Use in Hazardous Environments
•
17
Classifications meeting the NEC 500
WAGO-I/O-SYSTEM 750
I/O Modules
Type “n” ignition protection additionally requires electrical components to be
marked with the following extended identification:
•
A – non spark generating (function modules without relay /without
switches)
•
AC – spark generating, contacts protected by seals (function modules with
relays / without switches)
•
L – limited energy (function modules with switch)
Further information
For more detailed information please refer to the national and/or international
standards, directives and regulations!
3.4 Classifications meeting the NEC 500
The following classifications according to NEC 500 (National Electric Code)
are valid for North America.
3.4.1 Divisions
The "Divisions" describe the degree of probability of whatever type of
dangerous situation occurring. Here the following assignments apply:
Explosion endangered areas due to combustible gases, fumes, mist and dust:
Division 1
Encompasses areas in which explosive atmospheres are to be expected
occasionally (> 10 h
≤
1000 h /year) as well as continuously and long-term
(> 1000 h /year).
Division 2
Encompasses areas in which explosive atmospheres can be expected rarely
and short-term (>0 h
≤
10 h /year).
3.4.2 Explosion protection groups
Electrical components for explosion endangered areas are subdivided in three
danger categories:
Class I (gases and fumes):
Group A (Acetylene)
Group B (Hydrogen)
Group C (Ethylene)
Group D (Methane)
Class II (dust):
Group E (Metal dust)
Group F (Coal dust)
Group G (Flour, starch and cereal dust)
Class III (fibers):
No sub-groups
