Division of explosion-proof electrical equipment's protection class is based on the category of equipment used, the temperature group of explosive gases, and the type of explosion-proof design of the electrical equipment. Electrical equipment
Explosion-proof electrical equipment is divided into two categories: Category I for electrical equipment used in coal mine underground; Category II for electrical equipment used in locations other than mines, differentiated based on the Minimum Experimental Service Gap (MESG) or Minimum Ignition Current (MICR). Category II electrical equipment is further divided into three subcategories: IIA, IIB, and IIC.
The above four categories are mainly divided based on the potential spark quantities that could ignite under different operating conditions. China, as well as most countries and regions in Europe and around the world, categorizes explosive gases into these four hazard levels. The specific distinctions are as follows in the table below. Furthermore, based on the ignition temperature differences of explosive gases, the groups are further divided into T1, T2, T3, T4, T5, and T6, with the ignition temperature denoted as t (°C).