They are designed to contain internal explosions and prevent ignition of surrounding flammable gases or dust. In this article, we will explore three key aspects: certification standards, material selection, and application-specific design considerations. Explosion proof distribution boxes and. ● Plug, socket and built-in explosion-proof component are separately IECEx and ATEX certified. ● Cable wheel can be hand held or moved with a pull or push. Explosive gas mixtures: Class IIA, IIB, and IIC. Casting aluminum alloy shell or welded steel plate molding, with surface painting. The HVA (Harmonic Voltage Analysis) Voltmeter, Ammeter, Miliammeter units are available with a large number of measuring range options, scaled 2 or 5 times.