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Apparatus classification

The ATEX 94/9/EC European Directive classifies equipment into three categories, with differing protection levels, related to the protection guaranteed.

EQUIPMENT CATEGORIES
PROTECTION
LEVEL
guaranteed by
the equipment
Category
MINESURFACE
CategoryGAS
Category
COMBUSTIBLE
DUST
Category
Very highM11G1D
HighM22G2D
Normalnot provided for3G3D

Note: Equipment of higher categories can also be installed instead of those of a lower category.

Enclosure groups

The standards classify electrical equipment into two groups.

Group I: electric apparatus to be installed in mines or galleries susceptible to fire damp or coal dust.

Group II: electric apparatus to be installed in surface plants susceptible to other explosive atmospheres.

The enclosures for equipment intended for use on the surface, providing “d” protection (flameproof), are in turn broken down into three sub-groups, in relation to the inflammable substances for which they are suitable: Group IIA, Group IIB, Group IIC.

A motor that belongs to a certain enclosure group is also suitable for lower enclosure groups: a motor in group IIB is also suitable for group IIA; a motor in group IIC is also suitable for group IIA and IIB.