Generally, conduit seals are required within 18 inches of the point of entry to explosion-proof enclosures. This requirement seeks to contain explosions and flames within the enclosure and prevent them from being rapidly transmitted through the conduit systems. (1) Cast or welded enclosures shall be designed to withstand a minimum internal pressure of 150 pounds per square inch (gage). Castings shall be free from blowholes. One prime source of energy is electricity. Equipment such as switches, circuit breakers, motor starters, pushbutton stations, or plugs and. 2. Correctly selected and installed equipment helps prevent ignition of explosive atmospheres while allowing industrial. This section sets forth requirements for electric equipment and wiring in locations which are classified depending on the properties of the flammable vapors, liquids or gases, or combustible dusts or fibers which may be present therein and the likelihood that a flammable or combustible. Explosion-proof plugs and sockets protect people and equipment in hazardous areas. These devices block sparks and heat that could cause explosions.
