Examples of the assignment of gases and vapours to the respective temperature classes and explosion sub-groups:

Dusts

Explosion sub-group - Conductivity of the dust
The IEC 61241-2-2 contains the test method for determining the specific electrical resistance of dust. The various types of dust are divided into 3 sub-groups according to this resistance:
IIIA | combustible flyings |
IIIB | non-conductive combustible dust, specific electrical resistance > 10³ Ω |
IIIC | conductive combustible dust, specific electrical resistance < 10³ Ω |