
of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in
Chemical Process Areas.
The following Tables in NFPA documents can be referenced for information on specific
Materials Group designations and physical properties:
NFPA 70 National Electrical Code
Handbook, Article 500.6: Commentary Table 5.1
Selected Chemicals
TABLE 9.1 Class I and II Material Group designationsdcont’d
Group Materials
505.6 [15]
IIC Atmospheres containing acetylene, hydrogen, or flammable gas, flammable
liquid-produced vapor, or combustible liquid-produced vapor mixed with air that
may burn or explode, having either a maximum experimental safe gap ...