Flammable Atmospheres Directives and EN50 Standards

[/G=Nick/S=Ludlam/O=FMEO/OU1=Norwood,_MA/OU2=FMEO-FMRC_Approvals]

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    Dear Mr Benjamin
    
    You have chosen a complicated subject to investigate, I will try to 
    give you a brief answer.
    
    Directives
    
    The original directive(76/117EEC) was issued in 1976 and made no 
    reference to any standards, but did set out a series of guidelines 
    which had to be met in order for the numerous certification 
    organisations (or Nominated Bodies) to issue certificates which would 
    be valid through out the European Community.  In 1977 the majority of 
    the EN 50 0XX series of standards which dealt with Electrical Apparatus 
    for potentially explosive atmospheres were published, and these were 
    incorporated into the European Directive by an amending directive 
    (79/196EEC).  The EN standards were based on the equivalent IEC 
    standards. Subsequent amendments to the standards have been included in 
    the European directive by a number of amending directives.
    
    In 1994 another Directive was issued (94/9EC). This will ultimately 
    supercede 76/117EEC and its amending directives, but this will not 
    happen until June 2003 and in the meantime the two directives will run 
    in parallel.  Directive 94/9EC is also known as the ATEX Directive.
    
    Standards
    
    The first edition of the standards were published in 1977, EN 50 039 
    was published in 1981. The three standards you refer to cover the 
    general requirements (014), intrinsic safety apparatus (020), and 
    intrinsically safe systems (039). With the exeption of EN 50 039, two 
    versions of these standards exist, those published in 1977, and a newer 
    set published after 1994. If you were looking for a piece of apparatus 
    to be certified by a European certification body then the 1977 series 
    of standards would be used as these are the only ones listed in the 
    Directives. (The second editions are due to be listed but everyone is 
    waiting for the European Commision to do this)
    
    
    General
    
    I work for Factory Mutual Research Corporation based in Massachussetts, 
    but previously worked for over 12 years at one of the Notified Bodies 
    in the United Kingdom. It really can seem to be complicated and is 
    difficult to give a concise answer especially to such a broad question.  
    If you wish I am willing to discuss this subject, my 'phonee number is 
    (617) 255 4847  

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