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Hazardous areas are locations where flammable gases, vapors, dusts, or fibers may be present, requiring stringent regulations for all electrical installations to prevent explosions or fires. These areas are classified into Zones (in IEC/ATEX systems) or Divisions (in North American systems) based on the likelihood and duration of the presence of the explosive mixture. For piping, this traditionally meant using heavy-duty, explosion-proof metallic conduit. However, specific types of plastic conduit pipe are now permitted in certain classified zones, provided they meet rigorous international and national safety standards. The use of plastic offers benefits like corrosion resistance and non-conductivity, but it requires careful selection to ensure compliance and maintain safety.
The biggest hurdle for using standard plastic conduit pipe in hazardous locations is its potential flammability and its structural integrity under extreme heat. If a fault occurs and a fire starts, standard PVC pipe can contribute to the blaze and release toxic smoke. For this reason, plastic is generally prohibited in the most volatile areas (like Zone 0 or Division 1), where the risk of continuous presence of explosive gas is highest. In these zones, highly durable, explosion-proof metallic conduit is mandatory to contain any internal spark or explosion and prevent it from propagating to the external atmosphere.
The application of plastic conduit pipe is usually restricted to lower-risk areas, such as Zone 2 or Division 2, where flammable substances are only likely to be present under abnormal operating conditions (e.g., during equipment failure). In these zones, certain types of rigid non-metallic conduit (RNC), particularly PVC pipe, can be used if they carry the required safety certifications and are installed in accordance with local fire codes. This is typically done when corrosion resistance is essential, such as in chemical storage facilities where metal would quickly degrade.
Another critical use for plastic conduit pipe in hazardous environments is the protection of intrinsically safe (IS) wiring. IS systems operate with such low power and energy levels that they are incapable of generating a spark hot enough to ignite an explosive atmosphere. When running IS wiring alongside non-IS wiring, the low-energy cables must be segregated. Color-coded (usually light blue) plastic conduit pipe is frequently used for this purpose, acting as a highly visible, non-conductive, and protective barrier to clearly identify and separate the safe circuits from the high-energy circuits, thus preventing cross-contamination of energy.
The final decision on whether a plastic conduit pipe can be used always rests on its official safety certification. Any non-metallic conduit used in a hazardous area must be listed and labeled by recognized testing laboratories (such as UL in North America or adherence to ATEX/IECEx standards internationally). These certifications verify the conduit's fire resistance, resistance to physical damage, and suitability for the specific gases or dusts present in the installation area. Without proper listing for the specific class, division, or zone, plastic PVC pipe conduit cannot be legally or safely installed.
While standard PVC has limitations, specialized non-metallic conduits can be safely deployed in specific hazardous areas, particularly in lower-risk zones or for intrinsically safe wiring segregation, owing to their non-conductive and corrosion-resistant properties. As a leading manufacturer in the plastic conduit pipe market, LESSO has developed extensive expertise over decades to deliver superior protective products for electrical applications. This dedication ensures that LESSO consistently provides certified and high-quality non-metallic conduits suitable for demanding and regulated industrial environments.
