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Australian Electrical Equipment In Hazardous Areas Standards(Gas)

This is an updated version (Feb 2008) of a paper presented at a IICA seminar 'Power & Control Equipment in Hazardous Locations', Perth, 16-17Sep 1986. It is in my opinion a very useful guideline for working within the standards associated with electrical equipment in hazardous areas. ICEweb acknowledges the assistance and review of the document by Inlec Engineering

Australian Standards for Electrical Apparatus in Hazardous Areas- Explosive Gas Areas

J A Russell IEng, FIICA

Introduction

This paper takes a practical approach to Australian Hazardous Area Standards taking the reader through them from conceptual design to maintenance. It does not cover dust hazards.

Australian Standards must be regarded as the PRIME Hazardous Area design guide in Australia. Some engineers are unnecessarily critical of the Standards, but these documents must be respected for what they are, namely information and advice dossiers which have been built up from design and practical experience over the years not only in Australia but from international sources (most Australian Standards have been based on the International Electrotechnical Commission [IEC] and the British Standards Institution [BSI] Standards).

Foreign Standards are not a substitute for Australian Standards. The only circumstances warranting the use of Foreign Standards is where the equipment is not available in an Australian certified form.  It should be noted that the use of foreign standards may require specific approval from an authority relevant to the particular industry.

AS/NZS3000-2007 -Electrical Installations - The Australian and New Zealand Wiring Rules is the most important Australian Standard pertaining to Electrical Installations in Hazardous Areas. Compliance with this Standard is mandatory under certain Federal and State Acts.

The Australian Standards can be of tremendous assistance to anyone involved in a Hazardous Area environment from engineers and technicians to fitters and process personnel. Admittedly they do have some limitations but which document doesn't.

In this paper some limitations of the Standards are detailed to foster awareness, however it is not intended to be derogatory to Standards Australia.

Hazardous dust atmospheres, although not part of the scope of this paper, are mentioned.

Australian Standards for Electrical Apparatus in Hazardous Areas - HA Standard Application Use and Limitations

Hazardous Area Design

Primarily the design engineering group must be in possession of the following

a) An adequate Scope of Work and process description

b) Process and Instrumentation diagrams (P & ID's)

c) Plant layouts and elevations

If these documents are not available design should not proceed.

This base documentation is utilised in conjunction with AS/NZS60079.10 CLASSIFICATION OF HAZARDOUS AREAS - Explosive Gas Atmospheres (Replaces AS2430.1) to determine the extent and degree of the hazard. 

The following definitions are important to remember, see Table 1.

TABLE 1

AS/NZS60079.10  EXPLOSIVE GAS ATMOSPHERES  (Replaces AS2430.1)

Gas areas are subdivided into zones as follow;

ZONE 0 - In which an explosive atmosphere is present continuously, or is expected to be present for long periods, or for short periods which occur at high frequency. (More than 1000 hours per year)

ZONE 1 - In which an explosive gas atmosphere can be expected to occur periodically or occasionally during normal operation. (More than 10 hours per year but less than 1000 hours per year)

ZONE 2 - In which an explosive gas atmosphere is not expected to occur in normal operation and when it occurs is likely to be present only infrequently and for short duration. (Less than 10 hours per year)

NOTE: For the full definitions refer to the above Standard

Classification of Hazardous Areas

Initial classification of the Hazardous Areas should be carried out by Process or Chemical Engineers as they are more familiar with the source/quantity of release, source or ignition, flashpoint, ignition temperature and plant operation concepts.

It is recommended that any engineer, even if he has used the Standard before, reads it several times prior to attempting to classify zones.

Competency for working with electrical equipment for hazardous areas is critical and there are several providers who undertake training and assessment in this area. 
These include: 
Inlec Engineering see:  http://www.inleceng.com/ 
Moxi Skill + Learning, see www.moxi.com.au/products.htm 

Courses and Assessment are based on the following standard:
AS/NZS4761 - Competency for working with electrical equipment for hazardous areas 
Part 1 - Competency Standards - Note updated June 2008 
Part 2 - Guide for Training and Assessment - Note updated June 2008 

MP 87:2004 : Australian/New Zealand Certification Scheme for explosion-protected electrical equipment (ANZEx Scheme) - Contains the basic rules and procedures for the management, administration and operation of the Australian/New Zealand Certification Scheme (ANZEx Scheme) for explosion-protected electrical equipment.

The " base" drawings utilised for the Hazardous Area drawings are usually the "to scale" plant layouts and elevations.

The engineer responsible for classification then classifies the plant area in accordance with the following standards. These Standards are only a guide and under no circumstances cover all plant concepts. They do however cover the most common ones. From these examples it is usually possible to deduce the Hazardous Area for an unusual portion of plant. In these circumstances it is important to document the reasons for determining a particular Hazardous Area.

Classification of Hazardous Areas - Liquids, Gases & Vapours
AS/NZS60079.10- Explosive Gas Atmospheres
AS/NZS 60079.10.1 Explosive atmospheres - Classification of Areas - Explosive gas atmospheres - October 2009 -  Supersedes the 2004 edition of AS/NZS 60079.10 and the AS/NZS 2430.3 series of standards.

AS/NZS60079.20 - Data for flammable gases and vapours

Hazardous Area drawings should detail the source of release, gas group and temperature class and show the Hazardous Area in "cross hatching" as shown in AS/NZS60079.10.

On completion of the initial Hazardous Area drawings the responsible Engineer should pass co-ordination prints to the Electrical, Instrumentation, Mechanical and Safety Engineers. These personnel are responsible for reviewing and checking the document in relation to their own discipline.

The final "Issued for Construction" drawing should then again be reviewed and signed by the responsible Engineer of all the pertinent disciplines.

This group involvement cannot be stressed enough since if the requirements of the Standard are not met expensive remedial work may be required later in the project.

Electrical Equipment for Hazardous Areas Protection Concepts

On completion the Hazardous Area drawings are utilised by the Electrical/instrumentation Engineers for the system design along with AS/NZS2381.1 Electrical Equipment for Explosive Gas Atmospheres - selection, installation and maintenance.

It cannot be overemphasised that the person responsible for the Standard library within a company must inform the discipline engineers of any update or superseding of Standards. All too often engineers are left in the dark and are working to out of date Standards.

AS/NZS2381.1 "General Requirements" should be read first, this part along with the other parts relevant to the specific technique are applied in new installations, changes to existing installations whether permanent or temporary, and in maintaining equipment.

The Engineer after referencing the Hazardous Area drawings regarding location, zoning, gas groups and surface temperatures should select the equipment design according to the requirements of AS/NZS2381.1 . An important aspect of this is the comprehension of equipment labelling. (see Table 2).

TABLE 2

EXPLOSION PROTECTION

TYPE OF PROTECTION GASGROUP TEMPERATURE CLASSIFICATION
Exd- Flameproof I (methane - mining only) T1 –450OC
Exi- Intrinsically safe IIA (Propane) T2-300OC
Exp- Pressurisation IIB (Ethylene) T3-2000C
Exe- Increased safety IIC (Hydrogen) T4-1350C
Exm- Encapsulation T5-1000C
Exn- Non-incendive T6- 850C
Exs- Special Protection
Exo- Oil Immersed
Exq- Powder/sand filled
Exv- Ventilation
NOTES:
  1. The certificate number AUSEx...,ANZEx...or IECEx....must be on the label or the certification may not be acceptable.
  2. If the label is headed EEx the equipment is certified to European norms.
  3. Standards Australia publish a list of Australian certified equipment, this can be found at www.anzex.com.au 
  4. SAFE AREA Apparatus associated with intrinsically safe circuits is distinguished by the marking "ia", "ib"or"Exia", Ëxib" within brackets. e.g. Ex(ia), Ex(ib), (Exia), (Exib).

European equipment is bracketed with square brackets [EExia].

IT MUST BE NOTED THAT EQUIPMENT MARKED WITH THESE BRACKETS IS NOT IN ITSELF INTRINSICALLY SAFE AND THUS MUST NOT BE MOUNTED IN A HAZARDOUS AREA WITHOUT ALTERNATIVE PROTECTION!

As an aid to selecting the particular equipment or Australian Standard for a certain zone the easy reference guide Table 3 can be utilised. The relevant Standard pertaining to the selected equipment should then be read.

Table 3

EQUIPMENT AND STANDARD SELECTION

It should be noted that AS/NZS2381.1 gives general installation guidelines. When no other standard is detailed in this table there is no specific installation standard for the technique. Thus the installer must refer to the apparatus standard for guideance.  

In addition the Australian standards should be fully read and understood in line with the competency provisions outlined previously in this document. The standards can be obtained from http://www.sai-global.com/shop/script/Search.asp 

ZONE 0
Exia (Intrinsically Safe)
Apparatus Standards

AS/NZS 60079.11
AS 2380.7
Installation Standards
AS/NZS 60079.14-Explosive atmospheres - Electrical installations design, selection and erection. 
AS/NZS 2381.1
AS 2381.7
AS/NZS 60078.25

Inspection and Maintenance
AS/NZS 60079.17-2009 Explosive atmospheres - Electrical installations inspection and maintenance 

Exma (Encapsulation-level of protection a)
Apparatus Standard
AS/NZS 60079.18
Installation Standard
AS/NZS 60079.14- Explosive atmospheres - Electrical installations design, selection and erection. 
Inspection and Maintenance
AS/NZS 60079.17-2009 Explosive atmospheres - Electrical installations inspection and maintenance 

Exs (Special Protection)
Clearly marked for the relevant zone ie., specifically marked for Zone 0 use.

Apparatus Standard
AS/NZS 1826(Int) 
AS/NZS 60079.33:2012 - Explosive Atmospheres - Equipment Protection by Special Protection ‘S’ - The objective of this Standard is to provide requirements and the specific methodology for the assessment, testing and marking of electrical equipment, parts of electrical equipment and Ex components with special protection ‘s’.
Installation Standards
AS/NZS 60079.14-2009 Explosive atmospheres - Electrical installations design, selection and erection. 
AS/NZS 2381.1
AS 1076.8
Inspection and Maintenance
AS/NZS 60079.17-2009 Explosive atmospheres - Electrical installations inspection and maintenance 

ZONE 1
All Zone 0 techniques plus

Exib (Intrinsically Safe)

Apparatus Standard
AS2380.7
AS/NZS 60079.11
Installation Standards
AS/NZS 60079.14 - Explosive atmospheres - Electrical installations design, selection and erection. 
AS/NZS 2381.1
AS 2381.7
AS/NZS 60078.25
Inspection and Maintenance
AS/NZS 60079.17-2009 Explosive atmospheres - Electrical installations inspection and maintenance 

Exd (Flameproof)
Apparatus Standard
AS/NZS60079.1
AS 2380.2
Installation Standards
AS/NZS 60079.14- Explosive atmospheres - Electrical installations design, selection and erection. 
AS/NZS 2381.1
AS/NZS 2381.2 Electrical equipment for explosive atmospheres - Selection, installation and maintenance - Flameproof enclosure 'd' 
Inspection and Maintenance
AS/NZS 60079.17-2009 Explosive atmospheres - Electrical installations inspection and maintenance 

Exe (Increased Safety)
Apparatus Standards
AS/NZS 60079.7 
AS 2380.6
Installation Standards
AS/NZS 60079.14 - Explosive atmospheres - Electrical installations design, selection and erection. 
AS/NZS 2381.1
AS2381.6
Inspection and Maintenance
AS/NZS 60079.17-2009 Explosive atmospheres - Electrical installations inspection and maintenance 

Exm (Encapsulation)
Apparatus Standards
AS/NZS 60079.18
Installation Standards
AS/NZS 60079.14- Explosive atmospheres - Electrical installations design, selection and erection. 
AS/NZS 2381.1
Inspection and Maintenance
AS/NZS 60079.17-2009 Explosive atmospheres - Electrical installations inspection and maintenance 

Exmb (Encapsulation-level of protection b)
Apparatus Standard
AS/NZS 60079.18
Installation Standard
AS/NZS 60079.14-Explosive atmospheres - Electrical installations design, selection and erection. 
AS/NZS 2381.1
Inspection and Maintenance
AS/NZS 60079.17-2009 Explosive atmospheres - Electrical installations inspection and maintenance 

Exp (Pressurisation)-when installed to Zone 1 requirements.
Apparatus Standard
AS2380.4
AS/NZS 60079.2
Installation Standard
AS/NZS 60079.14 - Explosive atmospheres - Electrical installations design, selection and erection. 
AS/NZS 2381.1
Inspection and Maintenance
AS/NZS 60079.17-2009 Explosive atmospheres - Electrical installations inspection and maintenance 

Exv (Ventilation)-when installed to Zone 1 requirements.
Apparatus Standards
AS 1482
Installation Standards
AS/NZS 60079.14- Explosive atmospheres - Electrical installations design, selection and erection. 
AS/NZS2381.1
Inspection and Maintenance
AS/NZS 60079.17-2009 Explosive atmospheres - Electrical installations inspection and maintenance 
Inspection and Maintenance
AS/NZS 60079.17-2009 Explosive atmospheres - Electrical installations inspection and maintenance 

Exs (Special Protection)
Clearly marked for the relevant zone ie., specifically marked for Zone
1 use.
Apparatus Standard
AS/NZS1826(Int)
AS/NZS 60079.33:2012 - Explosive Atmospheres - Equipment Protection by Special Protection ‘S’ - The objective of this Standard is to provide requirements and the specific methodology for the assessment, testing and marking of electrical equipment, parts of electrical equipment and Ex components with special protection ‘s’.
Installation Standards
AS/NZS 60079.14-Explosive atmospheres - Electrical installations design, selection and erection. 
AS/NZS 2381.1
AS 1076.8
Inspection and Maintenance
AS/NZS 60079.17 - Explosive atmospheres - Electrical installations inspection and maintenance 

Fieldbus Intrinsically Safe Concept (FISCO)
Apparatus, Systems and Installation Practice
AS/NZS 60079.27
Inspection and Maintenance
AS/NZS 60079.17 - Explosive atmospheres - Electrical installations inspection and maintenance 

Exo (Oil Immersion)
Apparatus Standard
AS/NZS60079.6
Installation Standards
AS/NZS 60079.14-Explosive atmospheres - Electrical installations design, selection and erection. 
AS/NZS2381.1
Inspection and Maintenance
AS/NZS 60079.17 - Explosive atmospheres - Electrical installations inspection and maintenance 

Exq (Powder Filling)
Apparatus Standard
AS/NZS60079.5
Installation Standards
AS/NZS 60079.14-Explosive atmospheres - Electrical installations design, selection and erection. 
AS/NZS2381.1
Inspection and Maintenance
AS/NZS 60079.17 - Explosive atmospheres - Electrical installations inspection and maintenance 

ZONE 2
All Zone 0 and 1 techniques plus

Exn (Non incendive)
Apparatus Standard
AS/NZS 60079.15 - Electrical apparatus for explosive gas atmospheres - Construction, test and marking of type of protection, ‘n’ electrical apparatus.
Installation Standards
AS/NZS 60079.14-Explosive atmospheres - Electrical installations design, selection and erection.
AS/NZS 2381.1
AS1076.7
Inspection and Maintenance
AS/NZS 60079.17 - Explosive atmospheres - Electrical installations inspection and maintenance 

Exp (Pressurisation)-when installed to Zone 2 requirements.
Apparatus Standard
AS2380.4
AS/NZS 60079.2
Installation Standard
AS/NZS 60079.14-Explosive atmospheres - Electrical installations design, selection and erection. 
AS/NZS 2381.1
Inspection and Maintenance
AS/NZS 60079.17 - Explosive atmospheres - Electrical installations inspection and maintenance 

Exv (Ventilation)-when installed to Zone 2 requirements.
Apparatus Standard
AS 1482
Installation Standard
AS/NZS 60079.14-Explosive atmospheres - Electrical installations design, selection and erection. 
AS/NZS 2381.1
Inspection and Maintenance
AS/NZS 60079.17 - Explosive atmospheres - Electrical installations inspection and maintenance 

Exs (Special Protection)
Clearly marked for the relevant zone ie., specifically marked for Zone 2 use.

Apparatus Standard
AS/NZS 1826(Int)
AS/NZS 60079.33:2012 - Explosive Atmospheres - Equipment Protection by Special Protection ‘S’ - The objective of this Standard is to provide requirements and the specific methodology for the assessment, testing and marking of electrical equipment, parts of electrical equipment and Ex components with special protection ‘s’.
Installation Standard
AS/NZS 60079.14-Explosive atmospheres - Electrical installations design, selection and erection. 
AS1076.8
Inspection and Maintenance
AS/NZS 60079.17 - Explosive atmospheres - Electrical installations inspection and maintenance 

Ex'o-oil immersion" is a technique used occasionally for switchgear and transformers. There is not widespread use of this technique. Ex'q-powder filling"technique is not common.

Fieldbus Non Incendive Concept (FNICO)
Apparatus, Systems and Installation Practice
AS/NZS 60079.27
Inspection and Maintenance
AS/NZS 60079.17 - Explosive atmospheres - Electrical installations inspection and maintenance 
Inspection and Maintenance
AS/NZS 60079.17 - Explosive atmospheres - Electrical installations inspection and maintenance 

On selection of equipment the vendor should be requested to supply a copy of the relevant Certificate of Conformity PRIOR to orders being placed.
The responsible engineer should read the certificate for the following reasons:-

1. To ensure it is the correct document for the equipment, (all too often vendors supply incorrect certificates).

2. To comply with any "conditions of use" stated on the certificate. 

When the certification has been reviewed it should be filed for entry into the verification dossier. The engineer can then proceed with the circuit\system design in accordance with the equipment certificates and relevant Standards.

Hazardous Area Installations Verification Dossiers

It is essential that a verification dossier is prepared for all Hazardous Area installations. Included in this dossier should be:-

a. Hazardous Area drawings

b. Certification schedule

c. Equipment certificates

d The engineering calculations pertaining to Intrinsically Safe loops

e. Cable schedules and Cable routes

g. Special tests to be carried out upon Installation/Commissioning

h. Inspection report on installation

i. Periodic inspection reports.

The dossier must be updated during the life of the plant reflecting any changes which are implemented pertaining to the installation and equipment within the Hazardous Area.

The engineer responsible for the Hazardous Area drawings must be advised of any minor/major piping changes since these could result in changes to the Hazardous Area classification.
A full listing is available in AS2381.1 clause 1.6

Electrical Equipment in Hazardous Areas Installation and Maintenance

AS/NZS 60079.17 - Explosive atmospheres - Electrical installations inspection and maintenance 

AS/NZS3000 AUSTRALIAN AND NEW ZEALAND WIRING RULES and its associated Standards must be read at length and understood by the construction and maintenance engineers. Technicians and fitters should also be conversant with the requirements of the standard.

On a plant which is old or has been poorly maintained it is very important that the Company institutes an inspection to ensure compliance. In order to achieve this it will be necessary to have up to date Hazardous Area drawings and certification schedules. If these drawings are not available they should be produced.

The recommendations of the inspection report should be discussed with both maintenance, installation, design engineers and plant management.

An important clause to remember that no equipment which is in an unsafe condition shall be connected or remain connected to an installation". In other words if there is a non compliance problem fix it or disconnect it.

Electrical staff should be fully conversant with and receive periodical updates in the principles of electrical equipment protection concepts. It is essential that personnel are aware of the certification limitations of test equipment since being portable this equipment is more likely to constitute a hazard in that it can be used in zones for which it is not certified.

Frictional Sparking Risks with Light Metals and their Alloys is very important and often misunderstood. This hazard is due to sparking when light metals and their alloys come into frictional contact with materials which are oxygen carriers, rust being the most common.

NO light metal alloy is permitted in a Zone 0 area. Fixed light metal alloy equipment is permitted in other zones subject to impact protection. Portable equipment of these materials is NOT permitted in Hazardous Areas unless equipment is otherwise protected (i.e. plastic coated or epoxy painted). A frequent breach of regulations can be seen with aluminium foil. aluminium scaffolding, aluminium sunshades, aluminium paint and the "old style" aluminium hard hats.

Repair and Overhaul of Electrical Equipment in Hazardous Areas

AS/NZS 3800:2012 - Electrical equipment for explosive atmospheres - Repair and overhaul - This Standard
(a) specifies requirements for and gives instructions, principally of a technical nature, on the repair, overhaul, reclamation and modification of equipment designed for use in explosive atmospheres;
(b) is not applicable to maintenance, other than when repair and overhaul cannot be disassociated from maintenance, neither does it give advice on cable entry systems which may require a renewal when the equipment is re-installed;
(c) prevents overhaul without manufacturer and certificate documentation to types of protection ‘i’ and ‘m’; and
(d) assumes that good engineering practices are adopted throughout.

Inspection of Electrical Equipment in Hazardous Areas

Inspection of Electrical Equipment prior to/during and periodically after installation is ESSENTIAL. AS2381 reflects the importance that the Standards Australia place on inspection with each of the sections detailing typical "Inspection" schedules. Generally these inspection schedules are combined into an overall schedule for the plant.

AS/NZS 60079.17 - Explosive atmospheres - Electrical installations inspection and maintenance 

Inspection intervals should not exceed four years.

Limitations of Australian Hazardous Area Standards

There are several notable areas which are not covered by Australian Standards these are-

(1) ANALYSER HOUSES

Analyser Houses have been in use for many years and to date no Australian Standard has been issued specifically referring to what can be a very hazardous environment. AS2380.4 (Pressurisation) instructs the user to refer to IEC 79-16 for analyser houses which details how to design these enclosures utilising ventilation concepts.

Although not a standard the document "Electrical Installations in Flammable Atmospheres" published by the Royal Society for the Prevention of Accidents has a very useful section on Analyser Houses.

(2) IGNITION FIRED GAS ENGINES

This is another complex subject which certainly merits inclusion in a Standard.

USEFUL REFERENCES

Selection, installation and maintenance guidelines for Ignition Systems used in Class 1, Group D, Division 2 locations on Internal Combustion Engines published by the American Gas Association

(3) GAS FIRED BOILERS IN INDUSTRIAL HAZARDOUS AREAS

There are no firm guidelines for the zoning of the above extremely confusing subject which causes great deal of "heartache" to many engineers. It is often difficult to zone an area where there may be for example, open flames protected by flame arrestors and high exhaust temperatures as a fundamental part of the apparatus.

Any engineer who believes that limitations exist in the Standards pertaining to the area in which he is working should first check with the Australian Standards catalogue of Standards Australia publications www.standards.org , ensuring that Standard on the subject has not been issued.

If no Australian Standard is available then other reference/foreign Standards should be sought. The proposed design should then be discussed and agreed upon by the responsible engineers. Any engineering decisions taken must be fully documented and included in the plant certification dossier.

Other Useful Standards and Handbooks

AS/NZS 2229 Fuel dispensing equipment for explosive atmospheres

 AS/NZS 60079.28:  Protection of equipment and transmission systems using optical radiation 

Electrical Equipment for Hazardous Areas Handbook HB2007 - from Standards Australia, the main objective of this updated handbook is to provide a basis for understanding the principles involved in the identification of a hazardous area, relevant statutory requirements and the selection and installation, maintenance, testing, overhaul and repair of appropriate electrical equipment. This handbook also provides a basic introduction to the relevant Australian, New Zealand, Joint (Australian/New Zealand) and International Standards dealing with hazardous areas.

Gas Detection

AS/NZS 60079.29.1 - Explosive atmospheres - Gas detectors - Performance requirements of detectors for flammable gases.
AS/NZS 60079.29.2:2008 - Explosive atmospheres - Gas detectors - Selection, installation, use and maintenance of detectors for flammable gases and oxygen.
AS/NZS 60079.29.4:2011- Explosive Atmospheres - Gas Detectors - Performance requirements of open path detectors for flammable gases.
IEC 60079-29-4  - Explosive atmospheres, Part 29-4: Gas detectors—Performance requirements of open path detectors for flammable gases.

Foreign Ex Standards

It should not be generally required to refer to foreign Standards in association with new installations except in special circumstances which are detailed in the following Foreign Certification section. However on older installations it is quite likely that foreign, often American equipment, has been installed. It is therefore necessary to understand the labelling of this equipment to ensure its suitability for the zone in which it has been installed.

Comparisons of Standards are detailed in Tables 4,5 and 6. Care must be taken with these comparison tables detailed since although generally true some countries have gases/materials in different classes/groupings to others. Classification techniques also vary from country to country.

Table 4

NATURE OF HAZARD

AUSTRALIA
AS/NZS60079.10
USA
NEC*
Flammable gases, liquids and vapours
Note Classes no longer exist
Class I**
*NEC - National Electric Code
**Class 1 (USA) - Locations which are hazardous because of the presence of flammable gases, vapours and mists

Table 5

AREA CLASSIFICATION

AUSTRALIA

AS2430/60079
Zone 0
Zone 1
Zone 2

USA

NEC
Division 1*
Division 1
Division 2**

IEC/CENELEC

IEC79/CENELEC31
Zone 0
Zone 1
Zone 2

GFR

VDE
Zone 0
Zone 1
Zone 2

*Division 1 USA - Areas which are likely to contain flammable atmospheres in normal operation.
**Division 2 - areas which are likely to contain flammable atmospheres only in abnormal operation.

Table 6

HAZARDOUS MATERIALS -GAS GROUPING

Australia
USA
NEC
IEC/CENELEC
60079
GFR
VDE 0171
AS 2430/ 60079 GAS TYPE
IIA
IIB
IIC
IIC
D
C
B
A
IIA
IIB
IIC
IIC
*(1)IIA
*(2)IIB
*(3a)IIC
*(3b, c, n)
Propane etc
Ethylene etc
Hydrogen
Acetylene
*Superseded standard

TABLE 7

SURFACE TEMPERATURE CLASSES

Australia
AS/NZS60079
USA
NEC
IEC/CENELEC
60079
GFR
VDE
T1 (450OC) T1 (450OC) T1 *(G1) T1
T2(300OC) T2 (300OC)
T2A(280OC)
T2B(260OC)
T2C(230OC)
T2D(215OC)
T2 *(G2) T2
T3(200OC) T3 (200OC)
T3A(l 80OC)
T3B(165OC)
T3C(l60OC)
T3 *(G3n) T3
T4 (135OC) T4 (135OC)
T4A(120OC)
T4 *(G4) T4
T5 (100OC) T5 (100OC) T5 *(G5) T5
T6 ( 85OC) T6 (85OC) T6 T6
*() Superseded Standard

Foreign Certification

If available, equipment with Australian/International AUSEx/ANZEx or IECEx certification should be selected and installed in compliance with Australian Standards. To select foreign certified equipment on the basis of lower cost is false economy since documentation costs are likely to exceed any savings.

Sometimes however AUS/ANZ/IECEx certified equipment is not available and alternative equipment must be sought. 

Certification of electrical equipment for use in hazardous areas is mandatory due to legislation that calls up AS/NZS2381.1. 

AS/NZS2381.1-2005, Clauses 2.3 and 2.4.2 require that electrical equipment installed in hazardous areas be protected by a suitable explosion protection technique complying with either:

·        the relevant Australian Standard; or

·        the relevant IEC Standard

as detailed in Table 2.1 of AS/NZS2381.1-2005.

The Standard further states that, “Certified apparatus shall be used as it provides the necessary assurance that apparatus meets the requirements of the appropriate Standard.”   Acceptable certification shall be covered by a certificate of conformity issued in accordance with:

·        the ANZEx scheme

·        the IECEx scheme

·        or another Type 5 scheme complying with ISO/IEC Guide 67, and meeting the requirements contained in AS/NZS2381.1 App. G.

Certificates under the AUSEx scheme are still valid.

Thus it is the certificate of conformity issued in accordance with the ANZEx, AUSEx or IECEx scheme, which determines the acceptability of electrical equipment for installation in hazardous areas. 

‘Other’ Ex Certification/Approval Systems

In circumstances when the user needs to use ATEX, FM, CSA, UL or other Ex equipment not certified to the ANZEx/AUSEx or IECEx schemes, the equipment and its installation must provide an equivalent level of safety to the ANZEx/AUSEx or IECEx schemes, and the user must obtain a Conformity Assessment document (CAD).  The CAD provides evidence that a certificate of conformity to an alternative standard can be demonstrated to provide an equivalent level of safety to AS/NZS or IEC Standards. This normally requires a comparison of the relevant standards and verification that testing has been conducted by a third party. The legal owner must provide justification for the use of the equipment and document the acceptance in the dossier.  In some instances, there may be additional legislated requirements for acceptance of apparatus certified to alternative standards.

Conclusion

The Australian Standards are important reference documents for personnel involved in any way with electrical equipment in Hazardous Areas.

Personnel who (a) where possible use Australian certified electrical equipment, (b) provide full documentation in the form of a verification dossier and (c) read, digest and utilise the standards and other Hazardous Area documentation to the best of their ability can be confident that their plant has very few, if any, electrical non-compliance problems.

References

[1] Garside: Intrinsically Safe Instrumentation - A Guide", published by Safety Technology Ltd, UK, 1982.
[2] H.G. Bass: "Intrinsic Safety", published by Quatermaine House Ltd, UK, 1984.
[3] SIRA Ltd: "Safety of Electrical Instrumentation in Potentially Explosive Atmospheres", unpublished course notes.
[4] ROSPA: "Electrical Installation in Flammable Atmospheres",published by ROSPA, UK, 1972.
[5] A.P.I. recommended practice RP500A, B and C.
A.G.A. Selection, Installation and Maintenance Guidelines for Ignition Systems Used in Class 1, Group D, Division 2 Locations on Internal Combustion, Spark Ignited Gas Engines. CPR-85-4-1
[6] Explosion Protection Technology website http://www.eptech.com.au 

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Other Useful Information

List of Current Hazardous Area and Electrical Equipment in Hazardous Areas IEC Standards - from IECEx.