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AS 1674.2—2007 (Incorporating Amendment No. 1)

Australian Standard®

Safety in welding and allied processes

Part 2: Electrical

AS

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This Australian Standard® was prepared by Committee EL-019, Electrical Welding Plant. It was approved on behalf of the Council of Standards Australia on 2 February 2007. This Standard was published on 16 April 2007.

The following are represented on Committee EL-019:

• Australian Chamber of Commerce and Industry • Australian Industry Group • Australian Manufacturing Workers Union • Electrical Regulatory Authorities Council • Welding Technology Institute of Australia

This Standard was issued in draft form for comment as DR 05498. Standards Australia wishes to acknowledge the participation of the expert individuals that contributed to the development of this Standard through their representation on the Committee and through the public comment period.

Keeping Standards up-to-date Australian Standards® are living documents that reflect progress in science, technology and systems. To maintain their currency, all Standards are periodically reviewed, and new editions are published. Between editions, amendments may be issued. Standards may also be withdrawn. It is important that readers assure themselves they are using a current Standard, which should include any amendments that may have been published since the Standard was published. Detailed information about Australian Standards, drafts, amendments and new projects can be found by visiting www.standards.org.au Standards Australia welcomes suggestions for improvements, and encourages readers to notify us immediately of any apparent inaccuracies or ambiguities. Contact us via email at [email protected], or write to Standards Australia, GPO Box 476, Sydney, NSW 2001.

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AS 1674.2—2007 (Incorporating Amendment No. 1)

Australian Standard®


Part 2: Electrical

Originated in part as AS CC5—1947 and MP 17—1965. AS CC5—1965 and MP 17—1965 revised, amalgamated and redesignated as AS 2745—1984. AS 2745—1984 revised and redesignated as AS 1674.2—1990. Third edition 2007. Reissued incorporating Amendment No. 1 (February 2011).

COPYRIGHT

© Standards Australia Limited

All rights are reserved. No part of this work may be reproduced or copied in any form or by

any means, electronic or mechanical, including photocopying, without the written

permission of the publisher, unless otherwise permitted under the Copyright Act 1968.

Published by SAI Global Limited under licence from Standards Australia Limited, GPO Box

476, Sydney, NSW 2001, Australia

ISBN 0 7337 8142 X

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AS 1674.2—2007 2

PREFACE

This Standard was prepared by the Standards Australia Committee EL-019, Electrical

Welding Plant, to supersede AS 1674.2—2003.

This Standard incorporates Amendment No. 1 (February 2011). The changes required by

the Amendment are indicated in the text by a marginal bar and amendment number against

the clause, note, table, figure or part thereof affected.

The objective of this Standard is to provide a significant improvement in the safety of

welding in hazardous environments, where, in recent years, there have been a number of

deaths by electrocution.

The major changes from the 2003 edition of this Standard are as follows:

(a) Clarifications have been made that control measures are required to remove water

from category C environments.

(b) The scope has been modified to ensure that high ripple current d.c. welding power

sources are to be treated as a.c. power sources and to specifically exclude welding

underwater.

(c) A Table has been added to Section 5 detailing minimum insulation resistances for

routine inspection and testing of welding power sources.

The term ‘informative’ has been used in this Standard to define the application of the

appendix to which is applies. An ‘informative’ appendix is only for information and

guidance.

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3 AS 1674.2—2007

CONTENTS

Page

SECTION 1 SCOPE AND GENERAL

1.1 SCOPE ........................................................................................................................ 4

1.2 REFERENCED DOCUMENTS .................................................................................. 4

1.3 DEFINITIONS ............................................................................................................ 5

SECTION 2 RISK ASSESSMENT AND PERSONAL SAFETY

2.1 GENERAL .................................................................................................................. 9

2.2 CLASSIFICATION OF WELDING ENVIRONMENT............................................... 9

2.3 CONTROL MEASURES............................................................................................. 9

2.4 PARTICULAR HAZARDS WITH PLASMA-ARC PROCESSES ........................... 11

SECTION 3 EQUIPMENT

3.1 HELMETS, HANDSHIELDS, GOGGLES, FACE MASKS AND GLOVES............ 12

3.2 POWER SOURCES................................................................................................... 12

3.3 ANCILLARIES ......................................................................................................... 16

SECTION 4 ELECTRICAL CONNECTIONS

4.1 CONNECTION TO ELECTRICITY SUPPLY.......................................................... 17

4.2 WELDING CIRCUIT CONNECTIONS.................................................................... 17

4.3 EARTHING............................................................................................................... 19

4.4 CONNECTING MULTIPLE POWER SOURCES TO A COMMON WORKPIECE 19

SECTION 5 INSPECTION AND MAINTENANCE

5.1 POWER SOURCE..................................................................................................... 24

5.2 ACCESSORIES......................................................................................................... 25

APPENDICES

A TYPICAL ELECTRICAL HAZARDS ...................................................................... 26

B FATAL ELECTRICAL ACCIDENTS....................................................................... 34

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AS 1674.2—2007 4

© Standards Australia www.standards.org.au

STANDARDS AUSTRALIA

Australian Standard


Part 2: Electrical

S E C T I O N 1 S C O P E A N D G E N E R A L

1.1 SCOPE

This Standard sets out safety requirements for arc welding and allied processes, to reduce

the possibility of electric shock and minimize associated hazards. It includes requirements

for cable connections for alternating and direct current power sources, as well as

requirements for hazard-reducing devices and other ancillary equipment. It also describes

practices and safeguards that should be adopted by welders and provides examples of

situations that present an increased risk of electric shock.

For the purposes of this Standard the term ‘direct current’ (d.c.) is considered to be a direct

current with a sinusoidal ripple content of not more than 10% r.m.s. Any d.c. power source

with a sinusoidal ripple content of more than 10% shall be considered as an a.c. power

source (eg. a single phase unfiltered full wave rectified d.c. power source has a nominal

sinusoidal ripple content of 48%).

This Standard does not cover electrical safety requirements when welding is carried out

underwater.

NOTES:

1 Other aspects of welding safety are covered in other Standards.

2 Typical electrical hazards are described in Appendix A.

3 Some fatal electrical accidents are reported in Appendix B.

1.2 REFERENCED DOCUMENTS

The following documents are referred to in this Standard:

AS

1674 Safety in welding and allied processes

1674.1 Part 1: Fire precautions

2812 Welding, brazing and cutting of metals—Glossary of terms

60529 Degrees of protection provided by enclosures (IP Code)

60974 Arc welding equipment

60974.1 Part 1: Welding power sources (IEC 60974-1, Ed.2.2 (2000) MOD)

60974.6 Part 6: Limited duty portable arc welding and allied process power

sources (IEC 60974-6, Ed. 1.0 (2003) MOD)

60974.11 Part 11: Electrode holders (IEC 60974-11, Ed.2.0 (2004))

AS/NZS

1336 Recommended practices for occupational eye protection

1337 Eye protectors for industrial applications

1338 Filters for eye protectors

1338.1 Part 1: Filters for protection against radiation generated in welding and

allied operations

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5 AS 1674.2—2007

www.standards.org.au © Standards Australia

AS/NZS

1995 Welding cables

2161 Occupational protective gloves

2161.4 Part 4: Protection against thermal risks (heat and fire)

2865 Safe working in a confined space

3000 Electrical installations (known as the Australian/New Zealand Wiring Rules)

3100 Approval and test specification—General requirements for electrical

equipment

60479 Effects of current on human beings and livestock

60479.1 Part 1: General aspects

IEC

60974 Arc welding equipment

60974-2 Part 2: Liquid cooling systems

60974-5 Part 5: Wire feeders

60974-7 Part 7: Torches

60974-12 Part 12: Coupling devices for welding cables

WTIA [The Welding Technology Institute of Australia]

Tech. Note 7 Technical Note No.7: Health and safety in welding

Tech. Note 22 Technical Note No.22: Welding electrical safety

1.3 DEFINITIONS

For the purpose of this Standard, the definitions given in AS 2812 and those below apply.

NOTE: Diagrams for the purpose of illustrating some definitions relating to arc welding

installations are given in Figure 1.3.

1.3.1 Allied process

An electric arc process that is not used for joining, such as air arc gouging, air arc cutting,

metal arc cutting, arc spraying and plasma spraying.

1.3.2 Authorized

1.3.2.1 Authorized inspector

A person authorized by an authority administering acts of Parliament or regulations under

such acts or, in the absence of such acts and regulations, any person appointed by the Fire

and Accident Underwriters’ Association or the electricity supply or other authority, to

inspect installations.

1.3.2.2 Authorized person

A person in charge of a premises or a licensed electrical contractor, electrician or other

person appointed or selected by the person in charge of a premises, to perform certain

duties.

1.3.3 Conductor

1.3.3.1 Electrode conductor

Fixed wiring between a machine electrode or work terminal and the corresponding output

terminal.

1.3.3.2 Work (or return) conductor

Fixed wiring between a machine work or return terminal and the corresponding output

terminal.

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AS 1674.2—2007 6


1.3.4 Control lead

A lead that connects the power source to ancillary devices, for control or regulating

purposes, but is not part of the welding circuit.

1.3.5 Distribution box

A multi-operator arrangement of connections, sockets or terminals that is enclosed in a box

or covered space, dividing a welding circuit into two or more branches that are suitable for

use by two or more welders.

1.3.6 Environment

1.3.6.1 Category A environment (see Clause 2.2(a))

An environment where—

(a) the risk of an electric shock or electrocution by arc welding is low;

(b) normal work practice is used; and

(c) it is not possible for a welder or any other worker to be in contact with the workpiece,

in the event of being in contact with a live part of the welding circuit.

1.3.6.2 Category B environment (see Clause 2.2(b))

An environment where there is a significant risk of the welder contacting the workpiece or

other parts of the welding circuit.

NOTE: Such an environment may be found where the ambient temperature is less than 32°C

and—

(a) freedom from movement is restricted, so that an operator is forced to perform welding

in a cramped position (e.g., kneeling, sitting, lying), with physical contact with

conductive parts (e.g., the workpiece); or

(b) there is a high risk of accidental or unavoidable contact by the operator with

conductive elements, which may or may not be in a confined space as defined in

AS/NZS 2865.

1.3.6.3 Category C environment (see Clause 2.2(c))

An environment where the risk of an electric shock or electrocution by arc welding is

greatly increased due to low body impedance of the welder and a significant risk of the

welder contacting the workpiece or other parts of the welding circuit.

NOTE: Low body impedance is likely in the presence of water, moisture or heat, particularly

where the ambient temperature is above 32°C. In wet, moist or hot locations, humidity or

perspiration considerably reduces the skin resistance of human bodies and the insulating

properties of personal protective equipment accessories and clothing.

1.3.7 FCAW

Flux-cored arc welding.

1.3.8 GMAW

Gas metal-arc welding.

1.3.9 GTAW

Gas tungsten-arc welding.

1.3.10 Hazard-reducing device (HRD)

A device designed to reduce the hazard of electric shocks from a welding circuit.

1.3.11 Licensed electrical worker

A person who holds an appropriate licence or approval to carry out electrical work in

accordance with AS/NZS 3000.

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7 AS 1674.2—2007


1.3.12 Mains installation (electrical)

Wiring systems, switchgear, control gear, accessories, appliances, luminaires and fittings

associated with wiring situated on any premises to which electricity is supplied or is to be

supplied through any one service to a consumer.

1.3.13 MMAW

Manual metal-arc welding.

1.3.14 Observer

A person whose sole responsibility is to monitor the welder(s) activity, and who is capable

of responding appropriately in an emergency.

1.3.15 Open-circuit voltage (OCV) or no-load voltage

The voltage between output terminals of a power source, while it is switched on, but not

delivering any current.

1.3.16 Output lead (or cable)

1.3.16.1 Electrode lead (or cable)

A lead between an electrode holder or torch and an electrode output terminal of an electrode

conductor, distribution box, choke or power source.

1.3.16.2 Work (or return) lead (or cable)

A lead between work and a return or work output terminal of a return conductor,

distribution box or power source.

NOTE: The term ‘earth lead’ is often incorrectly used to refer to a return lead or a work lead.

1.3.17 Power source (also known as welding machine)

A device that supplies welding current and output characteristics that are suitable for arc

welding or allied processes.

1.3.18 SAW

Submerged arc welding.

1.3.19 Shall

Indicates that a statement is mandatory.

1.3.20 Should

Indicates a recommendation.

1.3.21 Terminal

1.3.21.1 Power source terminal

A terminal of a welding or cutting power source, for the connection of conductors or leads

of a welding circuit (see Figure 1.1).

1.3.21.2 Output terminal

A terminal in a welding circuit to which an output lead is connected.

1.3.22 Voltage-reducing device (VRD)

A type of hazard-reducing device (either internally or externally fitted to a welding power

source) that is designed to automatically reduce the open-circuit voltage to a safer level.

1.3.23 Welder

A person who performs welding (including tack welding) or cutting operations.

NOTE: The term ‘welder’ is often used incorrectly to refer to a welding power source.

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AS 1674.2—2007 8


1.3.24 Welding

The making of a joint between parts, by means of heat or pressure or both, in such a way

that there is continuity in the nature of the material of the parts.

NOTE: A filler material may or may not be used.

1.3.25 Welding circuit (also known as output circuit)

A circuit that includes the conductive material through which a welding current is intended

to flow.

NOTES:

1 An arc is part of a welding circuit.

2 In certain welding processes, an arc may be established between two electrodes. In such a

case, the workpiece is not necessarily part of the welding circuit.

1.3.26 Welding current

Current delivered by a power source during welding.

NOTE: These diagrams are for purposes of illustration and do not embrace all the possible combination of

circumstances.

FIGURE 1.3 ILLUSTRATION OF SOME ARC WELDING TERMS

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9 AS 1674.2—2007


S E C T I O N 2 R I S K A S S E S S M E N T A N D

P E R S O N A L S A F E T Y

2.1 GENERAL

Parts of welding circuits, including workpieces and current return paths, have to be

considered electrically alive. Consequently, welders shall follow the precautions and

requirements in this Section, to minimize the risk of current passing through their body.

Before use, equipment shall be examined for soundness and proper maintenance in

accordance with Section 5.

2.2 CLASSIFICATION OF WELDING ENVIRONMENT

Before welding commences, the work area shall be assessed and the welding environment

classified for risk of electric shock in accordance with Clause 1.3.6. Also the following

apply:

(a) Category A environment (see Clause 1.3.6.1) In Category A environments,

considerable effort is required to insulate the welder and others from the workpiece,

such as bench-top welding where the workpiece is small and there is a low risk of the

welder becoming part of the circuit; or where both the welder and any assistants are

prevented from being in contact with conductive parts. For repetitive operations, such

an environment is usually limited to carefully designed workstations, as well as

welder training and welding procedure qualification test bays.

NOTE: AS 60974.1 and AS 60974.6 classify a Category A environment as ‘an environment

without increased hazard of electric shock’.

(b) Category B environment (see Clause 1.3.6.2) Category B environments include

general fabrication activities, large workpieces, steel building structures, inside

pressure vessels, processing tanks, storage tanks, conductive confined spaces and

onboard ships.

NOTES:

1 AS 60974.1 and AS 60974.6 classify Category B environments as ‘environment with

increased hazard of electric shock’.

2 When the weather is hot, when high preheat temperature is employed or when the vessel

is exposed to the sun, many Category B environments become Category C environments.

(c) Category C environment (see Clause 1.3.6.3) Category C environments include, but

are not limited to, coffer dams, trenches, underground mines, in rain, partially

submerged areas, splash zones (see also Appendix B).

NOTE: It may be possible to derate Category B and Category C environments, where

effective control measures are taken to reduce or eliminate the risk (e.g., airconditioning,

special insulating clothing).

2.3 CONTROL MEASURES

2.3.1 Category A environments

For welding in Category A environments (defined by Clause 1.3.6.1), Clause 2.2(a) and the

following apply:

(a) The electrode and workpiece shall be regarded as electrically live.

NOTE: The welder should take care to avoid contact with them.

(b) Welding gloves shall be sound, dry and used on both hands while welding or

changing electrodes.

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AS 1674.2—2007 10


(c) Welders should wear appropriate dry fireproof clothing that covers the legs and arms,

and footwear should be rubber soled and not have bare steel toecaps.

(d) Leather cushions, wooden duckboards or other means shall be used to insulate the

welder from damp concrete floors and any exposed parts of the workpiece.

(e) Leads and equipment shall be inspected for damage. Damaged equipment and leads

shall not be used, but removed from service for repair or discarded.

NOTE: A system of tagging for defective equipment is recommended.

(f) While tacking two pieces together, the arc shall be struck on the piece connected to

the return lead.

NOTE: Trying to tack weld on an unconnected piece will expose any person holding a piece

not connected to the return lead to the risk of electric shock.

(g) The work area shall be kept tidy and free from tangled leads, discarded cut-offs and

electrode stubs.

(h) The electrode holder or gun shall not be placed on the workpiece, where it may short

circuit.

NOTE: An insulated container should be provided.

(i) The power shall be turned off and MMAW electrodes and stub ends removed from the

electrode holder, before the welder leaves the work area and whenever the leads have

to be moved.

NOTE: Further detailed advice may be obtained from WTIA Tech. Notes 7 and 22.

2.3.2 Category B environments

While welding in Category B environments (see Clause 1.3.6.2), Clauses 2.2(b) and 2.3.1

and the following apply:

(a) Where practicable, care shall be taken to convert to a Category A environment.

NOTE: Insulating cushions, sheets, blankets, duckboards and other suitable protection should

be used to insulate the welder, if practical.

(b) The open-circuit voltage in a Category B environment shall not exceed 113 V d.c

peak or 68 V a.c. peak and 48 V a.c. r.m.s.

The open circuit voltage shall be measured, to ensure it is within the specified limits.

If necessary, the power source shall be fitted with a hazard-reduction device

complying with Clause 3.2.7, in order to comply with this requirement.

NOTE: Power sources complying with AS 60974.1 should have been marked with the letter S

in a square on the compliance plate, to indicate its safety in such an environment (see

Table 3.2.2). Many a.c. MMAW power sources, particularly older machines, do not meet this

requirement and should not be used in a Category B environment.

(c) Whenever the welder works without an observer, the open circuit voltage shall not

exceed 35 V d.c. peak or 35 V a.c. peak and 25 V a.c. r.m.s. (i.e., the same as in Item

2.3.3(e) for a Category C environment).

NOTE: The use of a HRD may be required.

(d) Where the environment is a confined space, the provisions of AS/NZS 2865 shall also

apply, which specifies requirements for access to the space, egress from the space in

an emergency, avoiding asphyxiation and avoiding entanglement or entrapment.

Where access to the space is restricted, an observer, as described in Clause 1.3.14,

shall be required.

NOTES:

1 These control measures should be included in the hot work permit described in AS 1674.1.

2 Further detailed advice may be obtained from WTIA Tech. Notes 7 and 22.

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11 AS 1674.2—2007


2.3.3 Category C environments

For welding in Category C environments (defined by Clause 1.3.6.3), Clauses 2.2(c) 2.3.2

and the following apply:

(a) Where it is determined that the welder or welding equipment can become wet from

rain, splashing, partial submersion or other external sources, then adequate control

measures shall be implemented before welding commences.

(b) Every effort shall be made to make the environment as cool as possible to minimize

perspiration.

(c) An observer shall be appointed to monitor the welder. The observer or a third person

working close by shall be trained in rescue and emergency procedures. The observer

may monitor more than one welder, provided that the welders being monitored can be

observed at the same time.

(d) Maintenance of welding equipment shall not be undertaken in this environment.

(e) The voltage between the electrode holder and the workpiece while an arc is not

present shall not exceed 35 V d.c. peak or 35 V a.c. peak and 25 V a.c. r.m.s.

NOTES:

1 The use of covers to protect from water exposure (e.g., rain or a dripping roof),

air-conditioning and frequent changes of clothing (particularly cotton glove liners) should

minimize the risk.

2 Most equipment for GMAW, FCAW and GTAW complies with this requirement, because the

current is switched with a trigger switch.

3 For MMAW or similar processes, such as carbon-arc gouging, the power source may require

an additional hazard-reducing device.

4 Further detailed advice may be obtained from WTIA Tech. Notes 7 and 22.

2.4 PARTICULAR HAZARDS WITH PLASMA-ARC PROCESSES

Plasma-arc processes can produce fumes, gases, noise, radiation and heat, and explosion

when cutting aluminium, which can present greater hazards than typical arc welding

processes.

Plasma-arc cutting equipment presents a greater risk of electric shock than arc welding

equipment, due to the higher voltages.

NOTE: Reference should be made to the supplier’s recommendations for guidance on protection

from these potential hazards.

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AS 1674.2—2007 12


S E C T I O N 3 E Q U I P M E N T

3.1 HELMETS, HANDSHIELDS, GOGGLES, FACE MASKS AND GLOVES

Helmets, hand shields, goggles and face masks shall be designed so that no

injury to the wearer can arise through conduction of electricity through the

material, and any metal parts which might touch the head or face shall be

electrically insulated.

NOTE: Helmets, hand shields, goggles and facemasks should comply with AS/NZS 1336,

AS/NZS 1337 or AS/NZS 1338.1. Gloves should comply with AS/NZS 2161.4.

3.2 POWER SOURCES

3.2.1 General

In addition to the requirements specified herein, power sources shall comply with the

relevant requirements of AS 60974.1, AS/NZS 3100 and AS 60974.6.

3.2.2 Degree of protection

The power source shall have a degree of protection that suits the environment in which it is

to be used.

NOTES:

1 Box 22 on the rating plate of power sources should show the degree of protection in

accordance with AS 60974.1.

2 Table 3.2.2 shows a typical rating plate.

3 Power sources rated with an IP21 degree of protection, as designated by AS 60529, are for

indoor use only.

4 Power sources rated with a minimum of IP23 degree of protection, as designated by

AS 60529, may be used outdoors.

5 The design and testing of power sources for use in Category B and Category C environments

should be agreed between the manufacturer and the purchaser. Examples of such conditions

include high humidity, unusually corrosive fumes, steam, excessive oil vapour, abnormal

vibration, abnormal shock, excessive dust, severe weather conditions, unusual coastal

conditions, shipboard conditions, vermin infestation and atmospheres conducive to the growth

of fungus.

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13 AS 1674.2—2007


TABLE 3.2.2

BOX NUMBERS

3.2.3 Terminals

Output terminals on the welding power source shall be enclosed, covered or otherwise

protected, to prevent inadvertent contact. Covers shall be of a robust design, with adequate

mechanical properties, and effectively maintained.

Terminals remote from the power source shall be marked in accordance with the relevant

requirements of AS 60974.1.

The words EARTH or GROUND shall not be marked on the output circuit. The welding

circuit cable shall not be coloured or tagged green and/or yellow.

3.2.4 Internal insulation

Power sources designated Class I Protection, as designated by AS/NZS 3000, shall be

connected to the power supply earth system.

Power sources designated Class II protection, as designated by AS/NZS 3000, do not

require connection to the power supply earth system.

NOTE: Where a power source has a Class II Protection, Box 23 of its rating plate will contain a

symbol consisting of two concentric squares.

3.2.5 Control

The power source shall be controlled by a switch that is incorporated in its primary circuit.

The switch shall have a designated OFF position and be mounted on or adjacent to the

power source framework. Where the power source is connected to the supply by means of a

power supply cord and plug, any switch mounted on the power source shall open all live

conductors, including the neutral.

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AS 1674.2—2007 14


3.2.6 Maximum open-circuit voltage

Except as provided for in Clauses 3.2.7 and 3.2.8, the maximum open-circuit voltage shall

not exceed the values specified in Table 3.2.6.

TABLE 3.2.6

MAXIMUM PERMITTED OPEN CIRCUIT VOLTAGE

Working conditions Maximum permitted open circuit voltage

Category A environment (Clause 2.2(a)) d.c. 113 V peak, or

a.c. 113 V peak and 80 V rms

Category B environment (Clauses 1.3.6.2 and 2.2(b)) d.c. 113 V peak, or


Category C environment (Clauses 1.3.6.3 and 2.2(c)) d.c. 35 V peak, or


Mechanically held torches with increased protection

for the operator

d.c. 141 V peak, or


Plasma cutting d.c. 500 V peak

NOTES:

1 Each power source, complying with AS 60974.1, that is suitable for a Category B environment should be

marked with a symbol comprising the letter ‘S’ in a square box. This symbol can be found in Box 7 of the

rating plate or sometimes on the front panel.

2 MMAW power sources to old Standards may supply excessively high a.c. voltages for Category B and

Category C environments. It is necessary to measure the open-circuit voltage to determine suitability and,

if necessary, fit a hazard-reduction device.

3 Power sources to be used in Category C environments may require a hazard-reducing device (see

Clauses 2.3.3 and 3.2.7).

Conformity shall be checked by measurement and by analysis of the circuit or by the failure

simulation or both.

Measurement shall be as follows:

(a) RMS values A true r.m.s meter is used with a resistance of the external welding

circuit of 5 kΩ with a maximum tolerance of ±5%.

(b) Peak values To obtain reproducible measurements of peak values, omitting impulses

which are not dangerous, a circuit is used as shown in Figure 3.2.6.

1 = Diode 1N4007 or similar

FIGURE 3.2.6 MEASUREMENT OF PEAK VALUES

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15 AS 1674.2—2007


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%.

During the measurement, the potentiometer is varied from 0 Ω to 5 kΩ in order to obtain

the highest peak value of the voltage measured with these loads of 200 Ω to 5.2 kΩ. This

measurement is repeated with the two connections to the measuring apparatus reversed.

3.2.7 Hazard-reducing devices

3.2.7.1 General

Hazard-reducing devices shall reduce electrical-shock hazards originating from no-load

voltages that exceed the values in Table 3.2.6.

The hazard reducing devices shall comply with the relevant requirements of AS 60974.1.

3.2.7.2 Voltage-reducing devices

The voltage reducing devices shall comply with the relevant requirements of AS 60974.1.

3.2.7.3 Hand-piece trigger switches

Where a hand-piece trigger switch is used as a hazard-reducing device⎯

(a) the voltage of its control circuit shall be not more than d.c. 35 V peak or a.c. 25 V

rms; and

(b) its switching mechanism shall⎯

(i) return to the OFF position, immediately the welder releases pressure on the

switch;

(ii) be easy to hold in the closed position, enabling the welder to carry out normal

welding operations, without muscle strain;

(iii) for MMAW and carbon-arc gouging have a two-stage operation to move to the

ON position, so that there is a low probability of accidental closure of the

switch during any hazardous operations (for example, changing electrodes); and

(iv) automatically latch in the OFF position, on release of pressure by the welder.

3.2.7.4 Indication of satisfactory operation of voltage-reducing devices

Each voltage-reducing device shall be provided with a reliable device that indicates that it

is operating satisfactorily. Where a lamp is used, it shall light when the voltage has been

reduced.

3.2.8 Ancillary devices

The welding power source cabinet may contain additional equipment, which may be

separate devices, such as a high-frequency arc-initiating device, a smoke removal device, a

wire feeder or a water cooler. If these devices are used, they should be made to appropriate

Standards, such as the IEC 60974 series of Standards.

Any additional equipment shall be connected to the power source in accordance with the

manufacturer’s recommendations. They shall either have their own isolation switches or be

isolated by the power source switch.

Users should be made aware that high-frequency arc-starting devices deliver up to 6500 V

at a current up to 100 mA, which is imposed over the welding current. It can give a severe

and painful electric shock. It may cause damage to electronic devices, such as heart

pacemakers, computers, electrical meters in the vicinity, even if they are not directly

connected to the same power supply.

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AS 1674.2—2007 16


Where it is necessary to earth any conductor of a high-frequency circuit, the earthing

connection shall be made to an earthing electrode driven into the ground and not under any

circumstances in contact with water or gas pipes or a building structure. The earthing

conductor to an earthing electrode shall have a cross-sectional area of not less than

2.5 mm2, be of stranded copper and be insulated with not less than 250 V grade insulation.

The earthing electrode and its connections shall be effectively shielded from personal

contact. (See also Figure 3.2.8 and AS/NZS 3000).

Any power source fitted with high-frequency arc-initiating equipment shall carry a warning

in a prominent position stating the following:

HIGH-FREQUENCY EQUIPMENT IS INSTALLED

VOLTAGES UP TO 6500 V MAY BE PRESENT WITHIN THE CABINET

DISCONNECT FROM POWER SUPPLY BEFORE REMOVING COVERS

FIGURE 3.2.8 INTERLOCK BETWEEN POWER SOURCE AND HIGH-FREQUENCY

ARC-INITIATING EQUIPMENT

3.3 ANCILLARIES

3.3.1 Electrode holders for MMAW

Electrode holders used for MMAW shall comply with AS 60974.11.

Where welding is carried out in a Category B or Category C environment or a position

where the welder may be injured by a fall, the electrode holder shall be a Type A as

specified in AS 60974.11.

Electrode holders shall have sound and crack-free insulation.

3.3.2 Plasma torches

Plasma torches shall comply with the relevant requirements of AS 60974.1.

3.3.3 Wire feeders

Whenever a welding circuit is energized, the wire feed mechanism, the wire path and the

welding wire are at electrode potential; thus, electric shock may result from contact with

any part.

Should welding wire short internally to the workpiece during welding, the welding wire will

become overheated and severe burns may follow inadvertent contact.

Covers should not be removed, as control voltages up to 115 V a.c. may be present.

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17 AS 1674.2—2007


S E C T I O N 4 E L E C T R I C A L C O N N E C T I O N S

4.1 CONNECTION TO ELECTRICITY SUPPLY

Power sources shall be connected to the electricity supply—

(a) via an approved supply flexible cord with plug and socket; or

(b) by a licensed electrical worker, if the power source is permanently connected to the

supply.

Power supply cords should be kept as short as possible.

Electrical wiring connecting a power source to an electricity supply, wiring connecting a

frame of a power source to earth and any permanent wiring connected to terminals to which

output leads are connected shall comply with the relevant requirements of AS/NZS 3000.

4.2 WELDING CIRCUIT CONNECTIONS

4.2.1 General

The connection of output leads is the responsibility of the welder. The power shall be

switched off when making such connections.

4.2.2 Welding leads

The following apply to welding leads:

(a) Welding leads shall conform to AS/NZS 1995.

(b) Welding leads should be kept as short as practicable.

(c) Welding leads shall be insulated and the insulation shall be in good repair. Where

high-frequency or similar devices are used, the insulation of the welding leads shall

be suitable for the high voltage.

(d) Welding leads longer than 9 m should not be used, unless the voltage drop of the

current used does not exceed the values in Clause 4.2.3.

(e) The nominal cross-sectional area of welding lead conductors needs to be increased as

the length is increased to compensate for cable voltage drop (see Clause 4.2.3).

NOTE: AS/NZS 1995 and WTIA Tech. Note 22 give guidance on the method of calculating

voltage drop and selection of an appropriate welding lead cross-section.

(f) Welding leads shall be fitted with appropriate terminals for connection to the

remainder of the welding circuit. The connection joint shall be clean and tight to

provide electrical continuity.

(g) Terminals and connections shall be fitted to welding leads by a competent person.

NOTE: It is highly recommended that the person’s competence for this task is assessed by a

licensed electrician. If the cables operate at 50 V a.c. or higher, the relevant State legislation

may require that this work be undertaken by a licensed electrician.

4.2.3 Voltage drop

The voltage drop in the leads and conductors comprising a welding circuit, with the

exception of an MMAW electrode lead attached to the electrode holder, should not exceed

1 V for each 7.6 m of cable, while carrying the rated-output current of the power source to

which they are connected.

The overall voltage drop of the conductors, leads and connections comprising a welding

circuit, while carrying output current, but excluding separately mounted current-limiting

devices, should not exceed 10% of the voltage at the power source terminals.

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AS 1674.2—2007 18


4.2.4 Electrode leads for MMAW

Electrode leads for MMAW may consist of two or more sections, to provide for quick

disconnection in case of emergency. The first section should have the electrode holder

connected to one end and a suitable insulated plug connected to the other end. The length of

this lead should not exceed 9 m. The second section should have a terminal at one end for

connection to the welding terminal and a corresponding insulated socket at the other end.

The length of this lead should be kept as short as possible, in order to avoid voltage drop

and the risk of cable damage.

4.2.5 Permanently installed welding circuit wiring

In most cases, the welding circuit is connected by flexible leads, which are exposed and

constantly moved. Any welding circuit that is permanently fixed (that is, using cabling in

ducts, cable trays or rigid electrical conductors) shall be designed and fitted by a licensed

electrical worker in accordance with AS/NZS 3000.

4.2.6 Work lead and work conductor

The workpiece shall be soundly connected to the welding power source by an insulated

cable complying with Clause 4.2.2, or by permanently installed wiring complying with

Clause 4.2.5.

Both the work lead and the work conductor should be kept clear of conducting materials,

such as earth and metallic structures.

The work lead shall be soundly connected to the workpiece, as close to the welding as

possible. The current should not be routed through uninsulated conductors, such as the

workpiece, the bench or bare metal strips. It shall never be routed through gas or water

pipes. The work lead may carry the current from multiple power sources, in which case its

capacity shall be determined by a competent electrician, having in mind the duty cycle of

the welding process.

NOTE: Failure to connect the work lead properly will lead to stray current problems, which are

discussed in Paragraph A6, Appendix A.

The current-carrying capacity of the work lead and work conductor shall be not less than

that of the electrode lead and electrode conductor.

4.2.7 Welding circuit connections

The welder is normally responsible for connecting the welding circuit, except for the fitting

of permanently fixed parts of the circuit and the fitting of terminals to leads, which shall be

as detailed in Clauses 4.2.2 and 4.2.5.

The power source shall be switched off or otherwise isolated from the supply, before

making any connections to it.

Water-cooled torches shall not be connected to water mains. An isolated water circulation

system shall be used.

4.2.8 Confined spaces

Where welding is performed in a confined space as defined by AS/NZS 2865, provision

shall be made in close proximity to the observer, to allow the welding circuit to be quickly

broken. This shall be by one of the following methods, in order of priority:

(a) Switching off primary power to the welding machine either at the supply outlet or on

the welding machine.

(b) A whole current switch that breaks the circuit when activated (for example, a stop

button) in the electrode lead.

(c) A twist-lock connector in the electrode lead.

The chosen method shall be tested prior to the commencement of work.

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19 AS 1674.2—2007


4.3 EARTHING

A licensed electrical worker shall ensure the frame of the power source is earthed in

accordance with AS/NZS 3000.

Wherever possible, all parts of the welding circuit shall be insulated from earth. The work

leads shall be connected in accordance with Clause 4.2.6. Failure to do so could seriously

compromise the integrity of the surrounding electrical installation or surrounding

mechanical componentry.

Under no circumstances shall any earthing conductor of the mains electrical installation be

used in place of the work or return conductor or lead.

4.4 CONNECTING MULTIPLE POWER SOURCES TO A COMMON

WORKPIECE

4.4.1 General

The diagrams shown in this Section are illustrated guides that do not show all possible

connections or the equipment that controls and protects the power sources.

The voltage between the electrode holders or torches of power sources connected to the

same workpiece can be up to twice the normal open-circuit voltage. This occurs where any

of the following apply:

(a) d.c. power sources of different polarity are connected.

(b) a.c. power sources are connected with primary leads opposed or out of phase.

(c) a.c. power sources are connected with secondary leads opposed and primary leads in

phase.

Where primary circuits on any adjacent machines are in phase, the output terminal of a.c.

welding power sources shall be connected in phase.

Where practicable, adjacent power sources should be connected to minimize voltage

between electrode holders or torches. It is the duty of authorized personnel to ensure that an

electric shock due to simultaneous contact with two electrode holders will not occur. The

open-circuit potential difference between the electrode holders or torches of adjacent

welding power sources should not exceed the values specified in Clause 3.2.6, unless

positive means, such as screens or barriers, are provided to prevent physical contact

between the welding circuits. It is desirable that screens and barriers be constructed of

electrically insulating materials.

A voltmeter should be used to determine whether an excessive voltage exists between

adjacent electrode holders. Alterations to connections between a.c. power sources and the

power supply can correct this problem, but only a licensed electrical worker is permitted to

carry out these changes.

4.4.2 Installation of single-phase power sources to two-wire a.c. supply circuits

Where power sources are installed adjacent to each other or where welders are required to

work in close proximity to one another, the power sources shall be connected for similar

instantaneous polarity and have similar connections onto the supply circuit. This results in

zero voltage with no load (open circuit) between output terminals or between electrode

holders or torches, assuming each power source to have the same open circuit voltage (see

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AS 1674.2—2007 20


NOTE: Supply connections 1 and 2 are either active and neutral respectively of a single-phase supply, or two phases

of a three-phase supply, depending on the voltage for which the power sources are designed.

FIGURE 4.4.2 TWO-WIRE a.c. SUPPLY

Where two power sources of the same polarity are connected in a reverse manner to the

supply circuit (see Figure 4.4.2(b)), the open-circuit voltage between electrode holders or

torches will be twice the open-circuit power source voltage.

The voltage between two such power sources may be readily checked by a voltmeter or a

test lamp, while both power sources are switched on and both work leads connected

together. If there is a potential difference significantly higher than zero between output

terminals or electrode holders or torches of adjacent power sources, the polarity of one of

the power sources shall be reversed by reversing the supply lead connections (see C and D

in Figure 4.4.2(b)).

4.4.3 d.c. welding circuits

Where direct-current welding power sources are connected to their respective electrode

terminals and electrode holders with opposite polarity, the power source open-circuit

voltages are additive and the potential difference between the electrode holders could equal

twice the normal open-circuit voltage of each power source.

Where the power sources are installed adjacent to each other or where welders using the

power sources are required to work in close proximity to one another, either the power

sources shall be connected for similar polarity of electrode holders or screens, or barriers

shall be provided to prevent physical contact between the welders.

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21 AS 1674.2—2007


4.4.4 Installations on three-phase supply circuits

The following precautions should be observed for installations supplying a.c. connected on

three-phase supply circuits:

(a) Where welders using single-phase power sources are required to work in close

proximity to each other, it is preferable for their power sources to be of the same

polarity and connected to the same two phases of the three-phase supply circuit. The

voltage between two such power sources may be readily checked by a voltmeter or a

test lamp, while the power sources are switched on. (See Figure 4.4.4.)

(b) Where two welders using single-phase power sources are required to work in close

proximity to each other and the capacity of the supply circuit makes it necessary to

connect their respective power sources to different phases of the three-phase supply

circuit, terminals of similar polarity on each of the power sources should be

connected to the common phase. A check shall be made with a voltmeter to ensure

that the potential difference between the electrode holders or torches connected to the

respective power sources does not exceed the open-circuit voltage of the individual

power sources. If the terminals of the power sources are not of the same polarity, or

connections to the primary or secondary windings are reversed, a potential difference

of 1.73 times the open-circuit power source voltage may be obtained. (See

Figure 4.4.4(b).)

(c) Where three single-phase power sources are each connected to a different phase of a

three-phase supply circuit and any two of the power sources are close to one another

or the welders using these power sources form a group working adjacent to each

other, if the capacity of the circuit permits, the safe connections as shown in

Figure 4.4.4(c) should be observed. For power sources of similar polarity, these

connections result in—

(i) zero voltage between power sources 1 and 2;

(ii) open-circuit power source voltage between power sources 2 and 3; and

(iii) open-circuit power source voltage between power sources 3 and 1.

(d) Where three single-phase power sources (or multiples of three) are each connected to

a different phase of three-phase supply-circuit and it is desired to balance the load

over the three phases, the safest connections are as shown in Figure 4.4.4(d). For

power sources of similar polarity, these connections result in—

(i) open-circuit power source voltage between power sources 1 and 2;

(i) open-circuit power source between power sources 1 and 3; and

(ii) 1.73 times the open-circuit power source voltage between power sources 2 and

3, in which case screens or barriers should be provided to prevent physical

contact between welders using the power sources 2 and 3.

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AS 1674.2—2007 22


FIGURE 4.4.4 (in part) CONNECTIONS TO THREE-PHASE SUPPLY CIRCUITS

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23 AS 1674.2—2007


FIGURE 4.4.4 (in part) CONNECTIONS TO THREE-PHASE SUPPLY CIRCUITS

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AS 1674.2—2007 24


S E C T I O N 5 I N S P E C T I O N A N D

M A I N T E N A N C E

5.1 POWER SOURCE

5.1.1 Routine inspection and testing

An inspection of the power source, an insulation resistance test and an earthing resistance

test shall be carried out—

(a) for transportable equipment, at least once every 3 months; and

(b) for fixed equipment, at least once every 12 months.

The owners of the machine shall keep a suitable record of the periodic tests and a system of

tagging, including the date of the most recent inspection.

NOTE: A transportable power source is any equipment that is not permanently connected and

fixed in the position in which it is operated.

5.1.2 Insulation resistance

Minimum insulation resistance for in-service welding power sources shall be measured at a

voltage of 500 V between the parts referred to in Table 5.1.2. Power sources with an

insulation resistance less than that specified, shall be withdrawn from service and not

returned until repairs have been made.

TABLE 5.1.2

MINIMUM INSULATION RESISTANCE

Parts to be tested Minimum insulation

resistance (MΩ)

Input circuit (including control

circuits connected to it)

To Welding circuit (including control


5

All circuits To Exposed conductive parts 2.5

Welding circuit (including control


To Any auxiliary circuit which operates at

a voltage exceeding extra low voltage

10

Welding circuit (including control


To Any auxiliary circuit which operates at

a voltage not exceeding extra low

voltage

1

Separate welding circuit To Separate welding circuit 1

Any control or auxiliary circuit connected to the protective conductor terminal shall be

considered as an exposed conductive part for the purpose of this test.

Conformity shall be checked by the stabilized measurement of the insulation resistance

without interference suppression or protection capacitors by application of a d.c. voltage of

500 V at room temperature.

NOTE: Solid state electronic components and their protective devices may be short-circuited

during the measurement.

A1

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25 AS 1674.2—2007


5.1.3 Earthing

The resistance shall not exceed 1 Ω between any metal of a power source, where such metal

is required to be earthed, and—

(a) the earth terminal of a fixed power source; or

(b) the earth terminal of the associated plug of a transportable power source; or

(c) the neutral terminal, if applicable (e.g. to confirm the integrity of the MEN link in

engine driven power sources).

NOTE: Because of the dangers of stray output currents damaging fixed wiring, every 12 months

the integrity of fixed wiring should be inspected by a licensed electrical worker in accordance

with Clause 5.1.1.

5.1.4 Repairs

Electrical work inside a welding power source shall be undertaken by a licensed electrical

worker.

5.2 ACCESSORIES

Accessory equipment, including output leads, electrode holders, torches, wire feeders and

the like, shall be inspected at least monthly by a competent person, to ensure that the

equipment is in a safe and serviceable condition. Unsafe and unserviceable accessories shall

not be used.

A1

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AS 1674.2—2007 26


APPENDIX A

TYPICAL ELECTRICAL HAZARDS

(Informative)

A1 SCOPE

This Appendix sets out to—

(a) create an understanding as to how electric shocks are received, so that welders may

be able to avoid them;

(b) describe the conditions that increase or decrease the severity of electric shocks; and

(c) explain the dangers of stray welding currents and how to avoid them.

A2 COURSES OF INSTRUCTION

Welding personnel should be given appropriate training in first aid.

Courses of instruction are available, including those provided by the following

organizations:

(a) Ambulance authorities.

(b) Australian Red Cross.

(c) National Heart Foundation Australia.

(d) Royal Life Saving Society Australia.

(e) St John Ambulance Australia.

(f) Surf Life Saving Australia.

NOTE: Further information about the physiological affects of electric shock on the human body is

given in WTIA Tech. Note 22.

A3 GENERAL

The operation of electric arc welding and allied process equipment is comparatively safe;

however, there are a number of electrical hazards that may cause electric shock and fire.

These hazards should be recognized by welders, to ensure safe operation.

Most welders have experienced electric shocks from welding circuits. Fortunately, the

majority of these shocks are only an unpleasant experience. Some electric shocks may cause

temporary injury, such as difficulty in breathing, heart rhythm disturbances, increase in

blood pressure or nerve damage. Often, shock is enough to cause secondary injury, such as

a fall from a height or a striking injury as a result of a sudden muscle spasm. In a few cases,

the result is death by electrocution. The most usual cause of such deaths is ventricular

fibrillation, when the heart rhythm is disrupted or stopped. Very small currents in the region

of the heart can cause this effect. Some deaths result from asphyxia, due to paralysis of the

lung or diaphragm muscles.

All parts of welding circuits, including output leads and work return paths, should be

considered electrically alive. Consequently, welders should ensure that no part of their body

is placed in such a position as would complete a conductive path for the passage of electric

current.

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27 AS 1674.2—2007


A4 POWER SOURCES

A4.1 General

Power sources include transformers, rectified transformers, inverters and electric motor

generators that are connected to a 415 V supply and diesel or petrol motor generators. They

may be designed for MMAW and similar processes with a drooping characteristic or for

GMAW and FCAW with a flat characteristic. Power source for SAW may have a flat or a

drooping characteristic.

Power sources should be in sound condition, properly installed, regularly inspected and

maintained in good working order.

A4.2 Open-circuit voltage

Although arc welding power sources are capable of supplying a wide range of current, they

generally operate within the following voltage ranges:

(a) For a.c. power sources, 40 V to 80 V.

(b) For d.c. power sources, 20 V to 100 V.

Power sources for MMAW and similar processes supply a higher open-circuit voltage

between the electrode and the work, when the welding power source is switched on and

ready to commence welding. These power sources have a drooping characteristic, with the

open-circuit voltage higher (often 60 V to 80 V) than when the arc is established and

welding current is drawn (20 V to 35 V). Consequently, the greatest danger occurs while

handling electrodes and the electrode holder between welding operations, such as while

changing electrodes.

Power sources for GMAW and FCAW have a flat characteristic, generally with a lower

open-circuit voltage (30 V to 50 V). Also, the current is turned on and off by a gun trigger,

which also controls the wire feed. Therefore, the welder is not exposed to open-circuit

voltage, unless the trigger is turned on and the wire is feeding. Also, electrodes are not

changed as frequently as for MMAW.

A4.3 Plasma welding and cutting

Plasma-arc welding is relatively safe, as the voltages are similar to other welding processes.

However in plasma-arc cutting, open-circuit voltages generally range up to 500 V d.c.

Plasma cutting equipment is designed so that the operator is not exposed to these voltages.

Welders and maintenance personnel should be aware that if plasma-arc cutting equipment is

mishandled, the higher voltages present a high risk.

Connecting the work cable to the workpiece as close as possible to the area being worked

upon and never touching the workpiece whilst cutting, minimizes the risk of electric shock

during the plasma cutting process.

A5 SECONDARY CIRCUITS

A5.1 General

An electric shock can be received when a person’s body is simultaneously in contact with

any exposed part of a secondary circuit electrode conductor and any metal or conducing

material connected to the work terminal. Figure A1(a) shows a safe situation, as well as an

unsafe situation with possible current paths through the welder’s body, while making

simultaneous contact with the electrode and the return circuit connection. This situation can

be fatal and can be avoided by observing safe working procedures.

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AS 1674.2—2007 28


The most exposed point of the electrode conductor in MMAW is the electrode tip, but

electrode coatings may also conduct electricity and should not be considered as safe

insulation. Damaged electrode holders, cables, connections and electrode core wire that is

bared by bending the electrode may also expose the welder to the circuit. GMAW, GTAW

and FCAW guns are generally better protected; however, the electrode tip may still be live.

Handling the gun and electrode with dry, hole-free gloves is essential.

Contacting the workpiece may be almost unavoidable. Usually the workpiece is in contact

with earth, either directly or via building structures and concrete floors. Floors (especially

when damp) and any other conducting materials with which the work is in contact may

become part of the welding circuit. Often the workpiece is a large structure, in which case

the welder and sometimes the welding power source are in direct contact with it.

The severity of an electric shock depends upon the following interrelated factors:

(a) The magnitude of the current flowing through the body.

(b) The path of the current passing through the body.

(c) The duration of the shock.

(d) The type of voltage supply (i.e., a.c. or d.c.).

(e) The reaction to shock by the victim.

A5.2 The magnitude of current flowing through a body

The amount of current that flows in an electrical circuit depends upon the applied voltage

and the electrical resistance of the circuit. The higher the voltage, the greater the amount of

current that will flow through any given resistance. Conversely, for a given voltage the

higher the resistance, the lower will be the flow of current.

In the event of a person touching an active conductor or electrode at the same time as

touching the work or return conductor with another part of the body, a circuit is completed

through the body and the amount of current that will flow depends upon the resistance that

the body offers to the applied voltage. The amount of current necessary to kill is only of the

order of 0.02 A. Welding circuits are designed to operate at thousands of times this level.

No protection is offered to welders in contact with the secondary circuit, by residual current

devices, fuses or earth leakage contact breakers fitted to the primary circuit of a welding

power source.

In general, the wetter the person’s skin and the larger the surface area of body contact, the

higher will be the current flowing through the body and, therefore, the greater will be the

risk of electrocution. In a Category B situation, voltages of the order of 48 V a.c. or more

may cause fatal shocks. Where there is dampness or perspiration, 25 V a.c. may be enough

to give a fatal shock.

The severity of electric shock is minimized by wearing dry gloves, rubber-soled shoes and

dry clothing, even if the body is damp and perspiring. The use of cotton liners that are

frequently changed to avoid welding gloves becoming saturated with perspiration is highly

recommended. Standing or sitting on a dry wooden floor, a dry rubber mat or similar

insulating material further enhances safety. Wherever practicable, insulating material

should be of a flame retardant type. The combined high resistance of insulating materials

offers a high degree of protection against shock; however, if body contact is made through

wet clothing, wet footwear or direct skin contact, with metal or other good conducting

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29 AS 1674.2—2007


FIGURE A1 TRANSFORMER TYPE WELDING CIRCUIT

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AS 1674.2—2007 30


A5.3 The path of current through a body

The most likely cause of death by electrocution is ventricular fibrillation (a disruption of

electrical stimulus of the heart muscle) causing its failure or muscle paralysis, leading to

respiratory arrest. Consequently, an electric shock through any part of the torso or the head

is regarded as serious. Where the entry and exit positions are remote from the torso or head,

there is a greater chance of survival.

A5.4 The duration of shock

The time during which current continues to flow through the body has a most important

bearing on survival. When breathing is disrupted or ventricular fibrillation occurs, death is

not instantaneous, but a few minutes delay may be fatal. The immediate isolation of the

power source is vital and prompt removal from the danger and treatment may save the

person’s life.

A5.5 The type of voltage supply

Alternating voltages are much more likely to cause serious shocks than direct voltages of

similar or higher magnitudes. The minimum direct current necessary to cause ventricular

fibrillation is three to five times the minimum level of alternating current at 50 Hz. Even

comparatively small currents are found to exercise a paralyzing effect on muscles, causing a

victim’s grip to tighten and make self-release difficult or impossible.

The threshold of perception and the threshold of reaction are significantly higher for d.c.

currents. AS/NZS 60479.1 uses an average value of 10 mA as the threshold of let-go for a.c.

currents. The threshold of let-go is defined as the maximum value of current at which a

person holding electrodes can let go of the electrodes. This means that in consideration of

the hazards associated with the use of a.c. power sources vs d.c. power sources it is a.c.

currents that approach the threshold of let-go that could lead to fatalities, rather than the

considerably higher currents that are considered to be the threshold of ventricular

fibrillation.

The threshold of let-go depends on several parameters, such as the contact area, the shape

and size of the electrodes and also on the physiological characteristics of the individual.

An average value of about 10 mA is assumed.

Unlike a.c. there is no definable threshold of let-go for d.c. Only the making and breaking

of current lead to painful and cramp-like contractions of the muscles.

A5.6 The reaction to shock

Reaction to a shock may make a victim suffer an instinctive muscle spasm, causing the

victim to move involuntarily. This can lead to a victim striking a nearby object or falling

from a height. Electric shocks can cause nerve damage and internal burns. The physical

condition of a victim has a bearing on the severity of a shock; however, even young

physically-healthy people have suffered electrocution from welding equipment.

A6 STRAY CURRENT

Where a welding circuit has a high electrical resistance, voltages are created, which may

cause currents to stray. This often occurs if leads, and in particular the return lead, are

poorly connected or become disconnected. In such a case, when a welder tries to strike the

arc, but it fails to ignite, the voltage of the workpiece is raised. This may cause a current to

find an alternate path back to the power source. The path it takes depends on the

circumstances and strange effects can occur, particularly if the workpiece is large, such as a

steel building or a ship.

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31 AS 1674.2—2007


Stray currents can cause the following problems:

(a) The current can track through other equipment not intended to carry welding current

and cause it to overheat and be damaged. Damage to lifting chains, wire-rope slings,

motor bearings, gearboxes and similar equipment has occurred in this way.

(b) The current can cause rapid corrosion to pipelines if it tracks through earth or water

containing these components. Rapid corrosion of a ship’s structure or of any structure

in contact with wet areas may occur in the same way.

(c) The current can cause burning out of electric wiring of equipment connected to the

workpiece, including the earth wiring, which may leave the equipment unprotected.

Destruction of the primary earth lead of power sources, power tools, lighting and

other equipment that is in contact with the workpiece has occurred.

(d) The current exposes others in contact with the workpiece to electric shocks, such as

the assistant holding a piece that is being tacked in place, or another worker at a

remote location.

(e) Poor connections in the circuit may overheat, which can cause overheating of

flammable materials, resulting in a fire. Electric wiring insulation in contact with

these hot spots can melt, allowing persons to contact mains voltages. Hoses

containing flammable gas or oxygen can melt, causing a hazardous leakage.

(f) Stray arc strikes at poor connection points can cause cracking of some metals.

A7 ELECTROMAGNETIC FIELDS AND PACEMAKERS

A7.1 General

Safe practices are particularly important to people wearing implanted pacemakers. Welders

who have been fitted with an implanted pacemaker and have decided to continue to cut or

weld should minimize their exposure to electric fields and magnetic fields and should

follow additional procedures (see Paragraphs A7.2 and A7.3), including adhering to any

advice from a doctor.

Some researchers have reported that exposure to electric fields or magnetic fields may

cause leukaemia or other illnesses. These claims originally arose in relation to high-voltage

electric power lines, but are very much in dispute in the medical and scientific arena. The

best precaution is to minimize any exposure to electric fields and magnetic fields. Any

advice by doctors should be heeded.

These procedures will not eliminate exposure to electric fields and magnetic fields or the

possibility of arc welding or plasma cutting having an effect on a pacemaker; however, they

will significantly reduce exposure to electric fields and magnetic fields.

It is not clear whether exposure to electric fields and magnetic fields can affect a person’s

health. Electric fields and magnetic fields have the following properties:

(a) They are created when electric current flows through a conductor.

(b) The field strength of direct current (d.c.) is relatively constant and does not change.

(c) The field strength of alternating current (a.c.) constantly changes.

(d) The greater the current flow (‘amps’), the stronger the field created by the current.

(e) The closer the conductor or electrical device is to the body, the greater the exposure

to the field.

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AS 1674.2—2007 32


A7.2 Minimizing exposure

Welders should use the following procedures to minimize exposure to electric fields and

magnetic fields:

(a) Position the torch or electrode and work cables together. Secure them with tape if

possible.

(b) Do not coil any torch or electrode lead around the body.

(c) Do not place the body between the torch or electrode and the work cables. Where the

torch or electrode cable is on the right side, position the work cable on the right side.

(d) Connect the work cable to the workpiece as close as possible to the area being worked

on. This is also good practice that will reduce the occurrence of poor work

connections, which is a common problem in welding and plasma cutting.

(e) Do not work next to a power source.

A7.3 Welders with pacemakers

Electrical fields in plasma cutting and arc welding can interfere with a pacemaker’s

function. Generally, such interference does not permanently damage the pacemaker. Once a

wearer leaves an arc welding environment or stops cutting or welding, the pacemaker

should operate normally. Welding arcs have little or no affect on the operation of some

types of pacemaker, especially designs that are bi-polar or designed to filter out such

interference.

Anyone who works near to electrical equipment and is going to be fitted with a pacemaker,

particularly a welder who wishes to continue plasma cutting or arc welding, should seek

advice from a doctor as to which would be an appropriate type of pacemaker to select. This

and any other questions should be discussed with a doctor, whose advice should be

followed. The doctor may wish to contact the manufacturer of the pacemaker for a

recommendation.

The design of pacemakers significantly affects the degree to which they are subject to

interference by a plasma or a welding circuit. The pacemaker should be insensitive to

interference from arcs, while still being medically suitable for the welder.

In addition to normal safety precautions, welders fitted with a pacemaker should adopt the

following additional procedures.

(a) Use gas cutting or gas welding where such a process is appropriate.

(b) Use the lowest current setting suitable for the application. Do not weld with more

than 400 A. Low (75 A to 200 A) direct current (d.c.) welding should be used if arc

welding is necessary. Do not use GTAW welding with a high frequency.

(c) Do not use repeated short cuts or welds. Wait about 10 s after stopping one cut or

weld, before starting the next. If having difficulty starting, do not re-strike repeatedly.

Find out the problem, then try again.

(d) If feeling light headed, dizzy or faint, immediately stop work, lay the torch or

electrode holder down so that it does not contact the work and move away from any

arcs. Work should be arranged in advance, so that, should dizziness develop and the

torch or electrode holder is dropped, the electrode will not fall on the body or strike

the work.

(e) Do not work on a ladder or other elevated position or in a cramped or confined place.

(f) Do not work alone. Work only in the presence of a person who understands the

precautions that should be observed and the possible effect that welding may have on

a pacemaker.

(g) Do not work near spot welding equipment.

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33 AS 1674.2—2007


A welder should not rely on the fact that another welder with a pacemaker had gone on for

years without experiencing a problem. That person and pacemaker may have operated in a

different situation, which may not be relevant.

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AS 1674.2—2007 34


APPENDIX B

FATAL ELECTRICAL ACCIDENTS

(Informative)

B1 INTRODUCTION

Open circuit voltages of less than 80 V a.c. are generally considered safe when working

under Category A environments.

When working in a Category B or a Category C environment, the risk is substantially

increased. Unfortunately, under these conditions, fatal accidents have occurred, even

though the welders have been in good health. The possibility of coming into contact with a

higher voltage on the supply side of a mains-operated power source should also be

considered. The circumstances of some fatal accidents are described below.

NOTES:

1 Many of these incidents involve a.c. power sources and MMAW in circumstances that do not

comply with this Standard.

2 It should be stressed that in most cases the equipment was examined and found to be in good

working condition.

B2 BOILER WELDING

The following three fatal accidents occurred to welders while they were working inside a

boiler, which would now be regarded as a Category C environment:

(a) Figure B1 shows a welder leaning against a boiler wall while fitting a new electrode.

While being fitted, the electrode slipped and touched the welder’s neck. After the

accident, current marks were found on the neck, back and soles of the feet.

Consequently, the current flow would have been from the neck through the torso to

the back and feet. While working in the closed room, the welder’s working clothes

had become soaked with perspiration, thus establishing a very good electric

connection to the boiler wall. The total resistance was estimated as being

approximately 250 Ω at the moment of the accident, and with a no-load voltage of

65 V at the transformer, the current would have been approximately 260 mA.

Currents of this magnitude can only be endured for up to 0.5 s but as the influence

would seem to have been of longer duration, the welder died.

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35 AS 1674.2—2007


FIGURE B1 ELECTRODE TOUCHING WELDER’S NECK ALLOWING

CURRENT TO PASS THROUGH THE TORSO TO THE BACK AND FEET

(b) Figure B2 shows a welder leaning back on a boiler wall, holding the electrode holder

under the arm. The perspiring back and armpit, in connection with an uninsulated

welding handle, caused current to flow from the armpit to the back. Because of the

small resistance at the contact points and the short current path, the resistance was

estimated at some 250 Ω at the moment of the accident. At a no-load voltage of 70 V

to 80 V, the current would have been approximately 300 mA. This proved fatal.

FIGURE B2 ELECTRODE UNDER WELDER’S ARM

CAUSING CURRENT FLOW FROM ARMPIT TO BACK

(c) A faulty cable caused this accident. Figure B3 shows a welder leaning a perspiring

back against the boiler wall. While touching the faulty cable, the welder received a

cramp and pressed the cable against the chest. Thus a chest-to-back electric contact

was established. The resistance was estimated to have been approximately 200 Ω and,

at a voltage of 70 V, the current was approximately 350 mA at the moment of the

accident. This proved fatal.

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AS 1674.2—2007 36


FIGURE B3 FAULTY CABLE CAUSING CURRENT

FLOW FROM CHEST TO BACK

B3 WORKING ON BOARD A SHIP

The following two fatal accidents occurred to welders while working on board a ship, in a

Category C environment (see Clause 1.3.6.3):

(a) Figure B4 shows a welder working in a vent shaft of a ship being built, while

kneeling at the bottom of the vent shaft where pools of rainwater collected after it had

rained. While fitting a new electrode, the electrode slipped and hit near one eye. After

the accident, current marks were found on the welder’s knees and in the eye region.

Since the knees presented a comparatively small area, a comparatively large pressure

(approximately 85 percent of the body weight) had been pressed down against the

moist metal base. The contact resistance was low and the total resistance was

estimated at approximately 600 Ω at the moment of the accident.

At a no-load voltage at the welding transformer of 75 V, the current was calculated at

approximately 125 mA at the moment of the accident.

NOTE: A current of 125 mA is dangerous to life if it flows for more than 0.8 s.

FIGURE B4 ELECTRODE MAKES CONTACT WITH FACE CAUSING CURRENT FLOW

THROUGH TORSO TO KNEES

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37 AS 1674.2—2007


(b) Figure B5 shows a welder lying on a raft, carrying out repair work on the outside of a

ship’s hull. To assist the welder and ensure that no accident would occur, an assistant

had been placed on a ladder close to the welder. The welder was finishing the work

when a large wave flooded the raft and the welder. The startled welder dropped the

electrode and holder onto the chest, causing an electric contact to be established

through the body and the salt water. The welder fell into the water, but was soon

pulled out onto the raft by the assistant, who immediately administered artificial

respiration; however, the welder could not be saved. The resistance in the circuit was

estimated at approximately 700 Ω and, at a no-load voltage of 70 V, the current was

approximately 100 mA. This was sufficient to cause a fatality.

FIGURE B5 WELDER ON RAFT FLOODED BY WAVE

B4 WELDING OUTDOORS

Figure B6 shows an accident during outdoor welding work. The welder and the assistant

were both standing on a base that was electrically connected to the welding transformer

work return lead. It was raining, so it was a Category C environment (see Clause 1.3.6.3).

The assistant handed a metal object to the welder and, at the moment the welder touched it,

both received an electric shock. Through analysis of the current marks, it was found that the

current had passed through the assistant’s footwear, the assistant’s body, the metal object

and the welder’s body to the electrode where the insulation was poor. Due to the many

contact resistances and the comparatively long current path, the total resistance was

estimated at 1900 Ω. Since the transformer no-load voltage was 67 V, the current would

have been approximately 35 mA. Currents of this magnitude are usually regarded as being

harmless. In this case, the assistant got off with a shock, whereas the welder died. This

demonstrates that two people may react differently to the same current influence and that

consideration should be given to the varying body build and health condition of different

people. The welder may have had a non-recognized heart condition, which proved decisive

to the course of the accident when exposed to the current.

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AS 1674.2—2007 38


FIGURE B6 WELDER HOLDING ELECTRODE IS HANDED METAL OBJECT BY

ASSISTANT CAUSING CURRENT FLOW THROUGH THEM BOTH

B5 PULLING A CABLE

Figure B7 shows a welder pulling a live cable up to the welding point by putting it over the

shoulder. Due to a faulty cable insulation and poor footwear insulation, the welder received

an electric shock and fell. Thus, contact was established from the head and chest to the

cable on the shoulder. The resistance was estimated at approximately 200 Ω at the moment

of the accident and, at a no-load voltage of 67 V, the current would have been

approximately 335 mA. This proved fatal.

FIGURE B7 WELDER PULLED FAULTY CABLE OVER SHOULDER AND RECEIVED

FATAL SHOCK

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39 AS 1674.2—2007


B6 FATAL ELECTRICAL ACCIDENT INVOLVING MAINS VOLTAGE

Figure B8 shows the power supply cord resting on an overhead terminal of a power source.

The PVC insulation of the power supply cord melted, allowing the active conductor of the

cord to contact the work terminal, thus energizing the welding circuit and the work at mains

voltage.

The welder, who was barefooted, touched the work with the hand, and a circuit was

completed through the body to earth.

At a voltage to earth of approximately 240 V, the current that flowed through the body

proved fatal.

FIGURE B8 MAINS SUPPLY ELECTROCUTES WELDER THROUGH HOT TERMINAL

ON POWER SOURCE MELTING INSULATION

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AS 1674.2—2007 40

AMENDMENT CONTROL SHEET

AS 1674.2—2007

Amendment No. 1 (2011)

CORRECTION

SUMMARY: This Amendment applies to Clauses 5.1.2 and 5.1.3.

Published on 15 February 2011.

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Standards Australia Standards Australia develops Australian Standards® and other documents of public benefit and national interest. These Standards are developed through an open process of consultation and consensus, in which all interested parties are invited to participate. Through a Memorandum of Understanding with the Commonwealth Government, Standards Australia is recognized as Australia’s peak non-government national standards body. Standards Australia also supports excellence in design and innovation through the Australian Design Awards. For further information visit www.standards.org.au Australian Standards® Committees of experts from industry, governments, consumers and other relevant sectors prepare Australian Standards. The requirements or recommendations contained in published Standards are a consensus of the views of representative interests and also take account of comments received from other sources. They reflect the latest scientific and industry experience. Australian Standards are kept under continuous review after publication and are updated regularly to take account of changing technology. International Involvement Standards Australia is responsible for ensuring the Australian viewpoint is considered in the formulation of International Standards and that the latest international experience is incorporated in national Standards. This role is vital in assisting local industry to compete in international markets. Standards Australia represents Australia at both the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). Sales and Distribution Australian Standards®, Handbooks and other documents developed by Standards Australia are printed and distributed under license by SAI Global Limited.

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For information regarding the development of Standards contact: Standards Australia Limited GPO Box 476 Sydney NSW 2001 Phone: 02 9237 6000 Fax: 02 9237 6010 Email: [email protected] Internet: www.standards.org.au For information regarding the sale and distribution of Standards contact: SAI Global Limited Phone: 13 12 42 Fax: 1300 65 49 49 Email: [email protected]

ISBN 0 7337 8142 X

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AS 1674.2-2007 Safety in welding and allied processes ...

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