Technical data

318 • Use in Hazardous Environments
Classification Meeting CENELEC and IEC
WAGO-I/O-SYSTEM 750
BACnet/IP Controller
9.3.2 Device Group
In addition, the electrical components for explosive areas are subdivided into
two device groups:
Device Group I: Device group I includes electrical components for use
in below-ground mining operations as well as above-
ground systems potentially endangered by mine gas
and/or combustible dust.
Device Group II: Device Group II includes electrical components for
use in all other explosive environments. This device
group is further subdivided by pertinent combustible
gases in the environment.
Subdivision IIA, IIB and IIC takes into account that
different materials/substances/gases have various
ignition energy characteristic values. For this reason
the three sub-groups are assigned representative types
of gases:
• IIA – Propane
• IIB – Ethylene
• IIC – Hydrogen
Tab. 9-1: Minimal ignition energy of representative types of gases
Minimal Ignition Energy of Representative Types of Gases
Explosion group I IIA IIB IIC
Gases Methane Propane Ethylene Hydrogen
Ignition energy (µJ) 280 250 82 16
Hydrogen being commonly encountered in chemical plants, frequently the
explosion device group IIC is requested for maximum safety.