes conçus selon les exigences de sécurité de la CEI 60974-1, de la CEI 60974-6 ou équivalent. La présente partie de la CEI 60974 est applicable pour guider les instructeurs, les opérateurs, les soudeurs, les gestionnaires, et les superviseurs pour obtenir une installation et une utilisation sûres du matériel pour le soudage à l'arc et les techniques connexes et obtenir des performances sûres dans les opérations de soudage et de coupage. Cette première édition constitue une révision technique. Les modifications majeures par rapport à la CEI/TS 62081:1999 sont les suivantes:
- 4.3.3 Câbles de soudage: les dimensions sont maintenant recommandées;
- 5 Compatibilité électromagnétique (CEM): nouvel article;
- 6 Champs électromagnétiques (CEM): nouvel article;
- 7.3 Examen et maintenance de l'installation de soudage: on maintenant fait la différence entre examen périodique et examen quotidien.
Oprema za obločno varjenje - 9. del: Inštalacija in uporaba (IEC 60974-9:2010)
Ta del IEC 60974 se uporablja za inštalacijo in uporabo opreme za obločno varjenje in povezane postopke, ki so zasnovani v skladu z varnostnimi zahtevami IEC 60974-1, IEC 60974-6 ali enakovrednimi. Ta del IEC 60974 se uporablja kot navodila inštruktorjem, upravljalcem, varilcem, vodilnim delavcem in nadzornikom pri varni inštalaciji in uporabi opreme za obločno varjenje in povezanih postopkih, in pri varnem izvajanju operacij varjenja in rezanja. Nacionalni in lokalni predpisi imajo prednost pred tem delom IEC 60974.
General Information
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Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Lichtbogenschweißeinrichtungen - Teil 9: Errichten und Betreiben (IEC 60974-9:2010)Matériel de soudage à l'arc - Partie 9: Installation et utilisation (CEI 60974-9:2010)Arc welding equipment - Part 9: Installation and use (IEC 60974-9:2010)25.160.30Varilna opremaWelding equipmentICS:Ta slovenski standard je istoveten z:EN 60974-9:2010SIST EN 60974-9:2010en01-september-2010SIST EN 60974-9:2010SLOVENSKI
STANDARDSIST CLC/TS 62081:20031DGRPHãþD
SIST EN 60974-9:2010
EUROPEAN STANDARD EN 60974-9 NORME EUROPÉENNE
EUROPÄISCHE NORM March 2010
CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: Avenue Marnix 17, B - 1000 Brussels
© 2010 CENELEC -
All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 60974-9:2010 E
ICS 25.160.30 Supersedes CLC/TS 62081:2002
English version
Arc welding equipment -
Part 9: Installation and use (IEC 60974-9:2010)
Matériel de soudage à l'arc -
Partie 9: Installation et utilisation (CEI 60974-9:2010)
Lichtbogenschweißeinrichtungen -
Teil 9: Errichten und Betreiben (IEC 60974-9:2010)
This European Standard was approved by CENELEC on 2010-03-01. 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 Central Secretariat 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 Central Secretariat 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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom.
SIST EN 60974-9:2010
EN 60974-9:2010 - 2 -
Foreword The text of document 26/404/FDIS, future edition 1 of IEC 60974-9, prepared by IEC TC 26, Electric welding, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 60974-9 on 2010-03-01. This standard supersedes CLC/TS 62081:2002.
The following major differences with respect to CLC/TS 62081:2002 are to be noted: − 4.3.3 Welding cables: Now dimensions are recommended. − 5 Electromagnetic compatibility (EMC): this is completely new. − 6 Electromagnetic fields (EMF): this is completely new. − 7.3 Inspection and maintenance of the welding installation: There is now a differentiation between periodical and routine inspection. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent rights. The following dates were fixed: – latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement
(dop)
2010-12-01 – latest date by which the national standards conflicting
with the EN have to be withdrawn
(dow)
2013-03-01 Annex ZA has been added by CENELEC. __________ SIST EN 60974-9:2010
- 3 - EN 60974-9:2010 Endorsement notice The text of the International Standard IEC 60974-9:2010 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 60204-1 NOTE
Harmonized as EN 60204-1. IEC 60364-4-41 NOTE
Harmonized as HD 60364-4-41. IEC 60974-2 NOTE
Harmonized as EN 60974-2. IEC 60974-3 NOTE
Harmonized as EN 60974-3. IEC 60974-5:2007 NOTE
Harmonized as EN 60974-5:2008 (not modified). IEC 60974-7 NOTE
Harmonized as EN 60974-7. IEC 60974-8 NOTE
Harmonized as EN 60974-8. IEC 61008 series NOTE
Harmonized in EN 61008 series (partially modified). IEC 61009 series NOTE
Harmonized in EN 61009 series (partially modified). IEC 61140 NOTE
Harmonized as EN 61140. ISO 11611 NOTE
Harmonized as EN ISO 11611. __________
SIST EN 60974-9:2010
EN 60974-9:2010 - 4 - Annex ZA
(normative)
Normative references to international publications with their corresponding European publications
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
NOTE
When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD applies.
Publication Year Title EN/HD Year
IEC 60245-6 - Rubber insulated cables - Rated voltages up to and including 450/750 V -
Part 6: Arc welding electrode cables - -
IEC/TR 60755 - General requirements for residual current operated protective devices
- -
IEC 60974-1 2005 Arc welding equipment -
Part 1: Welding power sources EN 60974-1 2005
IEC 60974-4 - Arc welding equipment -
Part 4: In-service inspection and testing EN 60974-4 -
IEC 60974-6 - Arc welding equipment -
Part 6: Limited duty manual metal arc welding power sources EN 60974-6 -
IEC 60974-10 - Arc welding equipment -
Part 10: Electromagnetic compatibility (EMC) requirements EN 60974-10 -
IEC 60974-11 - Arc welding equipment -
Part 11: Electrode holders EN 60974-11 -
IEC 60974-12 - Arc welding equipment -
Part 12: Coupling devices for welding cables EN 60974-12 -
SIST EN 60974-9:2010
IEC 60974-9Edition 1.0 2010-01INTERNATIONAL STANDARD
Arc welding equipment –
Part 9: Installation and use
INTERNATIONAL ELECTROTECHNICAL COMMISSION UICS 25.160.30 PRICE CODEISBN 2-8318-1075-4
® Registered trademark of the International Electrotechnical Commission ® SIST EN 60974-9:2010
– 2 – 60974-9 © IEC:2010(E) CONTENTS FOREWORD.4 1 Scope.6 2 Normative references.6 3 Terms and definitions.6 4 Installation.8 4.1 General.8 4.2 Supply circuit.8 4.2.1 Selection of supply cables.8 4.2.2 Supply disconnecting device.8 4.2.3 Emergency stopping device.8 4.3 Welding circuit.9 4.3.1 Isolation from the input supply.9 4.3.2 Summation of no-load voltages.9 4.3.3 Welding cables.9 4.3.4 Connection between the welding power source and the workpiece.9 4.3.5 Earthing of the workpiece.10 4.3.6 Location of gas cylinders.11 5 Electromagnetic compatibility (EMC).11 5.1 General.11 5.2 Assessment of area.11 5.3 Methods of reducing emissions.11 5.3.1 Public supply system.11 5.3.2 Maintenance of arc welding equipment.12 5.3.3 Welding cables.12 5.3.4 Equipotential bonding.12 5.3.5 Earthing of the workpiece.12 5.3.6 Screening and shielding.12 6 Electromagnetic fields (EMF).12 7 Use.13 7.1 General requirements.13 7.2 Connection between several welding power sources.13 7.3 Inspection and maintenance of the welding installation.13 7.3.1 Periodical inspection.13 7.3.2 Routine inspection.13 7.4 Disconnection of welding power sources and/or welding circuits.14 7.5 Guards.14 7.6 Information for operators.14 7.7 Protective measures.14 7.7.1 Extraneous conductive parts in the welding area.14 7.7.2 Protection against electric shock.14 7.8 Isolation of the welding circuit from the workpiece and earth when not in use.14 7.9 Voltage between electrode holders or torches.15 7.10 Welding in an environment with increased hazard of electric shock.17 7.11 Use of shoulder slings.17 7.12 Welding at elevated positions.18 SIST EN 60974-9:2010
60974-9 © IEC:2010(E) – 3 – 7.13 Welding with suspended welding equipment.18 Annex A (informative)
Hazards associated with arc welding.19 Annex B (informative)
Voltage drops in the welding circuit.25 Bibliography.27
Figure 1 – Example of d.c. voltage between electrode holders or torches.15 Figure 2 – Example of a.c. voltage between electrode holders or torches – Single-phase supply from the same pair of lines of a three-phase mains supply.16 Figure 3 – Example of a.c. voltage between electrode holders or torches – Single-phase supply from different pairs of lines of a three-phase mains supply.16 Figure 4 – Example of a.c. voltage between electrode holders
connected between different lines of output.17 Figure A.1 – Steps for the control of welding fume.22 Figure A.2 – Steps of operation for work in confined spaces.24 Figure B.1 – Example of MIG/MAG equipment.25
Table 1 – Current ratings for copper welding cables.9 Table B.1 – Voltage drop in copper and aluminium welding cables
at normal and elevated temperatures.26
SIST EN 60974-9:2010
– 4 – 60974-9 © IEC:2010(E) INTERNATIONAL ELECTROTECHNICAL COMMISSION ____________
ARC WELDING EQUIPMENT –
Part 9: Installation and use
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 60974-9 has been prepared by IEC technical committee 26: Electric welding. This standard cancels and replaces IEC/TS 62081, published in 1999. This first edition constitutes a technical revision. The following major differences with respect to
IEC/TS 62081:1999 are to be noted: • 4.3.3 Welding cables: Now dimensions are recommended. • 5 Electromagnetic compatibility (EMC): this is completely new. • 6 Electromagnetic fields (EMF) : this is completely new. SIST EN 60974-9:2010
60974-9 © IEC:2010(E) – 5 – • 7.3 Inspection and maintenance of the welding installation: There is now a differentiation between periodical and routine inspection. The text of this part of IEC 60974 is based on the following documents: FDIS Report on voting 26/404/FDIS 26/405/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 60974 series, under the general title Arc welding equipment,
can be found on the IEC website. The committee has decided that the contents of this publication will remain unchanged until the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in the data related to the specific publication. At this date, the publication will be
• reconfirmed, • withdrawn, • replaced by a revised edition, or • amended. A bilingual version of this standard may be issued at a later date.
SIST EN 60974-9:2010
– 6 – 60974-9 © IEC:2010(E) ARC WELDING EQUIPMENT –
Part 9: Installation and use
1 Scope This part of IEC 60974 is applicable to the installation and use of equipment for arc welding and allied processes designed in accordance with safety requirements of IEC 60974-1, IEC 60974-6 or equivalent. This part of IEC 60974 is applicable for the guidance of instructors, operators, welders, managers, and supervisors in the safe installation and use of equipment for arc welding and allied processes and the safe performance of welding and cutting operations. National and local regulations take precedence over this part of IEC 60974. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60245-6, Rubber insulated cables – Rated voltages up to and including 450/750 V – Part 6: Arc welding electrode cables IEC/TR 60755, General requirements for residual current operated protective devices IEC 60974-1:2005, Arc welding equipment – Part 1: Welding power sources IEC 60974-4, Arc welding equipment – Part 4: In-service inspection and testing IEC 60974-6, Arc welding equipment – Part 6: Limited duty manual metal arc welding power sources IEC 60974-10, Arc welding equipment – Part 10: Electromagnetic compatibility (EMC) requirements IEC 60974-11, Arc welding equipment – Part 11: Electrode holders IEC 60974-12, Arc welding equipment – Part 12: Coupling devices for welding cables 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1
welding circuit circuit that includes all conductive material through which the welding current is intended to flow SIST EN 60974-9:2010
60974-9 © IEC:2010(E) – 7 – NOTE 1 In arc welding, the arc is a part of the welding circuit. NOTE 2 In certain arc welding processes, the arc may be established between two electrodes. In such a case, the workpiece is not necessarily a part of the welding circuit.
[IEC 60974-1:2005, 3.11] 3.2
extraneous conductive part conductive part not forming part of the electrical installation and liable to introduce an electric potential, generally the earth potential
NOTE Electrical installation includes the welding circuit. 3.3
workpiece metal piece or pieces on which welding or allied processes are performed 3.4
protective clothing and accessories protective clothing and accessories (e.g. gloves, hand shields, head masks and filter lenses) used in order to diminish electric shock risks and the effects of fume and spatter and to protect the skin and eyes against arc radiation 3.5
environments with increased hazard of electric shock environments where the hazard of electric shock by arc welding is increased in relation to normal arc welding conditions NOTE 1 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 risk of unavoidable or accidental contact by the operator; c) in wet, 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 Environments with increased hazard of electric shock are not meant to include places where electrically conductive parts in the near vicinity of the operator which can cause increased hazard have been insulated.
[IEC 60974-1:2005, 3.46] 3.6
industrial and professional use use intended only for experts or instructed persons
[IEC 60974-1:2005, 3.2] 3.7
expert competent person skilled person 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 Several years of practice in the relevant technical field may be taken into consideration in assessment of professional training. [IEC 60974-1:2005, 3.3] SIST EN 60974-9:2010
– 8 – 60974-9 © IEC:2010(E) 3.8
wire feeder equipment that delivers filler wire to the arc or weld zone which includes the wire-feed control and means to apply motion to the filler wire and may also include the filler wire supply [IEC 60974-5:2007, 3.11] 3.9
auxiliary power output circuit of a welding power source designed to provide electrical power to auxiliary equipment 4 Installation 4.1 General Welding equipment used in arc welding installations shall be intended for the purpose and shall be built in accordance with IEC 60974-1, IEC 60974-4, IEC 60974-6, IEC 60974-10, IEC 60974-11 and IEC 60974-12 (see Clause 2), as given on the rating plate. Electromagnetic compatibility (EMC) requirements shall be taken into consideration during installation, see Clause
5. The requirements of national and local regulations shall be taken into consideration during installation, including grounding or protective earth connections, fuses, supply disconnecting device, type of supply circuit, etc. Read the manufacturers’ instruction manual before installing the equipment. Full use shall be made of the technical information relevant to the welding equipment. Specific advice may be obtained from the welding equipment manufacturer if necessary. 4.2 Supply circuit 4.2.1 Selection of supply cables Supply cables for welding equipment and their overload protection, if not provided by the manufacturer, shall be selected in accordance with the information given in the manufacturers’ instruction manual. Supply cables shall be placed, so that they cannot be damaged in use. If that cannot be achieved, a sensitive residual current circuit breaker, capable of operating at a leakage current not exceeding 30 mA in accordance with IEC/TR 60755 shall be used to reduce the risk of electric shock. 4.2.2 Supply disconnecting device The installer shall ensure that a supply disconnecting device is fitted at the point of supply. NOTE A plug may be used as supply disconnecting device in accordance with national or local regulation. 4.2.3 Emergency stopping device When an emergency stopping device is required by national regulation (e.g. automatic welding equipment), it shall conform to relevant IEC standard. For welding in an environment with increased hazard of electric shock, see
7.10.
SIST EN 60974-9:2010
60974-9 © IEC:2010(E) – 9 – 4.3 Welding circuit 4.3.1 Isolation from the input supply The welding circuit and circuits electrically connected to the welding circuit shall be electrically isolated from the mains supply. Verification shall be carried out by an expert. 4.3.2 Summation of no-load voltages If more than one welding power source is in use at the same time, their no-load voltages can be cumulative and could create an increased hazard of electric shock. Welding power sources shall be installed so as to minimize this risk. Guidance is given in
7.9. NOTE 1 In the case of two welding transformers connected to the same lines, the resulting output voltage may be the sum of both no-load voltages. This can be avoided by using a suitable input or output connection (see
7.9). NOTE 2 Where more than one welding power source is installed, individual welding power sources with their separate controls and connections should be clearly identified to show which items belong to any one welding circuit. 4.3.3 Welding cables Welding cables shall comply with IEC 60245-6. Copper conductor welding cables shall be selected in accordance with duty cycle and national regulations or, when not existing, current rating given in Table 1. Where long cable runs are involved, it may be necessary to choose the cable size on the basis of voltage drop, see Annex B. Table 1 – Current ratings for copper welding cables Current ratings for specified duty cycle at an ambient temperature of 25 °Ca Nominal cross-sectional area 100 % 85 % 80 % 60 % 35 % 20 % 8 % mm2 A A A A A A A 10 100 100 100 101 106 118 158 16 135 136 136 139 150 174 243 25 180 182 183 190 213 254 366 35 225 229 231 243 279 338 497 50 285 293 296 316 371 457 681 70 355 367 373 403 482 602 908 95 430 448 456 498 606 765 1 164 120 500 524 534 587 721 917 1 404 150 580 610 622 689 853 1 090 1 676 185 665 702 717 797 995 1 277 1 971 a For higher ambient temperatures, a correction factor shall be applied:
0,96 (30 °C) ; 0,91 (35 °C) ; 0,87 (40 °C) ; 0,82 (45 °C).
4.3.4 Connection between the welding power source and the workpiece When the welding current does not flow entirely in the welding circuit, stray currents, which are components of the welding current, occur. These can cause damage and may be eliminated by the following means: SIST EN 60974-9:2010
– 10 – 60974-9 © IEC:2010(E) a) the electrical connection between the welding power source and the workpieces shall be made as direct as practicable by means of an insulated return cable having an adequate current carrying capacity; b) extraneous conductive parts, such as metal rails, pipes and frames shall not be used as part of the welding circuit, unless they constitute the workpiece itself; c) the return clamp shall be as near as practicable to the welding arc;
NOTE 1 When the return clamp is removed, it should be electrically isolated from parts connected to earth, e.g. metallic enclosures with protective earth connection (class I), metal floors, building services. d) the welding circuit shall not be earthed unless required by national or local regulations (see
4.3.5); e) connection of the return cable to the workpiece shall be ensured by the use of devices having suitable means for cable connection, a fastening system not liable to come loose accidentally, and good electrical contact. Magnetic devices only present a good electrical contact if the contact surfaces of the magnetic device and the contact area of the workpiece are sufficiently large, even, conductive and clean (e.g. free from rust and primer) and if the contact area of the workpiece is magnetic;
NOTE 2 If workpieces are on a welding bench or a work-handling device, the return cable may be connected to the bench or device. f) connection devices for non-stationary flexible welding cables in the welding circuit shall: 1) have an adequate covering of insulating material to prevent inadvertent contact with live parts, when connected, with the exception of the return clamp at the workpiece itself; 2) be suitable for the sizes of cables used and the welding current;
3) be effectively connected to the welding cables and in good electrical contact with them. Both the welding cable and the connection device shall be used within their specified current rating. The connection device shall not be fitted with a cable smaller in diameter than specified by the manufacturer of the connection device. When coupling devices are used, they shall comply with IEC 60974-12. 4.3.5 Earthing of the workpiece The welding circuit should not be earthed, since it can increase the risk of stray welding currents (see
4.3.3). Earthing of the welding circuit can also increase the area of metal through which a person in contact with the welding circuit (e.g. the welding electrode) could receive a shock. NOTE 1 There are workpieces which have an inherent connection to earth, e.g. steel structures, ships, pipelines etc. When these are welded, the possibility of stray currents is increased. NOTE 2 In some cases the workpiece may be in permanent contact with earth, e.g. with protection class I equipment which itself has protective conductors connected to earth. Such a workpiece is considere
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