There are two independent classification systems as described in the NEC. One system, found in Article 500 of the NEC, the other is found in Articles 505 and 506 of the NEC.
Classification System that found in Article 500:
- Article 500 divides all hazardous (classified) locations into Classes (I, II & III), Divisions (1 & 2) and Groups (A, B, C, D, E, F & G).
Classification System that found in Articles 505 & 506:
- Article 505 divides locations having gases and vapors into Class I, Zones (0, 1 & 2) and Gas Groups (IIA, IIB & IIC).
- Article 506 divides locations having dusts, fibers or flyings into Zones (20, 21 & 22).
[Note] NEC - National Electrical Code of USA
GCS Safety Team