Fundamental concerns with latest edition of IEC 60079-14
What is the issue?
In the latest edition of IEC 60079-14 the requirements regarding when a barrier gland should be employed were significantly changed. When dealing with Ex ‘d’ (flame proof) equipment, the previous criteria advocated the use of barrier glands depending on a number of conditions, which included the type of gaseous environment, the presence of internal ignition sources, the zonal location of the equipment and the internal volume of the equipment. The latest edition of the standard does away with this criteria and effectively states that barrier glands should be employed for cables less than three metres in length but are not needed for cables in excess of three metres.
Why is it important?
EEMUA’s primary concern is the potential safety implications; if (as according to the previous criteria) non barrier Ex ‘d’ glands are not sufficient for certain situations, the implications of a safety incident would likely be much greater than they would have otherwise been, with increased potential for secondary explosions and conflagration. There are also several secondary concerns. No scientific evidence to support the changes was ever presented, even when questioned by EEMUA’s Representative on the standards committee, and, perhaps more worryingly, despite the UK National Standards Body comments on the draft version, the new edition of the standard was progressed to publication with the response “noted but deferred to the next edition” from the authoring body. It is worth noting that the previous criteria were based on an Electrical Research Association (ERA) study conducted in the UK back in 1976.
What are the developments?
The UK’s implementation (BS EN 60079-14:2014) of the latest International version contains a formative annex notifying the reader over the concerns with the changes and advises users to continue to use the existing selection criteria. Whilst this provides a short term solution for UK users, it does not solve the larger issue or help other countries who will undoubtedly follow the international version by default.
What action did EEMUA take?
Acknowledging that technology and, in particular, cable manufacturing have moved on since the original study was conducted, EEMUA commissioned independent testing to better inform itself, and if necessary the relevant IEC maintenance team, on the potential implications of the latest edition. The aim was not simply to highlight potential flaws in the new criteria but also to reassess the previous findings.
What did the testing reveal?
The study results are now available and the EEMUA position statement is here. There are serious implications which should be taken into account for existing and future installations. In the light of these results EEMUA recommends a risk assessment for any installation which was done according to the IEC 60079-14:2013 criteria. A number of questions which may arise from this are answered here.
How is EEMUA engaged?
EEMUA’s Electrical Engineering Committee (ELC) has been following the issue and one of its members sits on the IEC TC31 Committee, which has responsibility for the IEC 60079 series of standards, and is also Chairman of the UK shadow committee BSI EXL/31/3. The Committee is also well represented on the impartiality committees of many of the UK certification bodies and plays a major role in the management of EEMUA Publications 186 A Practitioner's Handbook for potentially explosive atmospheres and 214 Toolbox guide which underpin the CompEx scheme for competency validation of personnel who undertake the installation, assembly, maintenance and inspection of electrical and other equipment used in hazardous areas.
For further information contact edward.kessler@eemua.org.
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