Products for Explosion and Hazardous Environments
For various substances the explosive and spark ignition capability of a potentially explosive mixture are characteristic.
Vapors and gases are classified in groups.
The criteria for the subdivision are the maximum experimental safe gap and the minimum ignition current. These are determined under precisely defined test conditions for various vapors and gases.
Please refer to IEC60079-1A and IEC60079-3.
Consequently products classified IIC can also be used in IIB and IIA. The hazard increases from group IIA to IIC, therefore the requirements applicable to electrical equipment become more strict.