Electrical equipment for explosive gas atmosphere is divided into:

Class I: electrical equipment used in coal mines;

Class II: Electrical equipment used in explosive gas atmospheres other than coal mines;

Class II flameproof "d" and intrinsically safe "i" electrical equipment are divided into IIA, IIB, and IIC;

Electrical equipment for combustible dust environment is divided into:

Type A dust-tight equipment;

Type B dust-tight equipment;

Type A dustproof equipment;

Type B dustproof equipment.

Gas group

The explosive transmission capability of an explosive gas mixture indicates the degree of explosion risk. The greater the explosive transmission capability of an explosive mixture, the higher its risk. The explosion transfer capacity of explosive mixtures can be expressed by the maximum test safety clearance. At the same time, the ease with which explosive gases, liquid vapors and mists are ignited also marks the degree of explosion hazard, which is expressed by the minimum ignition current ratio. Class II flameproof electrical equipment or intrinsically safe electrical equipment is further divided into IIA, IIB and IIC according to the maximum test safety gap or minimum ignition current ratio applicable to explosive gas mixtures. As shown in the following table: