Page 28 - Electrical Installation in Hazardous Area

Introduction 7

The above method of legislating, while common in the UK, contrasts
significantly with legislation in countries such as Germany where legislation
tends to be more specific, giving much more detail in respect of the
precautions to be adopted. There is, however, little or no evidence available
to suggest that one or the other approach produces a better result as far
as safety is concerned. Thus, the UK approach has much to commend it
providing as it does maximum flexibility but, conversely, practitioners in
the UK must be fully competent to deal with the flexibility permitted.
In respect of dusts, a further regulation exists in the Factories Acts3 which
reflects the different nature of such materials, in that when a dust is released
it does not disperse as is the case with gases, vapours and mists but settles
and forms a layer which can be re-formed as a cloud at any time by any
sort of physical intervention. The regulation in question is Regulation 31(1)
which states:
When, in connection with any grinding, sieving, or other process
giving rise to dust, there may escape dust of such a character and
to such an extent as to be liable to explode on ignition, all practicable
steps shall be taken to prevent such an explosion by enclosure of the
plant used in the process, and by removal or prevention of accumu-
lation of any dust that may escape in spite of the enclosure, and by
exclusion or effective enclosure of possible sources of ignition.

While not specifically referring to electrical equipment, this regulation
includes it as a possible source of ignition and identifies the method of
protection as effective enclosure. This is possible as dust is nothing like as
penetrative as gas, vapour or mist and can effectively be excluded with
much less difficulty.
To underpin these regulations and give guidance, many British Standards
and Codes containing details of acceptable methods of compliance and
third-party certification facilities have been developed to give purchasers
of electrical equipment confidence. These certification schemes do not,
however, extend to installation and use.
In the past, when equipment construction Standards were limited and
lacked detail, a great deal of expertise was necessary within the certification
bodies as it was they who had to interpret what general statements within
Standards actually meant. Thus, it was not surprising that the certification
body in the UK was associated with the Health and Safety Executive and
the Safety in Mines Research Establishment organizations which made great
contributions to the more detailed technological base currently available.
Now, with much more detailed requirements, this relationship, while
remaining useful, is no longer necessary. The contribution of organizations
such as the Safety in Mines Research Establishment, and the Electrical
Research Association (now ERA Technology Ltd), the latter through its
industry sponsored project work, to the detail existing in current Standards
and Codes cannot however be overstated.
In addition to the above organizations, which were principally associated
with the construction of equipment, a great deal of work was done by