Explosion proof Distribution Box is a compact, Ex-certified power solution for hazardous environments. Rated 16A at 220V with dual flush sockets, it's built for Zone 1 & Zone 21 operations. During. This series of products have good explosion-proof function, suitable for IIA, IIB, IIC explosive gas environment and various flammable and explosive sites, mainly used in railway, power, metallurgy, petroleum, petrochemical, chemical, iron and steel, aviation, ships and various factory areas. 1.