218 • Use in Hazardous EnvironmentsWAGO-I/O-SYSTEM 750ETHERNET TCP/IPType “n” ignition protection additionally requires electrical components to bemarked with the following extended identification:A – non spark generating (function modules without relay /without switches)AC – spark generating, contacts protected by seals (function modules withrelays / without switches)L – limited energy (function modules with switch)Further informationFor more detailed information please refer to the national and/or internationalstandards, directives and regulations!7.4 Classifications meeting the NEC 500The following classifications according to NEC 500 (National Electric Code)are valid for North America.7.4.1 DivisionsThe "Divisions" describe the degree of probability of whatever type ofdangerous 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 expectedoccasionally (> 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 rarelyand short-term (>0 h ≤ 10 h /year).7.4.2 Explosion protection groupsElectrical components for explosion endangered areas are subdivided in threedanger 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
