6 • Application in Explosive Environments
Classifications meeting the NEC 500
Ex-1.4 Classifications meeting the NEC 500
The following classifications according to NEC 500 (National Electric Code) are valid for North America.
Ex-1.4.1 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).
Ex-1.4.2 Explosion protection groups
Electrical components for explosion endangered areas are subdivided in three danger categories:
Class I (gases and fumes): |
Group A (Acetylene) |
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Group B (Hydrogen) |
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Group C (Ethylene) |
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Group D (Methane) |
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Class II (dust): |
Group E (Metal dust) |
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Group F (Coal dust) |
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Group G (Flour, starch and cereal dust) |
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Class III (fibers): |
No sub-groups |
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WAGO-I/O-SYSTEM 750
Modular I/O-System
