Page 240 - Electrical Installation in Hazardous Area

204 Electrical installations in hazardous areas

Luminaires (lighting fittings)

BS/EN 50014 (1993)l does not permit naked bulbs or tubes in lighting
fittings but requires them to be covered by a light transmitting cover.
In addition, it requires isolation before opening to relamp, for example,
unless the cover operates an interlock isolating the supplies to the lumi-
naire. Where this latter route is chosen, the isolating switch is required to
have its own recognized protection concept as it remains live when the
rest of the luminaire is isolated, and the spark on isolation together with
the contact separation after isolation needs to be secure. Its external termi-
nals also need to remain protected against interference in this state and it
must therefore be enclosed to IP20 (EN 60529 (1991)2) standard when the
transparent cover is removed.

8.1.7 Ex components

As an Ex component is not a complete item of apparatus it only needs
to satisfy the appropriate requirements of BS/EN 50014 (1993)*. These
vary according to the type of component but the Standard identifies the
following as not being applicable to any components: First, the requirements
for surface temperature classification. (It must, however, have a maximum
operating temperature defined); and Second, the definition of the delay time
necessary to ensure that any residual charge or high temperature remaining
after isolation is dissipated before opening.
The other clauses of the Standard apply as appropriate (i.e., the Clauses
relating to an apparatus enclosure only apply if the component is an empty
enclosure).

8.1.8 Marking requirements

The marking requirements of the Standard include identification of the
manufacturer, the certification Code and other relevant information. While
a certification mark is not a requirement, unless the apparatus is certified,
there are several requirements for intervention of ‘the test station’ in the
marking clause. This means that it is normal to have certification and such
a mark will normally be present. Typical of the certification coding are the
following.
EEx: The first ’E’ shows compliance with this Standard and one of the
subsequent protection concept Standards, and the subsequent ’Ex’ identifies
the equipment as explosion protected. Although the ’Ex’ appears on all
explosion protected apparatus the first ’E’ only appears on that protected
to BS/EN 50014 (1993), its predecessor and its subsidiary protection concept
Standards.
d: The symbol for the protection concept follows the ’EEx’, the one shown
here being for flameproof enclosure. This symbol will vary depending on
the protection concept used as follows: