There is currently a key difference between the current IEC 60079-14: 2013 Standard and previous versions of BS EN 60079 -14:2008 & IEC 60079- 14: 2007 for use of electrical equipment in potentially explosive atmospheres in that the IEC Standard currently allows the Duty Holder to use a 'standard' Ex certified flameproof gland as opposed to a Ex certified 'barrier gland' without the requirement to apply the previous flowchart used in the British Standard which identified glanding requirements based on gas group / zone / enclosure size. There is evidence that this approach creates a fire and explosion risk and this Notice provides Duty Holders with information on what action to take.

The current International Standard, IEC 60079-14: 2013 Standard allows Duty Holders to use a 'standard' Ex certified flameproof gland as opposed to a Ex certified 'barrier gland' without the requirement to apply the previous flowchart used in the British Standard which identified the glanding requirements based on gas group / zone / enclosure size, provided that the Duty Holder uses:

b) Cables and glands meeting all of the following:

There is credible independent evidence that this approach poses a risk of fire propagation through the cable sheath (after multiple ignitions) and therefore such a scenario may pose an ignition risk if the new IEC Standard is applied by Duty Holders, ie no barrier gland is used.

The 2014 version of BS EN 60079-14 does mirror the IEC Standard in respect of the above clause and requirements in the 'Normative' body of the Standard, however this version also contains a National Annex (NA) (see p138 onwards) that acknowledges the British Standards Institution's (BSI) concerns over the application of the IEC Standard to the use of barrier glands (see below). Reference to this National Annex is also clearly stated in the 'National foreword' of the British Standard:

At the moment this issue is being escalated by the BSI Technical Committee and the British Standard is also clear (although this National Annex section is 'Informative') that Duty Holders should continue to consult the existing flowchart (ie the selection chart - included in the NA annex Figure 1) to determine if a flameproof 'barrier' gland should be used.

HSE recognises the risks identified by the BSI Technical Committee and also has further independent 3rd party evidence that supports the BSI's conclusions.

In order to ensure that this risk is suitably controlled, the HSE has defined the 'Informative' National Annex of BS EN 60079-14: 2014 as an 'Established Standard' (see http://www.hse.gov.uk/enforce/emm.pdf ) as it is considered to be a "published or commonly known standard of performance interpreted by HSE as a level of performance needed to meet a general or qualified duty under health and safety".

Duty Holders should therefore apply the Informative National Annex of BS EN 60079-14: 2014 as Relevant Good Practice when assessing the requirements for fitting a barrier gland to electrical equipment in potentially explosive atmospheres.

Control of Major Accident Hazards Regulations (COMAH) 2015 Dangerous Substances and Explosive Atmospheres Regulations 2002 BS EN 60079 -14: 2014 (National Annex)

Contact the HSE's CEMHD Electrical, Control and Instrumentation team for further information on the subject or visit http://www.hse.gov.uk/eci/index.htm

This Safety Notice should be circulated to all relevant Duty Holders / Employees that are involved in the design, selection, installation, inspection and maintenance of electrical equipment in potentially explosive atmospheres.

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