From a technical point of view, it is feasible to drill holes in the explosion-proof box. GR Type Conduit Outlet Box, Explosion-Proof, Dust-Ignitionproof, Malleable Iron, Unilet, GRT Hub Type. Includes: Internal Ground Screw and O-Ring, Internally Threaded Surface Cover with 3. Category:. GUE and GUB junction boxes are used in threaded rigid conduit systems in hazardous areas: • 15To function as a splice box, pull box or equipment and device enclosure • To house wiring • 3Indoors and outdoors Features: • Threaded construction throughout permits use in hazardous areas • Bodies have. ·Flameproof enclosure (Ex db), which can be used as feed distribution equipment in control and distribution system (such as distribution box, switch box of main circuit, control box, terminal box or motor starting box etc. ) Enclosure: 304 stainless steel, 316L stainless steel and Q235. ·Equipped. Custom Drilling and tapping in Nema 7/9 explosion proof enclosures is not a task that should be left up to just any machine shop or done in the field with hand tools. Always check to see if the shop has a hazardous location UL NNY certificate and is familiar with the specific UL code for drilling. The main function of the explosion-proof distribution box is to ensure the normal operation of electrical equipment in flammable and explosive environments and to prevent explosion accidents caused by electrical sparks. The Electronic Code of Federal Regulations (eCFR) is a.