Page 163 - Electrical Installation in Hazardous Area

Area classification in areas which are not freely ventilated 129

Source of hazard

Ground

X = Distance wall/source of hazard (c 1.5 m)
Y = Distance source to ground (Z - Y =< 1.5 rn)
Z = Extent of hazardous area (unmodified)
a= 1.5Z-X
b = Distortion of hazardous area (densities greater than 1.3 only)
c = 0.75 Z (Densities less than 0.7 only)
Fig. 5.2 Effect of single walls within 1.5 rn of source of hazard

E = Extent of hazard taking account of wall proximity,
C = Distance source of hazard/wall end
a =E-C

Fig. 5.3 Typical two-wall effect (a)