Page 65 - Electrical Installation in Hazardous Area

Area classification 41

grounds of toxicity is not countenanced. The safety officer will also have the
overall responsibility for safety on the site where the process is eventually
located and it is therefore essential that he or she finds the results of the
area classification acceptable.
Electriculhzstrument engineer; although in the future area classification will
form the basis for the selection of all equipment, both mechanical and elec-
trical, it has only been the latter which has historically been formally asso-
ciated with the technique. Therefore, the role of the electrical/instrument
engineer has been, and will continue to be, to advise on the limitations of
electrical installation in classified areas and the reliability of electrical installa-
tions, as these can have an effect upon the possibility of release of flammable
material and its severity. As almost all process activities are effected by elec-
trical drives, illuminated by electric light and monitored by electrical instru-
mentation, the area classification, in defining what electrical installations are
possible, has a fundamental effect on the process and its design.
Site representative; any process or activity has to be carried out on a
particular site. It is necessary, therefore, to have a representative of site
management on the group to identify particular facets on the chosen site
during the design process so that final construction and use will be trouble
free. This is no less true of the area classification exercise.

2.9 Results of area classification and frequency of repeats
The area classification exercise carried out by the above group should, as
already identified be commenced as soon as possible during the design
process and continually refined until construction is complete. Its results
should be recorded on LEAC sheets and form a dossier, together with all
necessary supporting information which should be accessible to or given
into the custody of those who have to manage the operation of the process.
As soon as possible after commencement of operation, and certainly within
one year, the area classification should be reviewed in relation to practical
operating experience and after that regular reviews should be undertaken.
The frequency of such reviews should be determined on the basis of expe-
rience but in no case should the period between reviews be more than two
years. The period to be used will depend upon operating experience and, if
it is found that each review results in si&cant area classification changes
then the review period should be shortened. Likewise, if no changes are
found the period can be elongated up to the two-year limit. Any change
in process or equipment on the site should result in an immediate area
classification review.

References

1 BS/CP 1003 Electrical Apparatus and Associated Equipment for use in
Explosive Atmospheres other than Mining Applications:
Part 1 (1964). Choice Installation and Maintenance of