A hazardous area is one in which an explosive atmosphere is present, or may be expected to be present, in a quantity that necessitates special precautions for the construction, installation and use of all electrical equipment, both freestanding and fixed.
This includes areas where flammable goods or combustible dusts are stored as well as when they may generate a flammable or combustible atmosphere, for example during handling, production or under certain conditions.
There are a number of key elements that need to be understood:
- The assessment of the hazard flammable zone type
- The amount of vapour/dust produced
- Gas grouping
- The lower explosive limit of the generated vapour/dust
- The level of ventilation under all conditions
- The temperature class of the zone (for the selection of appropriate electrical fittings)
Electrical companies will only ‘turn on’ power to a building if all defined hazardous areas have been identified and appropriate documentation presented, such as a ‘Hazardous Area Verification Dossier’. If electrical works are required to be carried out in a defined hazardous location, such as an inspection, maintenance or replacement of electrical equipment, the occupier (owner) must make available a Hazardous Area Dossier to the worker at the time of inspection or works.
AS/NZS 60079.17 and AS/NZS 60079.14, both state in part that, ‘It is necessary to ensure that any installation complies with the appropriate documents, this standard and any other requirements specific to the plant on which the installation takes place.’ A verification dossier is one such document which details compliance and has to be kept on the premises at all times. It is the responsibility of the occupier to ensure that the relevant information is produced, but it is recognised that the preparation of the document may be delegated to others.