1、NECA/NCSCB 600-2014 Standard for Installing and Maintaining Medium-Voltage Cable NECA/NCSCB 600-2014 Standard for Installing and Maintaining Medium-Voltage Cable An American National Standard Published by National Electrical Contractors Association Jointly developed with National Cable Splicing Cert
2、ification Board (NCSCB) 1a:Bmc. National Cable Splicing Certification - -Revision History NECA/MACSCB 600-2003 02/2003 NECA/NCSCB 600-2014 08/2014 NOTICE OF COPYRIGHT This document is copyrighted by NECA Reproduction of these documents either in hard copy or soft (including posting on the web) is pr
3、ohibited without copyright permission. For copyright permission to reproduce portions of this document, please contact NECA Standards 4550 kg (10,000 lbs) for multiple conductors; manufacturers recommended maximum pulling tension; or manufacturers maximum sidewall pressure, whichever is least. Use p
4、ulling eyes and cable grips together for cables with nonmetallic sheaths, to prevent damage to the cable structure. Arrange cable grips such that the stress of pulling is applied to the conductor and not to the jacket or the insulation. Standard for Installing and Maintaining Medium-Voltage Cable NE
5、CA/NCSCB 600 Do not pull cables using metallic shielding wires, tapes or braids, or armor not designed for the purpose. Do not use rope hitches for pulling attachment to cables. Install a tension gauge at the pulling end during cable installation to measure cable pulling tensions. Continuously monit
6、or pulling tensions to ensure that maximum pulling tension is not exceeded. Permanently record cable pulling tension for each pull and submit to the engineer of record. Provide mechanical equipment or adequate personnel to feed cables into conduits or ducts to minimize cable pulling tension at the p
7、oint of feed. Ensure that cables do not cross over one another at the feed end during the pull. Where possible, feed cable into the end of the conduit or duct system closest to the greatest degree of bends, and pull from the other end. Where possible, pull cable downhill from higher elevations towar
8、d lower elevations. Ensure sidewall pressure is not exceeded when cables are pulled down vertically around a conduit bend. Observe cable at all points of duct entry and exit during pulling operation. Use two-way voice communication before and during installation. Stop pulling operation immediately w
9、ith any indication of binding or obstruction. Do not resume pulling until such difficulty is corrected. Test, terminate and energize cable as soon as possible after installation. If cables are left overnight or more than 8 hours after pulling prior to termination, remove the pulling attachment, cut
10、the cable end, reseal the cable immediately with tape, paraffin, or shrink wrap caps, and support the cable in a manner which will prevent entrance of moisture into the cable. When sealing cables with tape, completely wrap cable end with rubber tape to 75 mm (3 in.) from the cable end. Cover rubber
11、tape with polyvinylchloride tape. 5.8 Manholes Support cable reels on sturdy supports located sufficiently near the manhole to permit feeding the cable through the manhole opening without rubbing on the ground. Locate cable reels at the side of the manhole opening above the duct to receive the cable
12、. Install a flexible tube guide through the manhole opening in a manner that will prevent the cable from rubbing on the edges of the manhole frame, chimney, or duct. Consider delaying installation of manhole roofs in new construction to facilitate cable installation. Leave sufficient cable lengths i
13、n manholes to permit splicing and training on racks around the manhole walls, and for free movement of the cable due to expansion or contraction after installation. Overlap cable ends to provide sufficient undamaged cable for splicing. Overlap each cable to be spliced in manholes at the center line
14、of the proposed splice by a minimum of 600 mm (2 ft). 5.9 Direct Burial Install shielded cable specifically listed for direct burial. Locate structures in the path of the planned cable route, as much as practical, prior to trenching, plowing, or boring operations. For other underground utility facil
15、ities, contact the local underground facilities protective organization. Install cable in as straight and direct a line as practical with sufficient slack to allow for earth movement due to settling, freezing, and drying. Locate and route direct buried cables so as to be subject to the least disturb
16、ance practical and to allow safe access for construction, inspection, and maintenance. Bend cable to a sufficiently large radius to limit the likelihood of damage during installation. Avoid routes through unstable soil such as mud, shifting soils, corrosive soils, or other natural hazards. Install s
17、uitably protected cables when subjected to natural hazards. 13 NECA/NCSCB 600 Standard for Install ing and Maintaining Medium-Voltage Cable Use watertight taps and splices that are protected from mechanical damage. Direct burial cables are permitted to be spliced or tapped without the use of splice
18、boxes, provided they are installed using materials suitable for the application. Ensure that cables are properly bedded above and below prior to installing backfill. Use granular or selected backfill material or sleeves for suitable heat dissipation and physical protection of cables. Do not place la
19、rge rocks, paving materials, cinders, large or sharp angular substances, or corrosive materials in an excavation where materials can damage cables or other substructures, or prevent adequate compaction of backfill, or contribute to corrosion of cables. 5.9.1 Separations Do not install cables running
20、 parallel over or under other subsurface structures. Consult other underground facility owners for requirements of perpendicular crossings. Maintain a minimum of300 mm (12 in.) of horizontal and vertical separation between direct burial cable and other underground structures during installation, unl
21、ess all responsible parties for affected structures and utilities agree to a lesser separation. Refer to the NEC for greater clearance requirements in particular applications such as installing medium-voltage cables in hazardous (classified) locations, near swimming pools, and near underground fuel
22、storage facilities. Support underground structures to prevent transfer of harmful loads to the cable system where cables cross under another underground structure where a 300 mm (12 in.) vertical separation cannot be maintained. Support cables to prevent transfer of harmful loads to another undergro
23、und structure where cables cross over the structure where a 300 mm (12 in.) vertical separation cannot be maintained. Provide a minimum of 100 mm (4 in.) of tamped earth where cables cross other cables or piping where a 300 mm (12 in.) vertical separation cannot be maintained. 14 Provide suitable th
24、ermal barriers to prevent thermal damage where a 300 mm (12 in.) separation cannot be maintained between cables and other underground structures such as steam or cryogenic lines. 5.9.2 Burial Depth Install direct burial cable below the frost line and at a depth sufficient to protect the cable from d
25、amage imposed by expected surface usage. Refer to the National Electrical Code for minimum cover requirements. Lesser depth may be used where supplemental protection is provided. The supplemental protection shall be sufficient to protect the cable from damage imposed by expected surface usage. Where
26、 the surface under which a cable is to be installed is not final grade, locate the cable to meet or exceed the minimum cover requirements, both at the time of installation and thereafter. 5.9.3 MC Cable Do not install MC cable where exposed to destructive or corrosive conditions, such as direct buri
27、al in earth, in concrete, or where exposed to cinder fills or corrosive soils, unless the metallic sheath is suitable for the conditions or is protected by a material suitable for the conditions. 5.9.4 Nonmetallic Underground Conduit with Conductors (NUCC) Make bends of nonmetallic underground condu
28、it with conductors manually to prevent conduit damage and reduction of the internal conduit diameter. 5.9.5 Trenching Ensure that the bottom of the trench receiving direct-buried cable is relatively smooth, undisturbed earth, well-tamped earth, or sand. Sand beds shall be clean, leveled and tamped,
29、and from 75 mm (3 in.) to 150 mm (6 in.) thick. When trenching in rock or in rocky soil, provide bed of smooth, well-tamped, screened, rock-free backfill a minimum of 100 mm ( 4 in.) thick. Standard for Install ing and Maintaining Medium-Voltage Cable NECA/NCSCB 600 Provide compacted protective back
30、fill over cables. Backfill shall be free of materials that may damage the cable. Backfill shall consist of a 100 mm (4 in.) layer of sand or rock-free, sandy loam above the cable, and rock-free soil placed in 150 mm (6 in.) layers and mechanically tamped. Do not use machine compaction within 150 mm
31、(6 in.) of cables. Provide and install a metallic-backed “buried cable“ warning tape 300 mm (12 in.) to 450 mm (18 in.) below final grade in the middle of the trench. 5.9.6 Plowing Plowing in of cable in soil containing rock or other solid material shall be done in such a manner that solid materials
32、 will not damage the cable during the plowing operation or after installation. Use cable-plowing equipment and plowing-in methods designed such that the cable will not be damaged by bending, sidewall pressure, or excessive cable tension. 5.9.7 Boring Provide adequate physical protection of cables wh
33、ere soil and surface loading conditions are such that solid materials may damage the cable. 5.1 0 Training Cables Provide bending radii greater than the manufacturers recommended minimum to allow cable movement and flexing in manholes. When training cables, form bends with a smooth radius not smalle
34、r than the minimum radius. Do not train bending radii less than 12 times the outside cable diameter for shielded cable, or less than 8 times the outside cable diameter for non-shielded cable. Install and secure cables to allow cable movement without destructive concentration of stresses. Use suitabl
35、e tools for training cables into final position without damage. Do not use conduit hickeys for training cables. Route cables within switchgear, equipment, junction boxes, manholes, vaults, and similar locations in a manner which will allow adequate room and working space for bending, terminating, an
36、d splicing cables. Secure cables in a manner that will not result in the weight of the cable being placed on terminations or splices. Support cable in a manner that does not force cable against grounded metal or which compresses the cable diameter. Where cables are looped around a manhole interior,
37、provide a minimum of 360 degrees of cable loop. Where cables are not to be looped in manholes, route cables around manhole walls with the longest distance between points of entry and exit to provide slack for future cable repairs or splice replacement, if necessary. Train cables to closely parallel
38、walls in manholes, handholes, pull boxes, junction boxes, vaults, and similar locations, and to prevent interference with duct entrances or other cables. Provide appropriate insulating barriers where exposed live parts are in an enclosure. Where cables enter the top of enclosures, form a drip loop t
39、o prevent moisture from running down the cables onto terminations. 15 6. Splices and Terminations Preparation and installation instructions specific to cable manufacturers and termination and splice kits take precedence over instructions contained in this document. 6.1 General Terminate and splice c
40、ables in accordance with manufacturer instructions using approved materials, tools, and methods. Review design documents and the manufacturers instructions prior to starting work. Plan ahead to ensure that all materials and tools are available for use when needed. Ensure tools are in good condition
41、and are clean, dry, and sharp. Check splice and termination kits and materials to ensure that contents are complete. Inspect tapes, splice or termination kits, and manufactured components and parts for deterioration and damage. Do not install deteriorated or damaged materials. Ensure that all materi
42、als are compatible with cables, meet or exceed physical and electrical characteristics of cables, and are suitable for application in the environment. Use connectors capable of carrying the full-rated load, emergency overload, and fault currents without overheating. Use connectors and terminals of a
43、 material compatible with the conductors. Connect copper conductors to aluminum conductors using suitable, Listed connectors. Complete each termination and splice in one continuous work period to minimize cable exposure to the atmosphere. Ensure that all components required to complete terminations
44、and splices, along with detailed manufacturer instructions, are on hand prior to beginning work. 16 Provide suitable temporary lighting in the work area, along with power for electric soldering irons, hot plates, space heaters, fans, blowers, and other appliances, as needed. Terminate non-shielded c
45、ables operating at 5 kV and less using a thermal (welded or soldered) or pressure (compression or indent) lug, and either tape, heat shrink, or cold shrink tubing, and sealants. Apply tape over the lower portion of the lug barrel and down onto the cable insulation. Terminate all shielded cables oper
46、ating at 5 kV and more with stress relief tapes, tubes, or cones. Splicing and terminating shielded cable entails reconstructing the cable structure at splices and terminations. Strictly comply with manufacturers instructions. Use Class 3 terminations only in weather-protected areas. Do not use meta
47、l oxide sandpaper to prepare cables. Provide termination lugs that match equipment termination pads. Use appropriate spacers when more than one cable is installed on an equipment termination pad. Do not place cable lugs back-to hack on the equipment termination pad unless the equipment is suitably d
48、esigned or listed. Install anti tracking tape or boots on all shielded terminations. Bolt lugs to equipment termination pads using corrosion resistant bolts, nuts, and washers. Use aluminum or stainless steel hardware and Belleville washers for bolting aluminum-to-aluminum, and silicon bronze or sta
49、inless steel hardware and lock washers for bolting copper-to-copper or copper-to-aluminum, or as recommended by the manufacturers. Install Belleville and lock washers on the lug side. Torque terminations to manufacturers recommended torque values. Standard for Installing and Maintaining Medium-Voltage Cable NECA/NCSCB 600 Support cable splices in manholes on cable racks on both sides of the splice within 600 mm (24 in.) of the splice. Stagger multiple cable splices horizontally. Install splices with adequate clearances for original installation and future repair or replacement,
