process plant

Hazardous Areas Explained: Part 2 – Managing Hazardous Areas

Hazardous Areas can sometimes appear to be an area of ambiguity and mystery for some. 

Author: Brad Guy 

In Part 1 of our series, we defined a Hazardous Area. In Part 2, we’ll outline the requirements for managing Hazardous Areas. 


A Verification Dossier is defined, according to AS/NZS 60079.14:2017, as a: 

Set of documents showing the compliance of electrical equipment and installations. 

Therefore, all electrical equipment that is to be installed in a hazardous area will need to be manufactured to a certain standard along with the electrical design of the installation. 

Once a manufacturer develops a product, a sample of the equipment is to be sent to a Testing Laboratory (of which there are three acceptable Testing Laboratories in Australia) where they will put the equipment through a rigorous testing procedure. If the equipment satisfies these tests, results of the testing is then sent to the Certification Body that will Certify the equipment and issue a “Certificate of Conformity” for the equipment. 

Only equipment with a Certificate of Conformity under the ANZEx (previously AUS Ex) or IECEx scheme is suitable for installation in an Australian installation. Equipment certified to alternate foreign schemes may be accepted after a Conformity Assessment or Fitness for Purpose Assessment has been completed for that equipment for it to be installed on that site under certain conditions. 

All documentation in relation to the hazardous area needs to be retained and kept as a live document – this collection of documentation is called the Hazardous Area Verification Dossier. 

This can come in several different forms: hard copy, electronic copyor the software tools that have been created in alignment with AS/NZS 60079.17. The software can be used to retain information, carry out inspections and highlight non-conformances and upcoming inspections. The dossier must be accessible to all those on site working within or related to the hazardous area. 

The following is an example of the process to be carried out in relation to developing compliant hazardous areas along with documentation that needs to be retained and included in the Hazardous Area Verification Dossier to maintain compliance. 


When a hazardous area is present, or may be expected to be present, the first requirement is to complete a basic general arrangement design of the plant. From this design certain information is required to be able to perform a Hazardous Area Classification. 

  • General arrangement drawings 
  • Flammable gas, vapour 
  • Possible sources of release of vapours 

The hazardous area classification needs to be carried out to AS/NZS 60079.10.1 (latest version) by an electrical engineer with the required competency under the electrotechnical training package. 

UEENEEM052A – Classify Hazardous Areas – Gas Atmospheres 

The hazardous area classification is a study on the flammable gases and possible sources of release which will determine the “Zonal extents” as a Zone 0, 1 or 2 (for flammable gas atmospheres) or Zone 20, 21 or 22 (for combustible dust atmospheres). This restricts electrical equipment that can be installed in or enter these Zones (Permanent, portable, transportable and personal). 

The classification will also determine the gas group which determines how easily the gas can be ignited by “spark”. There are 3 gas groups IIA, IIB and IIC, (IIC being the most easily ignitable) or on the case of combustible dusts groups IIIA, IIIB or IIIC (IIIC being the most onerous). 

The classification will also determine temperature class which will determine how easily the gas can be ignited by “temperature”. There are 6 temperature classes T1, T2, T3, T4, T5 and T6, (T6 being the most easily ignitable) these are dependent on ambient temperatures. In the case of dust, the ignition temperatures of the dust is considered for both a layer of dust and a cloud of dust and given as a temperature. 

A flammable gas or combustible dust table will be created, giving properties of all flammable or combustible material found on site. 

A source of release table showing all possible sources of release and other information such as Grades of release and zonal extents explained. 

A Hazardous Area Classification Schedule is then created, which will include the previous tables mentioned in report form and hazardous area drawings drafted from information entered into the source of release table showing zonal extents gas or dust group and temperature class. These drawings should be available in both plan and elevation. 

As a plant increases in age some things change that may include 

  • Buildings erected or demolished 
  • Changes to the process 
  • Changes to chemicals used 

Any of these may alter the original classification and require a review from a competent person as mentioned previously. 

It is for this reason that it is recommended to have a review of the classification carried out on a regular basis to ensure safety, compliance and efficiency. 


Once the Hazardous Area Classification has been completed, the electrical design can be refined into suitable “certified” electrical equipment for that hazardous area. 

All electrical equipment is required to have certification from an accepted certification scheme as previously mentioned.  

Certification schemes accepted in Australia are: – 

  • IECEx (International Certification Scheme) 
  • ANZEx (Australia and New Zealand Certification Scheme) 
  • AUSEx (previous Australian Scheme Certification Scheme) 

An installation that has previously been designed and installed under the AUSEx scheme (prior to 2004 when the scheme started being phased out) remains compliant even if equipment needs to be changed out (like for like replacement only). If equipment fails and there is no identical equipment available and a replacement is required, it will be considered as a “New Installation” and needs to be treated as such. 

The hazardous area electrical design needs to be carried out to AS/NZS 60079.14 (latest version) by an electrical engineer holding the required competency under the electrotechnical training package 

UEENEEM057A – Design Explosion-Protected Electrical Systems and Installations – Gas Atmospheres 


Electrical equipment needs to be selected and installed according to the hazardous area electrical design. 

The hazardous area installation is an electrical installation and still needs to be installed and tested in accordance with AS/NZS 3000 as well as the latest edition of the Hazardous Area Standard AS/NZS 60079.14. 

The hazardous area installation needs to be installed by an electrician with an electrical licence for that State and holding the required competency under the electrotechnical training package 

UEENEEM024A – Install Explosion-Protected Equipment and Wiring Systems – Gas Atmospheres 


Maintenance for the hazardous area electrical installation needs to be carried out to the version of AS/NZS 60079.17 to which it was installed and carried out by an electrician with an electrical licence for that State and holding the required competency under the electrotechnical training package 

UEENEEM028A – Maintain Equipment in Hazardous Areas – Gas Atmospheres 


The hazardous area electrical installation needs to be tested to AS/NZS 60079.14 by an electrician with an electrical licence for that State and holding the required competency under the electrotechnical training package. 

UEENEEM039A – Conduct Testing of Hazardous Areas Installations – Gas Atmospheres 


Once the installation has been completed the hazardous area electrical installation is required to have an “Initial Detailed Inspection” carried out.  

Once the equipment is in service, ongoing periodic inspections are required to take place that can be completed as a visual inspection which is considered as a “hands in pockets” inspection, where the inspection is completed without tools or access equipment, or as a close grade inspection, which allows for the use of tools and access equipment and covers all aspects of a visual inspection with extra checks. 

All inspections need to be compliant to the version of AS/NZS 60079.17 to which the equipment was installed. 

The inspections are to be carried out by an electrician with an electrical licence for that State and holding the required competency under the electrotechnical training package. 

UEENEEM044A – Conduct Detailed Inspection of Hazardous Areas Installations – Gas Atmospheres 

All Victorian hazardous area installations require an inspection carried out by an electrician holding the “H” class endorsed Victorian electrical licence. 

NOTE: The hazardous area electrical inspector should be independent to the installation and maintenance personnel.  

The hazardous area electrical inspectors do not need to be from a different company. 


In the State of Queensland, the Electrical Safety Act requires that all “new” hazardous area installations within Queensland require a Hazardous Area Audit completed on the entire installation after the installation has been completed. 

The audit is required to be carried out prior to energisation of equipment and circuits within the hazardous area. 

The auditor needs to be accredited by the Department of Justice, Electrical Safety Office to carry out electrical hazardous area audits for that category: –  

  • Category A – flammable gases and liquids 
  • Category B – combustible dusts 
  • Category C – flammable gases, liquids and combustible dusts 

The audit will be carried out looking at classification, design, installation, maintenance strategies and information held in the verification dossier. 

A list of accredited hazardous area auditors can be found on the Department of Justice website. 


The information contained here is basic information only to give people a better understanding of requirements for hazardous areas. 

Every situation is different and needs to satisfy the following 

  • Relevant ACT’s and regulations 
  • Relevant standards 
  • Individual State requirements 
  • Site policy and procedures 

Some people find standards ambiguous or difficult to interpret but most in most instances the requirements and intent can be worked out without ambiguity.