DESIGN A/E NOTE - GUIDE SPECIFICATION CONVENTIONS
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Rev 19JUN09 j:\Projects\Active\com-deca_design_criteria_revisions-04071\Guide Specifications\TJG Innformation
SECTION 16375
UNDERGROUND ELECTRICAL DISTRIBUTION
PART 1 - GENERAL
1.1 RELATED DOCUMENTS
Verify that Section titles referenced in this Section are correct for this Project's Specifications; Section titles may have changed.
1.1.1. Drawings and general provisions of the Contract, including General and Supplementary Conditions and Division1 Specification Sections, apply to this Section.
1.1.2. Medium voltage cables are covered in Section 16124; 600 V cables are covered in Section 16120.
1.1.3. Grounding and Bonding are covered in Section 16060.
1.2 SUMMARY
Edit as required for any additional requirements, such as switchgear.
1.2.1. This section includes underground duct and manhole systems for electrical distribution and communications distribution.
1.3 SUBMITTALS
1.3.1. Submit manufacturer’s cut sheets on each item in this Article according to Division 1 Specification Sections.
1.3.2. Cut Sheet Submittals required for:
1.3.2.1. Electrical and Communication duct components.
1.3.2.2. Manhole components (covers and rings, duct end bells, cable racks and insulators, pulling irons, steps, sump grates, grounding rods, exothermic brazing materials).
1.3.3. Shop Drawings: If manholes are not detailed on the Drawings, provide Shop Drawings showing plan and section views of the manholes to scale, detailing wall thicknesses, reinforcement, and layout of ducts, appurtenances and accessories.
1.4 QUALITY ASSURANCE
1.4.1. Codes and Standards:
1.4.1.1. UL Listed components
1.4.1.2. NFPA-70 National Electrical Code (Latest adopted edition)
1.4.1.3. IEEE C2 (2002) National Electrical Safety Code (NESC)
1.4.1.4. NEMA TC2-1990 Incl. Rev. 1 thru 4 – Electrical Plastic Tubing (EPT) and Conduit (EPC40 and EPC80)
1.4.1.5. UL 651 – Schedule 40 and 80 Rigid PVC Conduit (May 8,m 1981, 4th Ed.)
PART 2 - PRODUCTS É
2.1 ACCEPTABLE MANUFACTURERS
2.1.1. Carlon
2.2 UNDERGROUND DUCT SYSTEM DESCRIPTION
2.2.1. Concrete encased schedule 40 PVC ducts, minimum concrete cover 3 inches. Steel reinforced where passing under pavements or building foundations, and for 3 feet either side.
2.2.2. Concrete for duct encasement shall be not less than 2500 psi. Comply with Section 03300, Cast-in-Place Concrete.
2.2.3. Minimum depth of horizontal runs:
2.2.3.1. Medium voltage electrical lines – 36 inches
2.2.3.2. Low voltage electrical lines (600V or less) – 24 inches
2.2.3.3. Communication lines (Voice or Data) – 24 inches
2.2.4. Use long sweep bends for changes in direction of 10 degrees or more either vertical or horizontal. Ells (90 degree; use only at risers) shall be of galvanized rigid steel conduit.
2.2.5. Use end bells on all conduits terminating in manholes.
2.2.6. Provide traceable marking tape over all underground duct lines, 18 inches below the surface grade. Marking tape is covered in section 16075, Electrical Identification.
2.3 CONDUITS
2.3.1. PVC, schedule 40, Type EB, sizes as indicated on the Drawings.
2.3.2. Fittings shall be designed for the specific conduit used and shall provide a waterproof joint. Fitting material shall exactly match the conduit material.
2.4 GROUNDING
2.4.1. Grounding shall be provided in every manhole. Grounding materials, equipment, methods and testing are covered in Section 16060, Grounding and Bonding.
2.5 MANHOLES
2.5.1. Unless otherwise shown on the drawings, manholes shall be 8 feet x 8 feet square x 6.5 feet high, minimum internal dimensions, designed for traffic loading. Each manhole shall be of concrete, equipped with a 36” D. cast iron traffic rated cover with the appropriate utility designation “ELECTRIC” or “TELEPHONE” cast in the top surface; a bottom sump, not less than 12 inches square or round, with removable cast iron grate directly below the top opening; pulling irons directly across from, and below the elevation of, each duct bank entrance or space for future duct bank entrance; at least 2 brackets for cable rack arms on each wall. Boxed breakout sections shall be provided at each logical future duct entrance location. Precast manholes are acceptable, provided all features specified herein are provided.
2.5.2. Hardware shall be hot-dip-galvanized steel, or cast iron.
2.5.3. Concrete for manholes shall be not less than 4000 psi. Comply with Section 03300, Cast-in-Place Concrete.
2.5.4. Manholes shall be of sufficient mass to prevent floating.
PART 3 - EXECUTION
3.1 UNDERGROUND DUCTS
3.1.1. Ducts shall be stored in a manner to prevent warping or deterioration. Lay ducts on a flat surface protected from direct rays of the sun. Keep ends plugged.
3.1.2. Conduits shall be thoroughly cleaned for laying.
3.1.3. Ducts shall be laid to a minimum grade of 4 inches per 100 LF. Slope may be from a riser to a manhole, from one manhole to the next, or both ways from a high point between manholes.
3.1.4. Conduit joints may be placed side by side horizontally but shall be staggered at least 6 inches vertically in duct banks.
3.1.5. Solvent weld all joints to provide a watertight duct.
3.1.6. During and after construction, all open duct ends shall be plugged to prevent mud or water entry into the conduits. Particular care must be taken to keep conduits clean of concrete and dirt during the course of construction.
3.1.7. Concrete encased duct lines shall be doweled into the manhole wall with reinforcing bars. The earth below the duct bank shall be well compacted to mitigate settlement.
3.1.8. After the duct line is complete, and before any cables are pulled in, a standard flexible mandrel not less than 12 inches long, having a diameter approximately 1/4 inch less than the conduit internal diameter, shall be pulled through each conduit, after which a brush with stiff bristles followed by a rag shall be pulled through each conduit to make certain that no particles of earth, sand, concrete or gravel have been left in the duct. Repeat the process until the cleaning assembly produces minimal additional foreign matter from the duct line.
3.1.9. Install 1/2 inch minimum diameter nylon pull rope in each new duct not used for cables on this project.
3.2 MANHOLES
3.2.1. Manholes shall be constructed approximately where shown. The exact location of each manhole shall be determined after careful consideration has been given to the location of other utilities, grading, and paving. The location of each manhole shall be approved by the Contracting Officer before construction of the manhole is started.
3.2.2. Install manholes plumb and level; oriented so that ducts enter the manhole perpendicularly to the wall surface without excessive changes of duct direction; at an elevation allowing ducts to enter within the center 1/3 of the manhole wall height (considering all necessary duct line slopes).
3.2.3. Build up the manhole cover ring so as to set manhole covers flush with finished pavement; or, in unpaved areas, set manhole covers 1/2” above finished grade.
3.2.4. Provide cable rack brackets on each wall, sufficient to carry cables through the manhole without excessive sagging, but not less than two on each wall. Provide cable rack arms and insulators sufficient for cables installed on this project, plus an equal number of spares, all installed on the brackets.
3.2.5. Clean all dirt and construction debris from each manhole when all work is completed.
END OF SECTION 16375
<insert project name and location>
June 2010
UNDERGROUND ELECTRICAL DISTRIBUTION
16375-5