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Guide · Hazardous areas
EEHA explained: a plain-English guide to hazardous area electrical work
Zones, AS/NZS 60079, Ex equipment and the verification dossier, and what a compliant hazardous area project looks like.
If your site handles flammable gases, liquids or combustible dusts, the electrical equipment in those areas has to be designed and installed so it can't become the ignition source for an explosion. That is EEHA, Electrical Equipment in Hazardous Areas, and in Australia it is governed by the AS/NZS 60079 series. This guide explains how it works in plain English.
Where hazardous areas turn up
Hazardous areas aren't just in mines and refineries. In the Riverina and regional industry we regularly see them in:
- Food and beverage: distilleries and spirits handling, ethanol and solvent stores
- Grain, flour, sugar and feed: silos, elevators, mills, bagging and dust collection
- Pellet and biomass plants: wood and biomass dust around hammer mills, conveyors and pellet presses
- Fuel and gas: diesel and petrol storage, LPG and natural gas installations
- Waste and water: biogas, landfill gas and digester areas
- Workshops: paint booths and solvent cleaning areas
The legal side
Under the WHS Regulations, a business must manage the risks from an ignition source in a hazardous atmosphere, and must make sure ignition sources are not introduced into hazardous areas where hazardous chemicals are stored or handled. The AS/NZS 60079 standards are how that is done for electrical equipment, and electrical safety regulators expect hazardous area work to follow them.
The key standards
- Area classification: AS/NZS IEC 60079.10.1 for gases and vapours, and AS/NZS 60079.10.2 for combustible dusts
- Design, selection and installation: AS/NZS 60079.14
- Inspection and maintenance: AS/NZS 60079.17
- Repair and overhaul of Ex equipment: AS/NZS 3800
- Intrinsically safe systems: AS/NZS 60079.25
Zones in plain English
Area classification divides a site into zones based on how likely an explosive atmosphere is to be present:
- Zone 0 / Zone 20: present continuously or for long periods, such as inside a tank or a dust collector
- Zone 1 / Zone 21: likely to occur occasionally in normal operation, such as around filling and emptying points
- Zone 2 / Zone 22: not likely in normal operation, and only briefly if it does occur, such as around flanges, valves and leaks
Each zone needs equipment with a matching Equipment Protection Level: Ga, Gb or Gc for gas, and Da, Db or Dc for dust. Equipment rated for a more hazardous zone can be used in a less hazardous one, but never the other way round. Equipment must also suit the gas or dust group and have a temperature class below the ignition temperature of the material present.
How a hazardous area project runs
- Classify the area. Identify every flammable material and release source, then define the zones and their extent on zone drawings.
- Design the installation. Select certified Ex equipment and protection methods (flameproof, increased safety, intrinsic safety, pressurisation, dust protection by enclosure), and design cabling, glands, earthing and isolation to AS/NZS 60079.14.
- Keep equipment out where possible. The simplest Ex equipment is the equipment you don't need: control panels, drives and PLCs are located outside the hazardous area wherever practical.
- Install with competent people. Hazardous area work must be done by electricians with EEHA competencies.
- Inspect before energising. A detailed initial inspection confirms every item is correctly selected and installed.
- Hand over the verification dossier. Classification, drawings, certificates and inspection records, kept on site and updated whenever things change.
- Maintain it. Periodic inspections to AS/NZS 60079.17, and Ex equipment repaired only to AS/NZS 3800.
Common problems we find
- No area classification, or one that no longer matches the plant after changes
- Standard lights, motors, GPOs or junction boxes installed in a classified zone
- Ex equipment with the wrong gas group or temperature class for the material present
- Incorrect or missing cable glands, open entries and unused entries without certified stopping plugs
- Dust build-up on equipment in grain, flour and biomass areas
- No verification dossier, or one that hasn't been updated in years
How AMC helps
AMC delivers hazardous area electrical work from classification through to handover. Our engineers design installations to AS/NZS 60079.14, select certified Ex equipment and keep as much as possible outside the hazardous zones. Panels are built in our Griffith workshop, installation is done by EEHA-competent electricians, and every job finishes with an initial inspection and a complete verification dossier. We work across food and beverage, grain and agriculture, biomass, water and waste, in the Riverina and Australia-wide.
This guide is general information to help you understand hazardous area requirements. It is not legal advice, and the requirements for a specific site depend on its area classification.
FAQs
Common questions about hazardous areas
What does EEHA stand for?
Electrical Equipment in Hazardous Areas. It covers the classification, design, installation, inspection and maintenance of electrical equipment in places where flammable gas, vapour or combustible dust could form an explosive atmosphere.
Do I have a hazardous area?
If your site stores or handles flammable liquids, gases or combustible dusts, you may. Common examples are fuel and LPG storage, spirits and ethanol, solvents and paint, biogas and landfill gas, grain, flour, sugar, feed and wood dust. A hazardous area classification tells you for certain, and where the zones are.
What is the difference between Zone 1 and Zone 2?
Zone 1 is where an explosive gas atmosphere is likely to occur occasionally in normal operation. Zone 2 is where it is not likely in normal operation and, if it does occur, only for a short time. Dust areas use Zones 20, 21 and 22 on the same basis.
Can I use standard electrical equipment in a Zone 2 area?
No. Equipment in any hazardous zone must be certified for that zone, gas or dust group and temperature class, and installed to AS/NZS 60079.14. Standard equipment can only be used outside the classified area.
What is a hazardous area verification dossier?
It is the set of records that proves your hazardous area installation complies: the area classification and zone drawings, equipment certificates, as-installed drawings, and inspection and maintenance records. It must be kept current and available on site.
How often do hazardous area installations need inspecting?
An initial detailed inspection is required before the installation is put into service, then periodic inspections under AS/NZS 60079.17. The interval depends on the equipment, environment and risk, and is typically no more than a few years between inspections.
Can AMC do the whole job?
Yes. We carry out or coordinate the area classification, design and select Ex equipment, build panels in our Griffith workshop, install with EEHA-competent electricians, complete the initial inspection and hand over the verification dossier.
Next step
Got a plant, machine or board that needs sorting?
Send us the scope, drawings or a few photos. An engineer reads every request and comes back within one business day with next steps and a clear, upfront price.