AS/NZS 1826:2008

This Standard gives the specific requirements for the construction, assessment and testing and marking of electrical equipment, parts of electrical equipment and Ex components with the type of protection known as special protection ‘s’.This Standard only applies for special protection as applied to electrical equipment, parts of electrical equipment and Ex components (hereinafter always referred to as ‘s’ equipment) applicable to Group I, Group II and Group III as defined in AS/NZS 60079.0.This Standard supplements the general requirements in AS/NZS 60079.0.It is applicable to equipment intended for equipment protection levels (EPLs) ‘Ma’, ‘Ga’, ‘Da’, ‘Mb’, ‘Gb’, ‘Db’, ‘Gc’ and ‘Dc’ as defined in AS/NZS 60079.0. The equipment has to be designed, tested and marked according to the equipment protection level for which it is assigned.This Standard is not applicable to equipment or any parts of equipment where one or more types of protection as described in AS/NZS 60079 series, or to combinations of types of protection as described in AS/NZS 60079.26, can be applied.Where the explosion-protection is achieved by using an established type of explosion-protection technique, then verification of the equipment has to be based on the requirements of that part of the AS/NZS 60079 series applicable to such technique. Any variations from these requirements have to be specified and agreed between the manufacturer and independent verifier.This Standard is also intended to apply to equipment operating in explosive gas atmospheres or explosive dust atmospheres, under conditions other than the atmospheric conditions given in AS/NZS 60079.0. However, additional assessment and testing related specifically to the intended conditions of use will be required. This is particularly important when the types of explosion-protection techniques known as ‘flameproof enclosure’ (AS/NZS 60079.1) and ‘intrinsic safety’ (AS/NZS 60079.11) are applied. Such conditions might include hypobaric, hyperbaric and oxygen enriched atmospheres. NOTES:1 This Standard is not intended to apply as a last resort in the event that equipment fails compliance to the AS/NZS 60079 series. Ex ’s’ is only considered where design options are limited for technical, operational or functional reasons2 This may mean that modification of the design will be necessary to meet the requirements of the established explosion-protection techniques. 3 This Standard may be used where equipment needs to be used at a higher EPL than the underlying protection techniques allow. If this occurs additional control measures and/or additional design and test requirements need to be applied. 4 Parts of equipment that can be designed and tested to standardized explosion-protection techniques should be so designed. Only those parts that achieve safety through alternative controls should be considered for Ex ’s’. An example where technical, operational or functional limitations preclude recognized explosion-protection techniques being used, is in gas detectors for EPL ‘Ma’ or ‘Ga’, using heated filaments. The major part of the equipment can comply with Ex ’ia’, but in order to function, the filaments, which are ignition sources, have to be exposed directly to the gas. The gas has to get to the filaments by diffusion or aspiration. In either case, the protection is to contain flame or explosion. This protection can only consist of one or more porous metal screens. These are permitted in Ex ’d’, but that explosion-protection technique is limited to EPL ‘Mb’ or ‘Gb’. A second layer of a different type of protection (as permitted in AS/NZS 60079.26 for EPL ‘Ga’), is not physically possible, as it cannot permit free access of gas. Ex ’s’ is therefore the only solution for this part of the gas detector.

Originated as AS 1826-1976.Previous edition 1983.Revised and redesignated AS/NZS 1826(Int):2006.Fourth edition 2008. Originated as AS 1826-1976. Previous edition AS/NZS 1826(Int):2006. Fourth edition 2008.