Quatech INTERBUS S manual Ex-1.4 Classifications meeting the NEC, Ex-1.4.1 Divisions

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)
	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

WAGO-I/O-SYSTEM 750 Modular I/O-System