4/15/2024 0 Comments Nec concrete encased duct bank![]() ![]() ![]() Once all the runs of conduit are in place and properly connected, the crew fills the trench with cement and the ends of the pipe are directed into and terminate in approved electrical devices or boxes. Once more, CANTEX PVC Pipe Solvent Cement needs to be applied with a dauber in between each run.Ĥ. Once again, the entire installation process needs to be repeated for every 10 or 20 feet, depending upon the length of the conduit.ģ. See the CANTEX Full Product Line Catalog for determining the NEC 70 spacer requirements for the necessary trade size of the spacers and the required separation space. The rows of CANTEX PVC Intermediate Spacers are connected for every row of pipe. The amount of spacers coordinates with how many rows of conduit are being installed. Once the trench is completed, CANTEX PVC Base Spacers must be placed in rows in the trench. The process begins with the crew digging the trench.Ģ. Once again, the process for encasing Direct Burial and Encased Burial PVC Utility Duct in cement is basically the same as the cement encasement process for Schedule 40 and 80 PVC Pipe. Once all the runs of PVC DB Conduit are in place and properly connected, the crew fills the trench with dirt.ĭB Direct Burial & EB Encased Burial Cement Installation This process is repeated every 10 to 20 feet, depending upon the length of the conduit.ĥ. The pipe is twisted slightly to secure it. Once the pipe is smooth, the correct type of CANTEX PVC Solvent Cement gets applied to the inside of the belled end and the outside of the spigot or “straight” end of the conduit with a dauber.Ĥ. The encasement is just to prevent a backhoe from damaging the conduits. If the pipe has been cut, a reamer tool must be used to remove burrs or debris before cementing. In between each run of pipe, the belled end of the conduit gets cemented to the straight end. A crew begins by digging a trench for the conduit.Ģ. Consequently, the ends of the DB PVC Conduit runs are directed into and terminate in approved electrical devices or boxes. The 82' depth is likely the maximum frost depth over a hundred year record period. Only frost heave beneath the duct bank will. Soil frost heave above the bottom of the concrete will not affect the ductbank. For example, smoother select fill dirt would be used as back-fill and there are no above-ground applications for Direct Burial PVC Conduit. thanks again, FWIW, in the design of concrete-encased duct banks, it is the depth of the bottom that is of the most concern. 1).DB Direct Burial PVC Utility Duct InstallationĪlthough the direct burial installation for DB PVC Utility Duct is very much the same as it is for Schedule 40 and Schedule 80 PVC Pipe, there are some differences in back-fill requirements and performance capabilities. Editorial correction filed 11-2-83 (Register 83, No. Reference: Section 142.3, Labor Code and Section 18943(c), Health and Safety Code.ġ. NOTE: Authority cited: Section 142.3, Labor Code. Metallic underground ducts shall be suitably protected from corrosion. 2: Where it is impractical to obtain the depth of cover specified, the depth shall be permitted to be reduced, provided that the duct has sufficient strength itself or adequate protection is installed above the duct to prevent damage to the duct system by any surface traffic. 1: Direct buried conduits to contain cables for series street lighting circuits operating at less than 7,500 volts shall be installed at a depth of at least 24 inches below the surface under which they are located.ĮXCEPTION: No. A lesser depth is permitted for ducts containing cables operating at 35,000 volts or less, if the duct is rigid metallic conduit, Schedule 80 PVC conduit, or equivalent, or if the duct has a layer of concrete at least 3 inches thick above the duct.ĮXCEPTION: No. Underground ducts of rigid metallic steel conduit, Schedule 80 PVC conduit, or equivalent, containing cables operating at a potential above 35,000 volts, shall be installed at a depth of at least 36 inches. High-Voltage Electrical Safety OrdersĪrticle 19.
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