Page 20 - Electrical Installation in Hazardous Area

The technology of application of electrical equipment in explosive atmo-
spheres is very old, dating almost from the original application of electricity
to apparatus other than lighting. From its origins it has been developed in
most industrialized countries with the United Kingdom, Germany and the
United Sates of America being in the vanguard. As the world moves closer
together this technology has, like all others, been coordinated so that its
detail will be the same in all countries, principally to allow free marketing
around the world. This has led to more detailed standard requirements
particularly in the case of apparatus construction.
In the UK the considerable standardization of technology is defined in
more than 30 published standards (some national, some European and some
international). While this is basically good, in that it details what is neces-
sary and thus makes the achievement of safety easier in principle, it has
drawbacks in that there is considerable complication which can cause confu-
sion. Despite the longevity of the technology I can find no serious attempt
in the UK to produce a freely published volume, such as this, which brings
together the entire technology under one roof, as it were. This fact, together
with the pivotal role played by the UK in development through the British
Standards Institution, which brought together all the necessary expertise
to produce the necessary technical standards, the Safety in Mines Research
Establishment (now the Health and Safety Laboratory of the Health and
Safety Executive) and the Electrical Research Association (now ERA Tech-
nology), organizations that carried out much of the research work necessary
to permit the current standards to exist and the large contribution made by
UK industry, led me to write this volume.
The field can be divided into three facets:
1. The determination of the likelihood and the areas contaminated or likely
to be contaminated by explosive atmospheres produced by fuels such
as gas, vapour, mist, dust or a combination of these. This is still the
least researched of the areas of this technology, principally because there
are so many variations, in particular circumstances occurring in practical
locations.
2. The construction of electrical equipment so that it is unlikely to become
an ignition source. This has been heavily researched in many countries
because, unlike area classification, it is relatively specific and lends itself
more readily to specification.
3. The installation, operation, maintenance and inspection of electrical
equipment. This again is heavily influenced by the circumstances