Attachment No 1 - 26 05 41 - UNDERGROUND ELECTRICAL CONSTRUCTION - Revised 8-1-24.pdf

HAMPTON NATIONAL CEMETERY PROJECT NO. 849-MM22-06

DESIGN THE CONDUIT INSTALLATION FOR NEW COMMUNICATION FEED APRIL 7, 2023

100% DESIGN SUBMISSION

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SECTION 26 05 41

UNDERGROUND ELECTRICAL CONSTRUCTION

PART 1 - GENERAL

1.1 DESCRIPTION

A. This section specifies the furnishing, installation, and connection of underground ducts and raceways, and precast manholes and pullboxes to form a complete underground electrical raceway system.

B. The terms “duct” and “conduit” are used interchangeably in this section.

1.2 QUALITY ASSURANCE

A. Coordinate layout and installation of ducts, manholes, and pullboxes with final arrangement of other utilities, site grading, and surface features.

1.3 SUBMITTALS

A. Submit in accordance with Paragraph, SUBMITTALS in Section 26 05 11, REQUIREMENTS FOR ELECTRICAL INSTALLATIONS, and the following requirements:

1. Shop Drawings:

a. Submit sufficient information to demonstrate compliance with drawings and specifications.

b. Submit information on manholes, pullboxes, ducts, and hardware. Submit manhole plan and elevation drawings, showing openings, pulling irons, cable supports, cover, ladder, sump, and other accessories.

c. Proposed deviations from the drawings shall be clearly marked on the submittals. If it is necessary to locate manholes, pullboxes, or duct banks at locations other than shown on the drawings, show the proposed locations accurately on scaled site drawings, and submit to the COR for approval prior to construction.

2. Certifications: Two weeks prior to the final inspection, submit the following.

a. Certification by the manufacturer that the materials conform to the requirements of the drawings and specifications.

b. Certification by the Contractor that the materials have been properly installed, connected, and tested.

1.4 APPLICABLE PUBLICATIONS

A. Publications listed below (including amendments, addenda, revisions, supplements, and errata) form a part of this specification to the extent referenced. Publications are referenced in the text by designation only. The most recent publication of each referenced standard below shall apply.

B. American Concrete Institute (ACI):

Building Code Requirements for Structural Concrete

318-14/318M Building Code Requirements for Structural

Concrete & Commentary

SP-66 ACI Detailing Manual

C. American National Standards Institute (ANSI):

77 Underground Enclosure Integrity

D. American Society for Testing and Materials (ASTM):

C478 REV A

Standard Specification for Precast Reinforced

Concrete Manhole Sections

C858 Underground Precast Concrete Utility

Structures

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C990

Joints for Concrete Pipe, Manholes and

Precast Box Sections Using Preformed Flexible

Joint Sealants.

E. National Electrical Manufacturers Association (NEMA):

TC 2 Electrical Polyvinyl Chloride (PVC) Conduit

TC 3

Polyvinyl Chloride (PVC) Fittings for Use With

Rigid PVC Conduit And Tubing

TC 6 & 8

Polyvinyl Chloride (PVC) Plastic Utilities Duct

For Underground Installations

TC 9

Fittings For Polyvinyl Chloride (PVC) Plastic

Utilities Duct For Underground Installation

F. National Fire Protection Association (NFPA):

70 National Electrical Code (NEC)

70E National Electrical Safety Code

G. Underwriters Laboratories, Inc. (UL):

6 Electrical Rigid Metal Conduit-Steel

467 Grounding and Bonding Equipment

Schedule 40, 80, Type EB and A Rigid PVC

Conduit and Fittings

651A Schedule 40 and 80 High Density Polyethylene

(HDPE) Conduit

PART 2 - PRODUCTS

2.1 PULLBOXES

A. General: Size as indicated on the drawings. Provide pullboxes with weatherproof, non-skid covers with recessed hook eyes, secured with corrosion- and tamper-resistant hardware. Cover material shall be identical to pullbox material. Covers shall have molded lettering, ELECTRIC or SIGNAL as applicable. Pullboxes shall comply with the requirements of ANSI 77 Tier 22 loading. Provide pulling irons, 22 mm (0.875 inch) diameter galvanized steel bar with exposed triangular-shaped opening.

B. Concrete Pullboxes: Shall be monolithically-poured reinforced concrete.

2.2 DUCTS

A. Number and sizes shall be as shown on the drawings.

B. Ducts (direct-burial):

1. Rigid metal conduit: UL 6 and NEMA RN1 galvanized rigid metal, half-lap wrapped with 10 mil PVC tape.

2. Direct burial plastic Conduit UL 651 and UL 651A, heavy wall PVC or high-density polyethylene (HDPE)

2.3 WARNING TAPE

A. 4-mil polyethylene 75 mm (3 inches) wide detectable tape, red with black letters, imprinted with “CAUTION - BURIED ELECTRIC CABLE BELOW” or similar.

2.4 PULL ROPE

A. Plastic with 890 N (200 lb) minimum tensile strength.

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PART 3 - EXECUTION

3.1 PULLBOX INSTALLATION

A. Assembly and installation shall be per the requirements of the manufacturer.

1. Install pullboxes level and plumb.

2. Units shall be installed on a 300 mm (12 inches) thick level bed of 90% compacted granular fill, well-graded from the 25 mm (1 inch) sieve to the No. 4 sieve. Granular fill shall be compacted with a minimum of four passes with a plate compactor.

B. Access: Ensure the top of frames and covers are flush with finished grade.

3.2 TRENCHING

A. Before performing trenching work at existing facilities, a Ground Penetrating Radar Survey shall be carefully performed by a certified technician to reveal all existing underground ducts, conduits, cables, and other utility systems.

B. Work with extreme care near existing walls, ducts, conduits, and other utilities to avoid damaging them.

C. Cut the trenches neatly and uniformly.

D. Individual conduits to be installed under existing paved areas and roads that cannot be disturbed shall be jacked into place using rigid metal conduit, as approved by the COR.

3.3 DUCT INSTALLATION

A. General Requirements:

1. Ducts shall be in accordance with the NEC, as shown on the drawings, and as specified.

2. Join and terminate ducts with fittings recommended by the manufacturer.

3. Slope ducts to drain towards manholes and pullboxes, and away from building and equipment entrances. Pitch not less than 100 mm (4 inches) in 30 M (100 feet).

4. Install insulated grounding bushings on the conduit terminations.

5. Radius for sweeps shall be sufficient to accomplish pulls without damage. Minimum radius shall be six times conduit diameter.

6. Duct lines shall be installed no less than 300 mm (12 inches) from other utility systems, such as water, sewer, chilled water.

7. Duct lines shall terminate at window openings in manhole walls as shown on the drawings. All ducts shall be fitted with end bells.

8. Couple the ducts with proper couplings. Stagger couplings in rows and layers to ensure maximum strength and rigidity of the duct bank.

9. Keep ducts clean of earth, sand, or gravel, and seal with tapered plugs upon completion of each portion of the work.

10. Duct Identification: Place continuous strip of warning tape approximately 300 mm (12 inches) above ducts before backfilling trenches. Warning tape shall be preprinted with proper identification.

11. Duct Sealing: Seal ducts, including spare ducts, at building entrances and at outdoor terminations for equipment, with a suitable non-hardening compound to prevent the entrance of foreign objects and material, moisture, and gases.

12. Use plastic ties to secure cables to insulators on cable arms. Use minimum two ties per cable per insulator.

B. Direct-Burial Ducts:

1. Install direct-burial ducts only where shown on the drawings.

2. Tops of ducts shall be:

a. Not less than 600 mm (24 inches) and not less than shown on the drawings, below finished grade.

b. Not less than 750 mm (30 inches) and not less than shown on the drawings, below roads and other paved surfaces.

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c. Additional burial depth shall be required in order to accomplish NEC-required minimum bend radius of ducts.

3. Do not kink the ducts. Compaction shall not deform the ducts.

C. Connections to Existing Manholes: For duct connections to existing manholes, break the structure wall out to the dimensions required and preserve the steel in the structure wall. Cut steel and extend into the duct bank envelope. Chip the perimeter surface of the duct bank opening to form a key or flared surface, providing a positive connection with the duct bank envelope.

3.4 ACCEPTANCE CHECKS AND TESTS

A. Duct Testing and Cleaning:

1. Upon completion of the duct installation, a standard flexible mandrel shall be pulled through each duct to loosen particles of earth, sand, or foreign material left in the duct, and to test for out-of-round conditions.

2. The mandrel shall be not less than 300 mm (12 inches) long, and shall have a diameter not less than 13 mm (0.5 inch) less than the inside diameter of the duct. A brush with stiff bristles shall then be pulled through each duct to remove the loosened particles. The diameter of the brush shall be the same as, or slightly larger than, the diameter of the duct.

3. If testing reveals obstructions or out-of-round conditions, the Contractor shall replace affected section(s) of duct and retest to the satisfaction of the COR.

4. Mandrel pulls shall be witnessed by the COR.

END OF SECTION