SECTION: 33 71 02 UNDERGROUND ELECTRICAL DISTRIBUTION
READ FIRST - All JBLM utility distribution system work must be coordinated through the ESD Utilities Branch upon the start of project scoping.
1. As of 1 July 2019, City Light and Power (CLP) is now responsible for JBLM's Electrical Distribution system and hereby known as the electrical system owners. The system point of demarcations are the primary power lines while the secondary lines will remain with the DPW shops. The primary distribution system includes JBLM-Main, McChord Field, North, and all associated areas. Excluded areas include Yakima Training Center and JBLM areas not geographically located near JBLM-Main.
2. The electrical utility privatization contract, SP0600-18-C-8327, was awarded through the Defense Logistics Agency (DLA) and is being administered by Directorate of Public Works, Engineering Services Division, Utilities Branch. For contract questions, concerns, or interpretations Government points of contact include the Contracting Officer Representative (COR), Mr. Francisco de la Torre 253-967-3750, Franciso.email@example.com and Utilities Branch Chief, Ms. Royanna Solis 253-966-3282, Royanna.firstname.lastname@example.org
3. Per DA Memo dated April 24, 2018, all utility system infrastructure improvements and additions associated with privatized utility systems are to be accomplished through use of the cognizant Utilities Privatization System Owner, unless an exception has been granted.
4. Per the privatization contract, CLP is responsible for design, construction, and connection to the JBLM electrical distribution system. As each project begins, the project manager shall refer to the Service Connection Manual and submit a Service Connection Application to begin the process of coordination. The JBLM Service Connection Manual is provided here along with the Service Connection Application that must be filled out for each project that connects or effects the electrical distribution system.
5. CLP's Construction standards are to be used for all project associated with the privatized utility systems. These standards are provided for information to A-E's and project managers.
The UFGS Section 33 71 02 will not be used for CLP design and construction.
- Quality Assurance: EP415-1-261, Volume 4
- UFGS SECTION 33 71 02 UNDERGROUND ELECTRICAL DISTRIBUTION
- IEEE C2 National Electrical Safety Code
- UFC 3-550-01, Exterior Electrical Power Distribution with Change 1
- Resource Conservation and Recovery Act (RCRA) , Section 6002
- Federal Sustainable Acquisition Items/Requirements
- Executive Order 13834
- DoD Green Procurement Policy (Aug 27 2004)
- DoD Green Procurement Strategy (Nov 2008)
- Army Green Procurement Policy (Nov 22 2006)
- Federal Acquisition Regulation, Part 23
- EPA Final Guidance on Environmentally Preferable Purchasing
- HJB Form 225 (JBLM Sustainable Acquisition Exception Form)
- UFC 1-200-2 (High Performance and Sustainable Buildings Requirements)
- ASA IE&E Sustainable Design and Development Policy (Jan 17 2017)
- 33 71 02 Underground Electrical Distribution
Changes or Criteria Notes to Unified Facilities Guide Specifications (UFGS)
Paragraph # and Title (if any)
Note to Designer
For areas not included in the above electrical utility privatization, the below design requirements still apply.
a. The governing primary code document is UFC 3-550-01; the secondary governing code document is NFPA 70 and IEEE C2.
b. All designs shall be reviewed and approved by the Joint Base Lewis - McChord Department of Public Works. All new construction installation, remodel, and retrofit work requires inspection and acceptance by the Joint Base Lewis - McChord Department of Public Works.
c. General: JBLM Primary power distribution is a 13,800-volt, 3-phase, 3-wire single-point grounded wye system. JBLM has adopted Tacoma Public Utilities (TPU) utility design criteria and construction standards for all power distribution work performed on the Installation. Design and construct in accordance with TPU standards, except for requirements associated with single-point grounding. The "single-point grounding" portion of the JBLM distribution system applies to a single reference point to ground at the substations only. JBLM is, for all intents and purposes, a Delta System, so the neutral conductor shown on the TPU details should be disregarded. Refer to TacomaPower.com for construction details and specifications and to JBLM Exterior Electric Shop at (253)-967-5840 for any questions regarding system requirements. TPU's utility design criteria and construction standards are applicable for all power distribution work that does not conflict with specific JBLM standards. Conflicts shall be clarified with contact to the Exterior Electric Shop. Because the Tacoma Power web site standards are subject to change beyond JBLM's control please verify any discrepancies/omissions with JBLM POCs. Comply with the most current National Electrical Safety Code (NESC ANSI C-2), NFPA 70 and TPU standards for the Work of this Contract.
(1) Design, furnish, and install a 15kV class distribution system that extends from the existing system, provides power for the facilities in this project, and provides expansion capability for future projects. Coordinate the distribution system expansion with the Public Works Electrical System Manager Engineer and the Exterior Electric Shop. Where new risers are to be installed to transition from the existing overhead system to a new underground system, design shall include the replacement of poles that are 20 years old.
(2) Demolition: Turn over any existing distribution equipment required to be removed under this contract to the Public Works Exterior Electric Shop. Coordinate turnover with the Exterior Electric Shop Foreman.
(3) Seismic Bracing: Brace or anchor distribution equipment to resist horizontal forces acting in any direction per the site class and seismic use group as defined in the International Building Code and ASCE 7.
(4) System Coordination Study: Provide a coordination study to demonstrate that the equipment selected and system constructed meets the contract requirements for equipment ratings, coordination, and protection. Perform an arc flash study to determine the required personal protection equipment (PPE). Mark panelboards and other electrical equipment that require work when energized with PPE requirements per NFPA 70E Section 130.3(C). A registered professional engineer with demonstrated experience in power system coordination shall perform the study. Start coordination study at the first device located upstream of the equipment to be installed. Coordinate with JBLM Exterior Electric Shop for upstream device information and for system fault currents. AE shall determine or acquire the system available short circuit current and X/R ratio required for the study by either analysis or by contacting TPU Tacoma for the current substation values and calculating the values for the subject project location. Upon completion of the study, update JBLM's power distribution model to reflect the addition of this project to the distribution system.
d. Primary Duct Banks: Medium-voltage ducts shall be minimum 4-inch Schedule 40 PVC encased in 2,000 psi controlled density fill (CDF) or concrete. Provide Schedule 40 PVC ducts encased in 3,000 psi reinforced concrete in duct banks under roads or paved areas subject to vehicular traffic. Burial depth to the top of the concrete encasement of all primary duct banks shall be 36 inches, minimum. Not less than 3 inches of concrete encasement around the duct shall be provided. Provide a 6-inch wide metallic warning tape above primary duct banks at 12 inches below finished grade. Arrange ducts so that they enter manholes and vaults at the lowest point. Where main, 500kcmil parallel runs of medium voltage primary conductors are to be provided, provide at least two spare ducts. Otherwise, provide at least one spare duct in all medium-voltage duct banks. Provide a pull cord in all spare ducts. For all main feeders, provide one 4 inch duct in the duct bank for the SCADA system. Provide bare copper ground conductor in the duct bank encasement and ground the conductor in all vaults. Minimum size is #2 for lateral feeder, #2/0 for lateral main feeder and #4/0 for main feeder. When locating power and telecom in the same duct bank, maintain a 6 inch separation between the surfaces of each duct. No buildings and structural pads shall be installed on the top of duct banks. All main feeders ducts shall be three 5-inch Schedule 40 PVC and one 4-inch Schedule 40 PVC encased in 2,000 psi controlled density fill (CDF) or concrete. Provide Schedule 40 PVC ducts encased in 3,000 psi reinforced concrete in duct banks under roads or paved areas subject to vehicular traffic.
e. Medium-Voltage Conductors: All medium-voltage conductors shall be installed in primary duct banks and shall be 15kV, EPR, CU, 133 percent insulation, with insulation shielding. Main feeders shall be installed in 5 inch Schedule 40 PVC ducts, shall have 600-ampere terminations, and shall be either 750kcmil or 2 sets of 350kcmil; loop lateral main feeders shall be #4/0 AWG in 4 inch Schedule 40 PVC ducts with 200-ampere terminations; and lateral feeders to transformers shall be #2 AWG in 4 inch Schedule 40 PVC ducts.
(1) Splicing: Where splicing is required, provide 4-way in-vault junction assemblies in an appropriately sized vault, minimum size 7 feet x 7 feet x 6 feet deep, with a double hinged diamond-plate lid. Angle assemblies upward at a 45-degree angle to facilitate above-ground operation. All 200-ampere medium-voltage separable insulated connectors shall be of the load-break type. In-line and T-tap primary splices are not permitted. Provide test points on elbows at junction assemblies, pad-mount transformers and switches.
(2) Fire Taping: Provide fire protective tape on all medium-voltage conductors in manholes and in vaults under transformers, switches, and in-vault junction assemblies.
(3) Labeling: Label all cables by means of fiber, laminated plastic, or nonferrous metal tags indicating the cable type, conductor size, circuit number, circuit voltage, cable destination, and phase identification. Coordinate labeling requirements with PW.
(4) Testing: Provide DC hi-potential testing, shield continuity, and phase rotation testing on all new primary conductors prior to energizing the cables. Testing shall be done by an independent third party testing agency.
f. Manholes and Vaults: Manholes and Vaults shall be a minimum of 810LA (8' W x 10' L x 8' H) for 4-way switches or 812LA (8'-10" W x 12' L x 8' H) for 6-way or greater switches in all new construction and comply with minimum cable bending radius requirements according to the current edition of the National Electrical Safety Code (NESC). Install manholes at street intersections to facilitate street crossings and space them a maximum of 500 linear feet apart or less as required to minimize pulling tension on the conductors. Provide vaults under all transformers and distribution switches with external man access hatch and with the pad-mount serving as a portion of the lid for the vault. Provide a minimum 6-inch diameter knockout at the bottom of the vault for drainage. All Pad-mounted type equipment shall be installed on a vault unless otherwise indicated. All vaults/manholes lid shall be galvanized diamond plate double hinge doors with locking bolts, WSDOT, H-30, or approved equal.
(1) Conductor Installation: Secure conductors to insulators on racks on all four walls of vaults, with secondary conductors mounted at least 8 inches above medium-voltage conductors. All conductors shall be looped and racked a minimum of 360 degrees, and arranged in an approved manner that provides safe and rapid access to personnel during installation and maintenance. Conductors shall enter and exit the vault in such a way as to maintain the same direction of rotation, either clockwise or counterclockwise as appropriate.
(2) Vault Penetrations: Properly seal all vault penetrations with waterproof grout to prevent water and moisture from entering the vault. Ducts shall be installed with the bell end flush with the inside wall surface of the vault.
(3) Conduits: Install conduits with secondary conductors above conduits with medium-voltage conductors.
(4) Vault Grounding: Provide a ground ring around the inside of all vaults and a ground ring around the exterior of all vaults. Provide at least two connections between the Inner ground ring and the Outer ground ring. The outer ground ring shall consist of a #4/0 bare copper conductor and four 3/4-inch x 10-foot long ground rods. The outer ring shall be installed so that between ground rods the conductor is 36 inches deep (catenary shape) and 36 inches away (horizontally) from the vault. Connections to the ground rods shall be 12 inches below grade. Three connections shall be of the exothermic weld type and one connection shall be compression type with/in a test well.
g. Junction Pedestals: Provide junctions above ground or in manholes/vaults. Where four-way junctions are installed in vaults, provide manhole/vault with diamond plate, two-section steel covers and set junctions upwards at a 45-degree angle to allow for hook-stick operation from above the manhole/vault. Include insulated-bushing type parking stands adjacent to each separable load-break elbow to provide for cable isolation. Above-ground junction pedestals are required where the number of junctions exceeds four.
h. Distribution Switches: Primary distribution switches shall be fused, dead-front, bio-preferred liquid-filled, above-ground, oil and vacuum type. All switch taps shall be switchable and 200A taps shall be fused. Install switches above ground on concrete vaults with external man access door and with the switch pad serving as a portion of the lid for the vault. Provide a ground ring around all pad-mounted switches as described in the Vault Grounding paragraph above.
i. Pad-mount Distribution Transformers: Furnish and install liquid-filled, pad-mounted transformers for the facility in the project. Locate transformers to comply with AT/FP requirements. Based on the electrical load of the facility or facilities to be served, determine the KVA capacity and low-voltage rating of the transformer. Install outdoor, medium-voltage transformers on vaults.
(1) Transformer Specifications: Distribution transformers shall be new, loop-feed, with two separate windings per phase and shall be of the less-flammable, liquid-insulated type with bio-based biodegradable dielectric liquid derived from natural esters, complying with IEEE C57.12.00 and IEEE C57.12.21. Transformers shall be dead-front, equipped with oil-immersed bayonet-type overload fuses in series with partial range current-limiting fuses, five primary taps (two-above and two-below nominal), and three two-position load-break switches to permit opening and closing of either side of the loop, and the ability to de-energize the transformer with the loop remaining energized. Permanently attach high-voltage warning signs to each side of the transformer and include transformer KVA rating, secondary voltage and phase information at the front door of the secondary compartment. Provide copper-faced or stainless steel ground connection pads in the high- and low-voltage compartments, a dial-type thermometer, pressure-relief valve, liquid-level gauge, and drain valve. Provide oil sampling tube on transformers 500kVA and above. Provide removable MOV surge arrestors with removable grounds on the unused side of loop transformers, where applicable. Where the transformer is used as a feed-through, provide fault indicators. Provide insulated bushing-type parking stands adjacent to each separable load-break elbow to provide for cable isolation. Provide padlock hasps and locks Coordinate lock style and material with the PW Exterior Electrical Shop. Provide bollards for protection in locations vulnerable to vehicular traffic per TPU standards.
(2) Primary Connections: Primary underground-to-overhead conductor connections shall be Burndy WEJTAP, Tyco AMPACT Wedge, or approved equal. Provide mechanical connectors at arrestor grounds.
(3) Distribution Cutouts: Where the existing overhead primary is tapped for service to a pad-mount transformer, the distribution fused cut-outs shall be of the load-break, silicone type that meets the following criteria: Open outdoor load-break fused cut-out with Type K fuses conforming to NEMA C37.42 with rated amperes to match system requirements. Minimum fuse rating shall be 100 amperes. Install silicone rubber insulators, clamshell terminal connectors, NEMA B bracket, 12 kAIC symmetrical fault-interrupting current rating, with solid cap fuse holder.
(4) Secondary Connections: Secondary conductor connections shall be compression type. Provide antioxidant compound where required by code. No penetrations are allowed through the transformer casing.
(5) Transformer Grounding: Provide a grounding ring (counterpoise) around each transformer that consists of a buried #4/0 bare copper conductor and four 3/4-inch dia. x 10-foot long ground rods. The ground ring shall be placed 36 inches away, horizontally, from the transformer pad and 36 inches deep (catenary shape) between rods. Ground the transformer per NESC for a single-point grounded wye distribution system, with secondary neutral ground isolated from equipment ground and the ground strap removed. Neutral ground shall be 600V insulated copper wire at least 20 feet away from the transformer grounding ring and at least 90 degrees apart from the primary duct bank, with Neutral ground conductor mounted at least 8 inches above the medium voltage ground conductor. The top of all the ground rods shall be installed 12 inches below grade and all ground cables shall be installed 36 -inches below grade. Below-grade three ground connections shall be of the exothermic type and one ground connection shall be of compression type with/in a test well. Refer to JBLM standard details (Division 33 - Utilities, Section 33 71 02 - Underground Electrical Distribution) for grounding.
(6) Transformer Pad: Transformers shall sit on a concrete pad sized to serve as a portion of the lid for the vault below the transformer. Pads for all transformers shall include an external man access into the vault without removing the transformer. Access into the vault shall be through a double-hinged diamond plate lid. Vaults for small transformers serving roadway utility loads, such as street lighting and traffic signals, may be 5 feet x 7 feet x 5 feet with pad-mount that includes external man access. All pads shall extend 6 inches beyond the transformer enclosure.
j. Distribution System Model: Contractor shall update the distribution system model (SCADA, CYME, EasyPower, etc.) after each change (with controls and constraints). Coordinate with Exterior Electric Shop for update.
k. 600-volt Distribution: Provide a 600V underground distribution system from the secondary side of all transformers installed for service to buildings within the scope of this project. Cables shall be copper with 90-degree C insulation and suitable for use in an underground duct system. All secondary duct banks shall be direct-buried Schedule 40 PVC with a minimum of 3 inches of sand above and below ducts, except under roads or paved areas subject to vehicular traffic, and shall contain at least one spare duct. Provide Schedule 40 PVC in duct banks under roads or paved areas subject to vehicular traffic, encased in 3,000 psi reinforced concrete. Minimum burial depth shall be 30 inches below finished grade. Provide a 6 inch metallic warning tape above secondary ducts at 12 inches below finished grade. Determine the secondary conductor size, duct size and quantity based on the transformer rating and building service requirements, adjusted for voltage drop. Secondary conductors shall not be larger than 500kcmil. Provide galvanized rigid steel (GRS) conduit long-radius elbows and transitions from below to above grade and into buildings. Provide PVC coated GRS conduit, wrap elbows or double-layer tape wrap all GRS conduits 12 inches minimum above grade and all conduit below grade to prevent corrosion. Provide compression type-connectors at the transformer secondary and the building service entrance switchboard. All spare conduits shall be installed with pull cord and covered with a metal or rubber cover.
l. Grounding: Soil resistivity at JBLM is extremely high, requiring additional measures to be taken in the grounding system design. Submit design drawings and calculations based on soil resistivity data and include measures such as counterpoise systems, buried plates, chemical grounds, and bentonite backfill to achieve a 25-ohm maximum resistance for the exterior distribution system.
(1) Transformers, Switches, and Manholes. At a minimum, grounding shall consist of a counterpoise/ground ring composed of 3/4-inch x 10-foot minimum copper clad steel ground rods interconnected by a stranded bare #4/0 copper conductor with at least one test well.
(2) Buildings. Grounding and bonding shall comply with Article 250, NFPA 70. To achieve the 10-ohm maximum resistance required by I3A for the earth electrode subsystems at the building, provide a counterpoise grid system composed of 3/4-inch x 10-foot minimum copper clad steel ground rods interconnected by a stranded bare #4/0 copper wire around the perimeter of the building. The counterpoise/ground ring shall be installed 36-inches below grade and 6-feet away from the building footings. Install at least one test well for testing the grounding system. For buildings greater than 200-foot perimeter length, install at least two test wells (diagonal corners). For buildings greater than 400-foot perimeter length, install at least four test wells (all corners). Install the ground rods in 20-foot increments around the perimeter of the building.
(3) Connections: Make connections using exothermic welds below grade for connections to electrical panels, communications system grounds, building steel and static ground points. Exposed ground connections shall be removable pressure type. The connections between the ground ring conductor and the rods shall be made by exothermic weld except at the test well. The connections to the rod at the test well access point shall be removable pressure type.
(4) Test Wells: The test well shall be a 12 inch diameter cylinder and 24 inches deep. Fill test well with fine gravel up to 18 inches below grade. The test well lid shall be metal and shall be installed with a grounding strap between the lid and the ground rod. The ground rod shall be installed 12 inch below grade.
m. Lightning Protection System: If the calculations required by NFPA 780 indicate that a lightning protection system is required for the building, provide a lightning protection air terminal that is 2 -feet tall, minimum. The roof-run conductors shall be bare #1/0 copper conductors. The down conductors shall be bare #2/0 copper conductors and connected to the grounding system (counterpoise/ground ring, ground rods) without touching any building metal. Install the down conductor in 1-inch Schedule 80 PVC, minimum 10 ft above grade.
n. At transition area (from Underground to Above ground or vice versa), install Schedule 40 long radius GRS elbow - wrapping with a corrosion proof tape, 12 inch above grade and 12 inch below grade.
Notes to Designers on Drawing Content
Junction Vault EUG-02_33 71 02
Pull Vault EUG-03_33 71 02
Underground Service EUG-04_33 71 02
Applicable Points of Contact