Page 39 - Electrical Installation in Hazardous Area

18 Electrical installations in hazardous areas

Table 1.2 Relationship of temperature classi-
fication systems
~~ ~~~
European and UK German USA

T1 G1 T1
T2 G2 T2
- - T2A (280°C)
- - T2B (260°C)
- - T2C (230°C)
- - T2D (215°C)
T3 G3 T3
- - T3A (180 "C)
- - T3B (165°C)
- - T3C (160°C)
T4 G4 T4
- - T4A (120 "C)
T5 G5 T5
T6 - T6

Note: Prior to the introduction of a separate temperature
classification system in the USA temperature classifica-
tion was associated with the grouping system as follows:
Groups A, B and D were given a maximum temperature
of 280°C; Group C was given a maximum temperature
of 180°C; Groups E and F were given a temperature of
200 "C; and Group G a temperature of 165°C.

1.8 The future of certification

As has been stated, the situation in regard to certification is significantly
affected by the 1990 Directive" which came into force early in 1996.
While this will initially rely on European Standards referred to in the
European Journal12 it is certain that the breadth of the essential requirements
contained within the Directive" will ultimately be used. As these essential
requirements are couched in much more general terms than the Standards,
then the approved bodies will have to revert to the expert interpretation of
more general requirements much as they did before the advent of the more
detailed Standards. The level of expertise of the certification bodies will once
again, therefore, become of paramount importance. To this end the HOTL
grouping will assume a much greater sigruficance and it is unlikely that it
will contain sufficient expertise without introducing industrial expertise into
it. How this can be done without making it as cumbersome as a Standards-
making body will no doubt become a matter for considerable debate in the
not too distant future.
The inclusion of non-electrical equipment for which the level of detailed
standardization in this area is much lower will mean that the problem of
certification to the requirements contained in the new Directive" will be
apparent much sooner. Not only will the currently approved bodies not