Page 207 - Electrical Installation in Hazardous Area

Design philosophy for electrical apparatus for explosive atmospheres 1 71

in a relatively general form and it is intended to identify the harmonized
standards (EN’S) as a method of satisfying the essential requirements, by
their approval by publication in the European Journal7. Unfortunately, it
has been realized that the second editions of these current Standards do
not necessarily satisfy the essential requirements and the Standards writing
body, the Centre Europeen de Normalization Electrique (CENELEC), has
been remitted to produce third editions which do in general, in 1997. This
means that the new Directive5 cannot be practically introduced until some
time in 1997, and in the meantime the older Directive2 will remain the only
vehicle by which the Distinctive Community Mark can be awarded. Unfor-
tunately, this Directive still refers to the first editions of the harmonized
Standards and the second editions, now current, will not permit the use of
the mark. Urgent action is being taken to introduce the second editions of
the harmonized Standards into 76/117/EEC2 but until that time certification
in accordance with that Directive will be in line with the first editions.
While this seems to be a problem, it is not really, since the second
editions do not vary widely from the first, and most equipment manu-
facturers are ensuring that their equipment will comply with both until
the new Directive5 comes into force . When this Directive5 is enacted the
third editions of the harmonized Standards will exist, and any equipment
certified after that will comply to the new provisions.

7.5.1 Zone 0 and/or Zone I compatible apparatus for gases,
vapours and mists

As already stated, there is a long world-wide history of utilizing only third-
party certified equipment in Zone 0 and 1 and in some countries this is
required by law. At the moment this is not the case in the UK, but the
new Explosive Atmosphere Directive5 from the EU will effectively ensure
this by requiring that all equipment marketed in the EU complies with it
(the Directive itself requiring third-party type certification as a minimum).
While this will cause some restriction in the UK the impact will not be
great, as industry in the UK has historically used only third-party certified
equipment by choice. Therefore, subject to the resolution of the difficulties
already identified in this chapter, the situation will not change greatly.
What this historic situation has led to is a very high degree of detailed
construction Standards which have become more and more international
due to the international level of operation of the industry which needs
the equipment. The current situation is that the Standards for electrical
equipment intended generally for Zone 0 or Zone 1 (or both) are fully
harmonized European Standards, and within the next 10 years will become
fully harmonized International Standards. There are, however, historic
national and European Standards which address this area and equipment is
still available complying with these Standards. There is no suggestion that,
in general, such equipment is not still safely usable in many circumstances,
and the titles of those Standards are referred to in Chapters 8 to 15. Many of