8._Underground_Electrical_Transmission_and_Distribution.pdf

QUUG 11-1016 SOW

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SECTION 33 71 02

UNDERGROUND ELECTRICAL TRANSMISSION AND DISTRIBUTION

PART 1 GENERAL

1.1 DESIGN REFERENCES: Provide the design and installation in accordance with the following references. This list is not inclusive and shall be used as a guide that shall be further developed by the Prime Contractor’s A-E hired firm. The publications are referred to in the text by the basic designation only.

AMERICAN NATIONAL STANDARDS INSTITUTE (ANSI)

ANSI C80.1 (2005), American National Standard for Electrical Rigid Steel

Conduit (ERSC).

NATIONAL FIRE PROTECTION ASSOCIATION (NFPA)

NFPA 70 (2011) National Electrical Code

MINISTERIO DE INDUSTRIA, TURISMO Y COMERCIO

R.D. 842/2002 Reglamento Electrotécnico para Baja Tensión, texto refundido con las modificaciones realizadas por el R.D.

560/2010.

ASOCIACIÓN ESPAÑOLA DE NORMALIZACIÓN Y CERTIFICACIÓN. (AENOR)

UNE-EN 124 (1995), “Dispositivos de cubrimiento y de cierre para zonas de circulación utilizadas por peatones y vehículos. Principios de construcción, ensayos de tipo, marcado, control de calidad”.

UNE 21123-4 (2010) Cables eléctricos de utilización industrial de tensión asignada 0,6/1 kV. Parte 4: Cables con aislamiento de polietileno reticulado y cubierta de poliolefina.

UNE-EN 50086-1 (2001) Sistemas de tubos para la conducción de cables. Parte

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1: Requisitos generales.

UNE EN 50086-2-4-A1 (2001) Sistemas de tubos para la conducción de cables. Parte 2-

4: Requisitos particulares para sistemas de tubos enterrados

UNE EN 60332-1 (2005). Métodos eléctricos y cables de fibra óptica sometidos a condiciones de fuego. Parte 1: Ensayo de la resistencia a la propagación vertical de la llama para un conductor individual aislado o cable.

UNE EN 50267 (1999), Métodos de ensayo comunes para cables sometidos al fuego.

DEUTSCHES INSTITUT FÜR NORMUNG (DIN)

DIN 2440 Tubos de acero para instalaciones eléctricas.

INTERNATIONAL ELECTROTECHNICAL COMMISSION (IEC)

IEC-60502-2 (2005), Cables de energía con aislamiento extruído y sus accesorios para tensiones nominales desde 1 kV.

1.2 RELATED REQUIREMENTS: Section 26 00 00.00 20, "Basic Electrical Materials and Methods" applies to this section with additions and modifications specified herein.

1.3 DEFINITIONS:

a. In the text of this section, the words conduit and duct are used interchangeably and have the same meaning.

1.4 MINIMUM CONSTRUCTION SUBMITTALS: As determined during the design phase by the Designer of Record (DOR), additional submittals may be added to this outline list.

1.4.1 Product data and manufacturer's catalog data:

a. Conduits and Fittings

b. Underground Medium and Low Voltage Cables

c. Buried Warning and Identification Tape

d. Ground wires

e. Pre-cast manholes and handholes

f. Manhole/handhole covers

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g. Ground rods

h. Exothermic welding

i. Pre-manufactured medium- and low-voltage splices and terminations.

j. Warning signs.

k. Repair mortar.

l. Manhole identification labels.

1.4.2 Test Reports:

a. Field acceptance checks and tests: Identify each cable for medium voltage cable qualification and production tests. When testing grounding electrodes and systems, identify each electrode and system for each test, as well as the resistance and soil conditions at the time the measurement were made.

1.4.3 Drawings:

a. Record Drawings must indicate the location of ground rods, mats, grids, building ground bus, supplementary grounding electrodes, steel building columns, and other metal structures connected to the grounding system. Identify the location of each ground rod and ground-rod assembly and other grounding electrodes by letter in alphabetical order and keyed to the record of ground-resistance tests.

1.4.4 Certificates:

a. Contractor’s or sub-contractor’s certification for installation of high voltage lines up to 30 kV, LAT1 in accordance with ITC-LAT 03 from R.D. 223/2008.

b. Contractor/sub-contractor individual’s personal license for installation of high voltage lines up to 30 kV, LAT1 in accordance with ITC-LAT 03 from R.D.

223/2008.

c. Handhole covers.

1.4.5 Manufacturer’s Instructions:

a. Medium-voltage cable termination installation.

b. Medium- and Low-voltage cable splices installation.

PART 2 PRODUCTS

2.1 MATERIALS AND EQUIPMENT:

2.1.1 Conduits and Fittings:

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2.1.1.1 Plastic Duct for Concrete Encasement and Fittings: UNE-EN 50086-2- 4/A1 or approved equivalent. Polyvynil chloride (PVC) material. To be used underground only.

2.1.1.2 Galvanized Rigid Steel Conduit: DIN 2440 or ANSI C 80.1. To be used underground and aboveground.

2.1.1.3 Fittings: Use fittings suitable for each type of conduit.

2.1.2 Wires and Cables: Cable (conductor) sizes are designated in square millimeters.

Conductor and conduit sizes indicated are for copper conductors unless otherwise noted.

Insulated conductors shall have the date of manufacture and other identification imprinted on the outer surface of each cable at regular intervals throughout cable length. Wires and cables manufactured more than 24 months prior to date of delivery to the site shall not be accepted.

Provide single conductor type cables unless otherwise indicated. Cable characteristics shall be as follows:

2.1.2.1 High Voltage Cable RHZ1 OL 12/20 kV: Free of halogens in compliance with standard (IEC-60502.2) and UNE-EN 50267. The constituting elements of the cable shall be:

- Conductor: Annealed copper class 2.

- Internal semiconductor: composed of extruded semiconductor.

- Insulation: reticulated polyethylene (XLPE).

- Exterior semiconductor: composed of extruded semiconductor.

- Shield, (Screen): copper wire, longitudinal obturation

- (Cover): polyolefin (Z1)

2.1.2.2 Low Voltage Wiring : Connecting conductors shall be flexible class 5 copper and shall be rated 1000 volts nominal capacity with cross-linked polyethylene (XLPE) insulation in accordance with UNE 21123-4. Insulation shall be moisture and heat resistant and be suitable for maximum operating temperature rise of 90ºC. Technical designation RZ1-K, flame retardant (AS), in accordance with UNE-=EN 60332, halogen-free with thermoplastic polyolefin (Z1) jacket.

2.1.3 Buried Warning and Identification Tape: Provide detectable plastic tape (aluminum foil, embedded copper wire, etc.), manufactured specifically for warning and identification of buried cable and conduit. Tape shall be detectable by an electronic detection instrument. Provide tape in rolls, 150 mm minimum width, color coded for the utility involved (yellow for electrical), with warning and identification imprinted in bold black letters continuously and repeatedly over entire tape length. Warning and identification shall be “CAUTION BURIED ELECTRIC

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CABLE BELOW” or similar. Use permanent code and letter coloring unaffected by moisture and other substances contained in trench backfill material.

2.1.4 Pull Rope: Shall be plastic having a minimum tensile strength of 890 N. Leave a minimum of 1 m of slack at each end of the pull wires.

2.1.5 Grounding system: Provide bare copper wire and copper-clad steel ground rods in accordance with UL 467 or UNE-EN 62305, 19x3000mm minimum dimensions. Provide a complete system to provide a resistance to solid ground not to exceed 5Ω.

2.1.5.1 Ground Wires: Ground and bond wires for substations, main panels and distribution points, and ground rod connections must be annealed bare copper, stranded, with 98 percent conductivity. All underground connections shall only be performed by means of exhotermic welding.

2.1.5.2 Ground Rods: Provide ground rods made of copper-clad steel that are not less than 19 mm in diameter and 3.000 mm in length unless otherwise indicated.

2.1.6 Insulators and hardware: Cable rack arms shall be steel or glass reinforced nylon and shall be of the removable type. Slots for mounting cable rack arms shall be spaced at 200 mm intervals. Insulators shall be suitable for the application intended and calculations shall demonstrate proper creepage distance for line voltage.

2.1.7 Manhole covers: Cast-iron (EN-1563) with epoxy-polyester coating (100 µm), articulated cover with safety blocking device to prevent accidental closing of the cover in the open position, hinges integrated in frame, to be opened with special tool. EN124 compliant, class D, E or F as determined during the design. Covers shall be personalized with engraved letters as per base standard “ELECTRICAL” for electric system manholes, and “AIRFIELD LIGHTING” for visual navigation aids system manholes.. Covers for octagonal-shape manholes shall be galvanized steel sheet with sizes and finishes as required to fit in existing manholes.

2.1.8 Transformers: Transformer to be installed in manholes/vaults shall be submergible/vault type, suitable for the voltage and frequencies required and will be provided with proper protective equipment (MOV surge arresters, etc.). Transformer ratings shall be determined during the design phase to feed all existing loads required to continue operating, with additional capacity for future prospective uses.

2.1.9 Exothermic Welding: Joints between structural elements, metal structures and grounding system shall be accomplished by means of exothermic welding using an adequate mold for each situation. Molds not previously approved shall not be used. Underground bare conductors shall only be bonded with exothermic welding, including wire/ground rod bonding.

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2.1.10 T Branch: Use preformed retractable cold branch for RHZ1 OL 12/20 kV cable type QS-2000 for dry insulation cables. Use the manufacturer recommended adaptors of the set for the section of cable to be spliced. The set shall be installed using the manufacturer’s instructions and executed by qualified personnel certified by the manufacturer of the branch kit.

2.1.11 Exterior Medium Voltage Terminal: Use terminals for dry insulation cables type RHZ1 OL 12/20 kV cold retractable QT II J6SE. The set shall be installed using the manufacturer’s instructions and executed by qualified personnel certified by the manufacturer of the terminal.

2.1.12 Low Voltage Cold Shrink Rubber Splice: Provide a cold-shrink rubber splice which consists of EPDM rubber tube which has been factory stretched onto a spiraled core which is removed during splice installation. The installation shall not require heat or flame, or any additional materials such as covering or adhesive. It shall be designed for use with inline compression type connectors, or indoor, outdoor, direct-burial or submerged locations.

2.1.13 Warning Signs: Each manhole shall be provided with a galvanized steel or UV-resistant plastic material electrical warning sign.

2.1.14 Conduit Sealing Compound: Compounds for sealing ducts and conduits in handholes knockouts and conduit risers aboveground shall have a putty-like consistency workable with the hands at temperatures as low as 2 degrees C 35 degrees F, shall neither slump at a temperature of 150 degrees C 300 degrees F, nor harden materially when exposed to the air.

Compounds shall adhere to clean surfaces of fiber or plastic ducts; metallic conduits or conduit coatings; concrete, masonry, or lead; any cable sheaths, jackets, covers, or insulation materials;

and the common metals. Compounds shall form a seal without dissolving, noticeably changing characteristics, or removing any of the ingredients. Compounds shall have no injurious effect upon the hands of workmen or upon materials.

2.1.15 Repair Mortar: Suitable for thicknesses required in project. Sika Mono Top 618 or similar approved.

2.1.16 Cast-in-place Concrete: Provide concrete in accordance with Section 03 30 00 Cast-In-Place Concrete. In addition, provide concrete for encasement of underground ducts with 20MPa minimum 28-day compressive strength.

2.1.17 Manhole Identification Labels: Each manhole cover, existing or new, shall be labeled with an identification plate composed of vinyl film stuck on a composite aluminum panel for sign-plates. Manhole identification numbers shall be of the format ‘x-yyy’, where ‘x’ stands for the feeder number, and ‘yyy’ stands for the manhole number in feeder ‘x’. Font type and size will be Arial, 150 point size, bold, black color with ribbon as shown in project drawings. Vinyl

33 71 02-7 shall be suitable for outdoors applications and UV resistant to prevent fading. Colors shall be as follows (numbers in parenthesis correspond to color coding in the CMYK color model as follows, C/M/Y/K):

- Feeder #1: Black (0/0/0/100) letters on yellow (0/0/100/0) background.

- Feeder #2: Black (0/0/0/100) letters on green (100/0/100/0) background.

- Feeder #3: Black (0/0/0/100) letters on red (0/100/100/0) background.

- Feeder #4: Black (0/0/0/100) letters on light blue (100/0/0/0) background.

2.1.17.1 Composite Aluminum Panel: Panel for sign-plates, composed of two sheets of white-laquered aluminum with composite placed between them, 3mm thick.

2.1.17.2 Vinyl Film: High performance grade polymeric calendered PVC self-adhesive vinyl for printers. 70 micron thickness, tensile strength 47N/25mm2 machine direction. 140 gms minimum release liner minimum weight, white gloss finish.

2.1.17.3 Adhesive for Plates: Install manhole identification plates in manhole covers by means of single or two-component chemical adhesive suitable for outdoors application, weather- and UV-resistant.

PART 3 EXECUTION

3.1 INSTALLATION:

3.1.1 Contractor Damage: The Contractor shall promptly repair any indicated utility lines or systems damaged by Contractor operations. Damage to lines or systems not indicated, which are caused by Contractor operations, shall be treated as "Changes" under the terms of the General Provisions of the contract. If the Contractor is advised in writing of the location of a non-indicated line or system, such notice shall provide that portion of the line or system with "indicated" status in determining liability for damages. In any event, the Contractor shall immediately notify the Contracting Officer of any such damage.

3.1.2 Underground duct with concrete encasement: Construct underground duct lines of individual conduits encased in concrete. Do not mix different kinds of conduit in one duct bank.

Ducts shall have minimum diameter as indicated in drawings. Concrete encasement surrounding the bank shall be rectangular in cross section and shall provide at least 75 mm of concrete cover for ducts. Provide warning tape as specified in paragraph "Buried warning and identification tape".

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3.1.2.1 Slope of Encasement: Duct banks shall have a continuous slope downward toward underground structures and away from buildings with a minimum pitch of 75 mm in 30 meters (0.25%). Excavate trenches along straight lines from structure to structure before ducts are laid so the elevation can be adjusted, if necessary, to avoid unseen obstructions.

3.1.2.2 Test Mandrel: As each section of a duct line is completed, draw a flexible testing mandrel approximately 300 mm long with a diameter less than the diameter of the conduit through each conduit. After which, draw a stiff bristle brush through, until conduit is clear of particles of earth, sand and gravel. Then immediately install end plugs.

3.1.2.3 Conduit Plugs and Pull Rope: New conduit indicated as being unused or spare shall be provided with plugs or conduit sealing compound on each end. Plugs shall contain a hole or screen to allow water drainage. Provide a plastic pull rope having 1 meter of slack at each end of unused empty conduits.

3.1.3 Buried Warning and Identification Tape: Bury tape with the printed side up at the depths shown in drawing details below the top surface of earth or the top surface of the subgrade under pavements.

3.1.4 Cable Pulling: Pull cables down grade with the feed-in point at the highest elevation.

Use flexible cable feeds to convey cables into duct runs. Do not exceed the specified cable bending radii when installing cable under any conditions, including turnups into switches, transformers, switchgear, switchboards, and other enclosures. If basket-grip type cable-pulling devices are used to pull cable in place, cut off the section of cable under the grip before splicing and terminating.

3.1.4.1 Cable Lubricants: Use lubricants that are specifically recommended by the cable manufacturer for assisting in pulling jacketed cables. Lubricant shall not be deleterious to the cable sheath, jacket, or outer coverings.

3.1.4.2 Cable Pulling Tensions: Tensions shall not exceed the maximum pulling tension recommended by the cable manufacturer.

3.1.5 Grounding Systems: Noncurrent-carrying metallic parts associated with electrical equipment shall have a maximum resistance to solid earth ground not exceeding 5 ohms.

3.1.5.1 Grounding Electrodes: Provide cone pointed driven ground rods driven full depth plus 150mm, installed to provide an earth ground of the appropriate value for the particular equipment being grounded. If the specified ground resistance is not met, an additional ground rod shall be provided in accordance with the requirements of NFPA 70 placed not less than 6 feet from the first rod.

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3.1.5.2 Grounding Conductors: Grounding conductors shall be stranded-bare, unless otherwise noted. Perform grounding and bonding in accordance with NFPA 70. Ground exposed, non-current-carrying metallic parts of electrical equipment, including panelboard doors, metallic raceway systems, etc. All splices shall be performed with exothermic welds, including wire/rod, wire/wire and re-bar/wire splices.

3.1.5.3 Manhole Grounding: Loop a 95 mm2 grounding conductor around the interior perimeter, approximately 305 mm above finished floor. Secure the conductor to the manhole walls at intervals not exceeding 914 mm. Connect the conductor to the manhole grounding electrode with 95 mm2 conductor. Connect all incoming 95 mm2 grounding conductors to the ground loop adjacent to the point of entry into the manhole. Bond the ground loop to all cable shields, metal cable racks, and other metal equipment with a minimum 16 mm2 conductor.

3.1.5.4 Fence Grounding: Fences shall be grounded as indicated. Drive ground rods until the top is 305 mm below grade. Attach a 25 mm2 copper conductor, by exothermic weld to the ground rods and extend underground to the immediate vicinity of fence post. Lace the conductor vertically into 305 mm of fence mesh and fasten by two approved compression fittings, one to bond wire to post and the other to bond wire to fence.

3.1.6 Excavating, Backfilling and Compacting: Provide in accordance with Section 31 23

00.00 20 Excavation and Fill.

3.1.7 Reconditioning of Surfaces

3.1.7.1 Unpaved Surfaces: Restore to their original elevation and condition unpaved surfaces disturbed during installation of duct. Preserve sod and topsoil removed during excavation and reinstall after backfilling is completed. Replace sod that is damaged by sod of quality equal to that removed. When the surface is disturbed in a seeded area, re-seed the restored surface with the same quantity and formula of seed as that used in the original seeding.

3.1.7.2 Paving Repairs: Where trenches, pits, or other excavations are made in existing roadways and other areas of pavement where surface treatment of any kind exists, restore such surface treatment or pavement the same thickness and in the same kind as previously existed, except as otherwise specified, and to match and tie into the adjacent and surrounding existing surfaces.

3.1.8 Medium Voltage Cable Terminations: Make terminations in accordance with the written instruction of the termination kit manufacturer.

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3.1.9 Medium Voltage Cable Joints: Provide power cable joints (splices) suitable for continuous immersion in water. Make joints only in accessible locations in manholes by using materials and methods in accordance with the written instructions of the joint kit manufacturer.

3.1.10 MANHOLE IDENTIFICATION PLATES MOUNTING: Stick all manhole new identification plates in each of the manhole covers with number according to the new numbering system that shall be developed in this project. Install manhole identification plates in a conspicuous place, facing towards the closest road. Stick identification plates with weather and UV-resistant adhesive.

3.2 FIELD QUALITY CONTROL: As an exception to requirements that may be stated elsewhere in the contract, notify the Contracting Officer 15 working days prior to each test.

Furnish labor, equipment, and incidentals required for testing, except that the Government will provide electric power required for the tests. Correct defects in the work provided by the Contractor and repeat tests until the work is in compliance with contract requirements.

3.2.1 Performance of Acceptance Checks and Tests: Perform in accordance with the manufacturer's recommendations. Include the following visual and mechanical inspections and electrical tests:

3.2.1.1 Low Voltage Cable Tests: Perform tests after wiring is completed, connected, and ready for operation, but prior to placing system in service and before any branch circuit breaker is closed.

a. Visual and Mechanical Inspection

(1) Inspect cables for physical damage and proper connection in accordance with contract plans and specifications.

(2) Test cable mechanical connections to manufacturer's recommended values using a calibrated torque wrench.

(3) Verify that cable bends are not less than manufacturer's minimum allowable bending radius.

(4) Verify that cable is supplied and connected in accordance with contract plans and specifications.

b. Electrical Tests:

(1) Perform insulation-resistance test on each conductor with respect to ground and adjacent conductor; minimum insulation-resistance values shall not be less than 2 megohms.

(2) Perform continuity test to insure proper cable connection.

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(3) Perform a shield continuity test on each power cable by ohmmeter method. Record ohms value, resistance values in excess of 10 ohms per 300 meters of cable must be investigated and justified.

3.2.1.2 Medium Voltage Cable Tests: Perform tests after installation of cable, splices, and terminators and before terminating to equipment or splicing to existing circuits.

a. Visual and Mechanical Inspection

(1) Inspect exposed cable sections for physical damage.

(2) Verify that cable is supplied and connected in accordance with contract plans and specifications.

(3) Inspect for proper shield grounding, cable support, and cable termination.

(4) Verify that cable bends are not less than manufacturer's minimum allowable bending radius

(5) Visually inspect jacket and insulation condition.

(6) Inspect for proper phase identification and arrangement.

b. Electrical Tests:

(1) Perform a shield continuity test on each power cable by ohmmeter method. Record ohms value, resistance values in excess of 10 ohms per 300 meters of cable must be investigated and justified.

3.2.1.3 Grounding System

a. Visual and Mechanical Inspection

(1) Inspect ground system for compliance with contract plans and specifications.

b. Electrical Tests:

(1) Perform ground-impedance measurements utilizing the fall-of-potential method. On systems consisting of interconnected ground rods, perform tests after interconnections are complete. On systems consisting of a single ground rod perform tests before any wire is connected. Take measurements in normally dry weather, not less than 48 hours after rainfall. Use a portable megohmmeter tester in accordance with manufacturer's instructions to test each ground or group of grounds. The

33 71 02-12 instrument shall be equipped with a meter reading directly in ohms or fractions thereof to indicate the ground value of the ground rod or grounding systems under test.

*** END OF SECTION ***