This Standard specifies requirements for the design, construction and testing of pressurized rooms or pressurized enclosures, type of protection 'p', intended for use in Class I, Zone 1 and Zone 2 or Class II explosive atmospheres. While this standard covers enclosures with an internal release of flammable gas or vapour, it does not cover rooms with such a release, e.g. analyser houses nor rooms or enclosures with an internal release of combustible dust.The requirements contained in this Standard are supplementary to those in AS 2380.1.NOTES:1 The classification of explosive atmospheres, termed hazardous areas, is dealt with in AS 2430. Further guidance may be obtained from Handbook SAA HB13.2 Equipment with large areas which are subjected to pressures in excess of 1 kPa (e.g. sheet metal switchboard enclosures) may require approval from the relevant authority responsible for pressure vessel legislation in the State or Territory in which the enclosure is to be installed.3 Rooms in which there is an internal release of flammable gas or vapour e.g. analyser houses are covered by IEC 79-16.4 Areas not covered by this standard may be treated by protection by ventilation in accordance with AS 1482.5 To minimise the risk of failure of an enclosure due to rupturing arc faults safeguarding against potential fault currents of an installation, especially where levels exceed 6 KA, should be provided.