1、09-10 26 05 21 - 1 SECTION 26 05 21 LOW-VOLTAGE ELECTRICAL POWER CONDUCTORS AND CABLES (600 VOLTS AND BELOW) SPEC WRITER NOTE: Delete between /_/ if not applicable to project. Also delete any other item or paragraph not applicable to the section and renumber the paragraphs. PART 1 - GENERAL 1.1 DESC
2、RIPTION This section specifies the furnishing, installation, and connection of the low voltage power and lighting wiring. 1.2 RELATED WORK A. Section 07 84 00, FIRESTOPPING: Sealing around penetrations to maintain the integrity of fire-rated construction. B. Section 26 05 11, REQUIREMENTS FOR ELECTR
3、ICAL INSTALLATIONS: General electrical requirements that are common to more than one section. C. Section 26 05 26, GROUNDING AND BONDING FOR ELECTRICAL SYSTEMS: Requirements for personnel safety and to provide a low impedance path for possible ground fault currents. D. Section 26 05 33, RACEWAY AND
4、BOXES FOR ELECTRICAL SYSTEMS: Conduits for cables and wiring. E. Section 26 05 41, UNDERGROUND ELECTRICAL CONSTRUCTION: Installation of low-voltage conductors and cables in manholes and ducts. 1.3 QUALITY ASSURANCE Refer to Paragraph, QUALIFICATIONS, in Section 26 05 11, REQUIREMENTS FOR ELECTRICAL
5、INSTALLATIONS. 1.4 FACTORY TESTS Low voltage cables shall be thoroughly tested at the factory per NEMA WC-70 to ensure that there are no electrical defects. Factory tests shall be certified. 1.5 SUBMITTALS In accordance with Section 26 05 11, REQUIREMENTS FOR ELECTRICAL INSTALLATIONS, submit the fol
6、lowing: 1. Manufacturers Literature and Data: Showing each cable type and rating. 2. Certifications: Two weeks prior to the final inspection, submit four copies of the following certifications to the /Resident Engineer/ /COTR/: a. Certification by the manufacturer that the materials conform to the r
7、equirements of the drawings and specifications. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-09-10 26 05 21 - 2 b. Certification by the contractor that the materials have been properly installed, connected, and tested. 1.6 APPLICABLE PUBLICATIONS
8、A. Publications listed below (including amendments, addenda, revisions, supplements and errata) form a part of this specification to the extent referenced. Publications are reference in the text by designation only. B. American Society of Testing Material (ASTM): D2301-04 . Standard Specification fo
9、r Vinyl Chloride Plastic Pressure-Sensitive Electrical Insulating Tape C. National Fire Protection Association (NFPA): 70-08 National Electrical Code (NEC) D. National Electrical Manufacturers Association (NEMA): WC 70-09 . Power Cables Rated 2000 Volts or Less for the Distribution of Electrical Ene
10、rgy E. Underwriters Laboratories, Inc. (UL): 44-05 Thermoset-Insulated Wires and Cables 83-08 Thermoplastic-Insulated Wires and Cables 467-071 Electrical Grounding and Bonding Equipment 486A-486B-03 . Wire Connectors 486C-04 Splicing Wire Connectors 486D-05 Sealed Wire Connector Systems 486E-94 Equi
11、pment Wiring Terminals for Use with Aluminum and/or Copper Conductors 493-07 . Thermoplastic-Insulated Underground Feeder and Branch Circuit Cable 514B-04 Conduit, Tubing, and Cable Fittings 1479-03 Fire Tests of Through-Penetration Fire Stops PART 2 - PRODUCTS 2.1 CONDUCTORS AND CABLES A. Conductor
12、s and cables shall be in accordance with NEMA WC-70 and as specified herein. B. Single Conductor: 1. Shall be annealed copper. 2. Shall be stranded for sizes No. 8 AWG and larger, solid for sizes No. 10 AWG and smaller. 3. Shall be minimum size No. 12 AWG, except where smaller sizes are allowed here
13、in. C. Insulation: 1. XHHW-2 or THHN-THWN shall be in accordance with NEMA WC-70, UL 44, and UL 83. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-09-10 26 05 21 - 3 SPEC WRITER NOTE: Retain the paragraph below if these cables types are required for
14、 temporary installation of normal power. Other uses are not allowed. /2. Direct burial: UF or USE shall be in accordance with NEMA WC-70 and UL 493./ SPEC WRITER NOTE: VA no longer installs new isolated power systems, per VHA Directive 2008-011. Retain the paragraph below for work on existing system
15、s. /3. Isolated power system wiring: Type XHHW-2 with a dielectric constant of 3.5 or less./ D. Color Code: 1. Secondary service feeder and branch circuit conductors shall be color-coded as follows: 208/120 volt Phase 480/277 volt Black A Brown Red B Orange Blue C Yellow White Neutral Gray * * or wh
16、ite with colored (other than green) tracer. a. Lighting circuit “switch legs” and 3-way switch “traveling wires” shall have color coding that is unique and distinct (e.g., pink and purple) from the color coding indicated above. The unique color codes shall be solid and in accordance with the NEC. Co
17、ordinate color coding in the field with the /Resident Engineer/ /COTR/. 2. Use solid color insulation or solid color coating for No. 12 AWG and No. 10 AWG branch circuit phase, neutral, and ground conductors. 3. Conductors No. 8 AWG and larger shall be color-coded using one of the following methods:
18、 a. Solid color insulation or solid color coating. b. Stripes, bands, or hash marks of color specified above. c. Color as specified using 0.75 in 19 mm wide tape. Apply tape in half-overlapping turns for a minimum of 3 in 75 mm for terminal points, and in junction boxes, pull-boxes, troughs, and man
19、holes. Apply the last two laps of tape with no tension to prevent possible unwinding. Where cable markings are covered by tape, apply tags to cable, stating size and insulation type. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-09-10 26 05 21 - 4
20、4. For modifications and additions to existing wiring systems, color coding shall conform to the existing wiring system. /5. Color code for isolated power system wiring shall be in accordance with the NEC./ 2.2 SPLICES AND JOINTS A. In accordance with UL 486A, C, D, E, and NEC. B. Aboveground Circui
21、ts (No. 10 AWG and smaller): 1. Connectors: Solderless, screw-on, reusable pressure cable type, rated 600 V, 220 F 105 C, with integral insulation, approved for copper and aluminum conductors. 2. The integral insulator shall have a skirt to completely cover the stripped wires. 3. The number, size, a
22、nd combination of conductors, as listed on the manufacturers packaging, shall be strictly followed. C. Aboveground Circuits (No. 8 AWG and larger): 1. Connectors shall be indent, hex screw, or bolt clamp-type of high conductivity and corrosion-resistant material, listed for use with copper and alumi
23、num conductors. 2. Field-installed compression connectors for cable sizes 250 kcmil and larger shall have not fewer than two clamping elements or compression indents per wire. 3. Insulate splices and joints with materials approved for the particular use, location, voltage, and temperature. Splice an
24、d joint insulation level shall be not less than the insulation level of the conductors being joined. 4. Plastic electrical insulating tape: Per ASTM D2304, flame-retardant, cold and weather resistant. D. Underground Branch Circuits and Feeders: 1. Submersible connectors in accordance with UL 486D, r
25、ated 600 V, 190 F 90 C, with integral insulation. 2.3 CONTROL WIRING A. Unless otherwise specified elsewhere in these specifications, control wiring shall be as specified for power and lighting wiring, except that the minimum size shall be not less than No. 14 AWG. B. Control wiring shall be large e
26、nough such that the voltage drop under in-rush conditions does not adversely affect operation of the controls. 2.4 WIRE LUBRICATING COMPOUND A. Lubricating compound shall be suitable for the wire insulation and conduit, and shall not harden or become adhesive. /B. Shall not be used on wire for isola
27、ted-type electrical power systems./ Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-09-10 26 05 21 - 5 PART 3 - EXECUTION 3.1 GENERAL A. Install in accordance with the NEC, and as specified. B. Install all wiring in raceway systems. C. Splice cables
28、and wires only in outlet boxes, junction boxes, pull-boxes, manholes, or handholes. D. Wires of different systems (e.g., 120 V, 277 V) shall not be installed in the same conduit or junction box system. E. Install cable supports for all vertical feeders in accordance with the NEC. Provide split wedge
29、 type which firmly clamps each individual cable and tightens due to cable weight. F. For panel boards, cabinets, wireways, switches, and equipment assemblies, neatly form, train, and tie the cables in individual circuits. G. Seal cable and wire entering a building from underground between the wire a
30、nd conduit where the cable exits the conduit, with a non-hardening approved compound. H. Wire Pulling: 1. Provide installation equipment that will prevent the cutting or abrasion of insulation during pulling of cables. Use lubricants approved for the cable. 2. Use nonmetallic ropes for pulling feede
31、rs. 3. Attach pulling lines for feeders by means of either woven basket grips or pulling eyes attached directly to the conductors, as approved by the /Resident Engineer/ /COTR/. 4. All cables in a single conduit shall be pulled simultaneously. 5. Do not exceed manufacturers recommended maximum pulli
32、ng tensions and sidewall pressure values. I. No more than three single-phase branch circuits shall be installed in any one conduit. 3.2 INSTALLATION IN MANHOLES A. Install and support cables in manholes on the steel racks with porcelain or equivalent insulators. Train the cables around the manhole w
33、alls, but do not bend to a radius less than six times the overall cable diameter. SPEC WRITER NOTE: Remove the paragraph below if not required for the project. /B. Fireproofing: 1. Install fireproofing on low-voltage cables where the low-voltage cables are installed in the same manholes with medium-
34、voltage cables; also cover the low-voltage cables with arcproof and fireproof tape. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-09-10 26 05 21 - 6 2. Use tape of the same type used for the medium-voltage cables, and apply the tape in a single lay
35、er, half-lapped, or as recommended by the manufacturer. Install the tape with the coated side towards the cable and extend it not less than 1 in 25 mm into each duct. 3. Secure the tape in place by a random wrap of glass cloth tape./ 3.3 SPLICE INSTALLATION A. Splices and terminations shall be mecha
36、nically and electrically secure. B. Tighten electrical connectors and terminals according to manufacturers published torque values. C. Where the Government determines that unsatisfactory splices or terminations have been installed, remove the devices and install approved devices at no additional cos
37、t to the Government. 3.4 FEEDER IDENTIFICATION A. In each interior pull-box and junction box, install metal tags on all circuit cables and wires to clearly designate their circuit identification and voltage. The tags shall be the embossed brass type, 1.5 in 40 mm in diameter and 40 mils thick. Attac
38、h tags with plastic ties. B. In each manhole and handhole, provide tags of the embossed brass type, showing the circuit identification and voltage. The tags shall be the embossed brass type, 1.5 in 40 mm in diameter and 40 mils thick. Attach tags with plastic ties. 3.5 EXISTING WIRING Unless specifi
39、cally indicated on the plans, existing wiring shall not be reused for a new installation. 3.6 CONTROL AND SIGNAL WIRING INSTALLATION A. Unless otherwise specified in other sections, install wiring and connect to equipment/devices to perform the required functions as shown and specified. SPEC WRITER
40、NOTE: Each separate system shall have a dedicated power supply circuit. B. Except where otherwise required, install a separate power supply circuit for each system so that malfunctions in any system will not affect other systems. C. Where separate power supply circuits are not shown, connect the sys
41、tems to the nearest panel boards of suitable voltages, which are intended to supply such systems and have suitable spare circuit breakers or space for installation. 3.7 CONTROL AND SIGNAL SYSTEM WIRING IDENTIFICATION A. Install a permanent wire marker on each wire at each termination. Provided by IH
42、SNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-09-10 26 05 21 - 7 B. Identifying numbers and letters on the wire markers shall correspond to those on the wiring diagrams used for installing the systems. C. Wire markers shall retain their markings after cleaning.
43、D. In each manhole and handhole, install embossed brass tags to identify the system served and function. SPEC WRITER NOTE: Retain the paragraph below if direct burial cables are required for temporary installation of normal power. Other uses are not allowed. /3.8 DIRECT BURIAL CABLE INSTALLATION A.
44、Tops of the cables: 1. Below the finished grade: Minimum 24 in 600 mm unless greater depth is shown. 2. Below road and other pavement surfaces: In conduit as specified, minimum 30 in 750 mm unless greater depth is shown. 3. Do not install cables under railroad tracks. B. Under road and paved surface
45、s: Install cables in concrete-encased galvanized steel rigid conduits. Size as shown on plans, but not less than 2 in 50 mm trade size with bushings at each end of each conduit run. Provide size/quantity of conduits required to accommodate cables plus one spare. C. Work with extreme care near existi
46、ng ducts, conduits, cables, and other utilities to prevent any damage. D. Cut the trenches neatly and uniformly: 1. Excavating and backfilling is specified in Section 31 20 00, EARTH MOVING. 2. Place a 3 in 75 mm layer of sand in the trenches before installing the cables. 3. Place a 3 in 75 mm layer
47、 of sand over the installed cables. 4. Install continuous horizontal, 1 in x 8 in 25 mm x 200 mm preservative impregnated wood planking 3 in 75 mm above the cables before backfilling. E. Provide horizontal slack in the cables for contraction during cold weather. F. Install the cables in continuous l
48、engths. Splices within cable runs shall not be accepted. G. Connections and terminations shall be listed submersible-type designed for the cables being installed. H. Warning tape shall be continuously placed 12 in 300 mm above the buried cables./ Provided by IHSNot for ResaleNo reproduction or netwo
49、rking permitted without license from IHS-,-,-09-10 26 05 21 - 8 3.9 ACCEPTANCE CHECKS AND TESTS A. Feeders and branch circuits shall have their insulation tested after installation and before connection to utilization devices, such as fixtures, motors, or appliances. Test each conductor with respect to adjacent conductors and
