Division of explosion-proof electrical equipment's explosion-proof grades is based on the equipment's usage category, the temperature group of explosive gases, and the explosion-proof type of the electrical equipment. Electrical equipment
Flameproof electrical equipment is divided into two categories: Category I for electrical equipment used in underground coal mines; Category II for electrical equipment used in locations other than mines, distinguished by the Minimum Experimental Separation Gap (MESG) or Minimum Ignition Current (MICR). Category II electrical equipment is further subdivided into three classes: IIA, IIB, and IIC.
The above four categories are primarily based on the potential spark quantities that can cause ignition under different working 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. The ignition temperature is denoted as t (°C).