Concrete Encased Duct Bank Design

Boxes and not concrete manholes.

Concrete encased duct bank design.

554 2 ft 3 20 5 yd 3. Minimum concrete coverage on left. Duct bank width. Do not use concrete blocks or other means to support and space conduits that are to receive concrete encasement.

Concentration of circuits via the same route are planned or expected. From gradeto the top of duct bank shall be a minimum of 610 mm 24 inches. Use walls of trench to form side walls of duct bank where soil is self supporting and concrete. Minimum concrete coverage on right.

Load density is significant. The top layer of concrete on the duct bank shall be red concrete. A metallic backed marking tape shall be installed 12 above all underground conduits and duct banks. Concrete encasement shall extend a minimum of 76mm 3 inches from any conduit in the bank to the outside surface.

For concrete encased conduits use manufactured pvc spacers and mounts for support and spacing of the conduits. Conduit stub ups shall be rigid steel. Volume of duct bank. Reinforce concreteencased duct banks where they cross disturbed earth and where indicated.

Minimum concrete coverage on bottom. Underground concrete encased electric conduit duct banks shall consist of type db 60 polyvinyl chloride pvc conduit rated for 90 c cable and meeting nema standard tc 6 and astm f 512 for underground applications. Additional circuits will be added routinely.