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General requirements for explosion protected apparatus 1 79

this approach has been shown to have significant drawbacks, in that any
change to the general requirements Standard automatically impinges upon
the particular protection concept Standards which are written by different
European committees, comprising different sets of people to those involved
in the writing of the general requirements Standard. To overcome this,
particular protection concept Standards specify a particular issue of the
general requirements Standard, but this means that, as the particular protec-
tion concept Standards are written in different time frames, it is necessary
to have more than one issue of the general requirements Standard valid
at any one time. Unless one is very careful, confusion can result. While
the situation is less than perfect, it is unlikely to change and whenever a
particular protection concept is addressed, it is necessary to ensure that it is
addressed with the appropriate issue of the general requirements Standard.
The latest issue of the general requirements Standard is BS/EN 50014
(second edition) (1993)l which applies to all of the protection concepts with
the exception of Exm (BS 5501, Part 8 (1988) - EN 50028 (1987) at present.
Its predecessor which applies to Ex m was BS 5501, Part 1 (1977) - EN 50014
(1977), first edition. A further complication is the fact that both of these Stan-
dards have been the subject of amendments issued after the publication of
the Standards (seven in the case of BS 5501 part 1 (1977) and one in the case
of BS/EN 50014 (1993)l. In general terms, amendments are considered to
be part of the standard and thus will apply to all of the protection concept
Standards from the date of amendment issue, unless these latter Standards
are themselves amended to exclude the amendment to the general require-
ments Standard. To simplify the situation, therefore, the second edition of
the Standard (BS/EN 50014 (1993)l, including amendment 1) will form the
basis of the content of this chapter and differences between it and the first
edition (BS 5501, part 1 (1977), including amendments 1 to 7) will be high-
lighted to cover the situation until Directive 76/117/EEC is amended, as
previously discussed.

8.1 BS/EN 5001 4 (1 993) (including amendment 1 (1 994))

It is better to deal with the amendment to this Standard first to avoid any
confusion. It may appear that the necessity to amend a Standard so soon
after its publication is worrying, but the amendment was issued only to the
English text of the Standard which omitted the limitation of validity of the
Standard to the second editions of the protection concept standards only.
(All European Standards are written in three languages, English, French
and German and in this case the English language text omitted a paragraph
present in the French and German texts). It is worthy of note here that EN
Standards may appear in other languages but those are national translations
and in any dispute as to the meaning of the Standards the English, French
and German texts must be referred to for clarification.
BS/EN 50014 (1993)l deals with those matters common to more than one
of the protection concepts. Some of its content may not be appropriate to a