What is Hazardous Areas (HA) Classification?

What is Hazardous Areas (HA) Classification?

AS/NZS60079.14 Explosive atmospheres, Electrical installations design, selection and erection (the manual worshipped by all hazardous area engineers) defines a Hazardous Area as” an area in which an explosive atmosphere is present, or may be expected to be present, in quantities such as to require special precautions for the construction, installation and use of equipment.”.

Hazardous Areas can be found all manner of facilities, e.g. services stations, mine sites and breweries (yes that brewery you pop into on Friday arvo may have hazardous areas!). Gases like the propane used in your barbeque, and combustible dusts, such as flour and sugar are examples of common substances that can create explosive atmospheres under the right conditions.

HA Classification is the method of analysing an area where explosive atmospheres may occur, to facilitate the proper selection and installation of equipment to be used safely in the area, so as to avoid an explosion.
Areas are classified into zones based upon the frequency of the occurrence and duration of presence of an explosive atmosphere( i.e. how often and long the hazard is expected to exist for)

  • Zone 0: Area in which an explosive gas atmosphere is present continuously for long periods
  • Zone 1: Area in which an explosive gas atmosphere is likely to occur
  • Zone 2: Area in which an explosive gas atmosphere is not likely to occur in normal operation and, if it does occur, will persist for a short period only


Similar zone definitions exist for combustible dust areas – Zone 20, Zone 21 and Zone 22.
AS/NZS 3000 2018, The wiring rules, sets the requirements for electrical installations in hazardous areas. It’s the responsibility of the person in control of a facility to recognize that there are flammables present and to have the area classified, which must be performed by a competent person, like one of the ones on our team! If you do find yourself in need of a classification, or have other hazardous area related questions please give us a call – we’d love to hear from you.