The explosion-proof three-way junction box is used to connect the electric heating zone with the electric heating zone in the explosion-proof area, to increase the length of the electric heating zone, or to match the electric heating zone and the Trident pipeline with different power on the same pipeline. The explosion-proof sign "eII T4" is suitable for explosive gas mixtures in the first and second zones of the factory after matching with the electric heating belt. Its shell is made of high strength plastic.