Figure 5-5. Flat (ground) joints can be used as an escape path to cool the hot gases as they pass through the flat (ground) joint

DOE-HDBK-1092-98

NEC Article 500

Figure 5-5. Flat (ground) joints can be used as an escape path to cool the hot gases as they pass through the

flat (ground) joint.

In addition, door-interlock switches are required to prevent access to the equipment while the circuits

are energized. All of these accessories can add up to a considerable expenditure. For a detailed

description of purging/pressurizing systems see NFPA 496, "Purged and Pressurized Enclosures for

Electrical Equipment in Hazardous Classified Locations."

5.3 HAZARDOUS LOCATIONS

Hazardous areas and locations are classified by group, class, and division. These classifications are

determined by the atmospheric mixtures of various gases, vapors, dust, and other materials present.

The intensity of the explosion that can occur depends on concentrations, temperatures, and many

other factors that are listed in NFPA codes.

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