The classification of explosion-proof levels for electrical equipment is based on the type of equipment used, the temperature group of explosive gases, and the explosion-proof type of the electrical equipment. Electrical equipment
Explosion-proof electrical equipment is divided into two categories: Class I is for electrical equipment used in coal mine underground; Class II is for electrical equipment used in places other than mines, distinguished by either the Minimum Experimental Short Circuit Gap (MESG) or the Minimum Ignition Current (MICR). Class 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, along with most countries and regions in Europe and around the world, classifies 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).