1、Recommended Practice forInstalling UndergroundNonmetallic Utility DuctNECA 605-2004AMERICAN NATIONAL STANDARDPublished byNational Electrical Contractors AssociationJointly developed withNational Electrical Manufacturers AssociationTRecommended Practice forInstalling UndergroundNonmetallic Utility Du
2、ctNECA/NEMA 605-2005An AmericanNational StandardJointly developed withNational Electrical Manufacturers AssociationPublished byNational Electrical Contractors Associationiii a73Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3、. . . . .v1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12. Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 3. Types of Duct
4、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33.1 Duct Designed for Encasement in Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33.2 Duct Designed for Direct Burial . . .
5、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33.3 Duct Designed for Concrete Encasement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34. Duct Separations . . . . . . . . . . . . . . . . .
6、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44.1 Duct Spacers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44.2 Power Duct Banks . . . . . . . . . . . . . . . . . . .
7、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44.3 Communication Duct Banks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44.4 Combined Power and Communications Duct . . . . . . .
8、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44.5 Considerations for Specifiers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45. Handling and Storage of Nonmetallic Ducts . . . . . . . . . . . . . .
9、 . . . . . . . . . . . . . . . . . . . . . .55.1 Transportation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55.2 Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55.3 Handling on the Jobsite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66. Trenching Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . .
11、 . . . . . . . . . . . . . . . . . . . . . . . . . .76.1 Proper Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76.2 Trench Excavation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76.3 Trenchless Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87. Joining Nonmetallic Ducts . . . . . . . . . . . . . . . . . . . . . . . .
13、 . . . . . . . . . . . . . . . . . . . . . . . . . .97.1 Types of Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .97.2 Recommended Joining Procedures . . . . . . . . . . . . . . . . . . . . . . . . . .
14、. . . . . . . . . . . . . . . . . . . . . . . . . . .118. Concrete Encasement of Nonmetallic Ducts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .148.1 Duct Layering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15、. . . . . . . . . . . . . .148.2 Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .158.3 Anchoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16、. . . . . . . . . . . . . . . . . . . . . . . .15 8.4 Concrete Pour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 8.5 Backfilling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .169. Direct Burial of Nonmetallic Ducts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .179.1 Duct Layering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18、. . . . . . . . . . . . . . . . . . . . . . . . . . .179.2 Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .179.3 Bends or Grade Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179.4 Duct Embedment and Final Backfill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .179.5 Compacting Backfill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
20、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18Table of Contents10. Field Bending . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1911. Short-Radius Bends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
21、. . . . . . . . . . . . . . . . . . . . . . .2012. Repairing Nonmetallic Ducts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .217.1 PVC and RTRC Ducts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
22、 . . . . . . . . . . .217.2 PE Ducts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2213. Connections to Other Duct Systems of Other Materials . . . . . . . . . . . . . . . . . . . . . . . . . . .2314
23、. Duct Rodding (Fishing) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2415. Mandrelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25Annex A: Field-Bending Procedures . .
24、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27Annex B: Conduit-in-Casing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31Annex C: Installation Instructions for RTRC Joints . . . . . . . . . . . . . .
25、. . . . . . . . . . . . . . . . . . . . .34 Annex D: Reference Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36NECA/NEMA 605 Recommended Practice for Installing Underground Nonmetallic Utility Ducta73 ivv a73National Electrical Installati
26、on Standardsare intend-ed to improve communication among specifiers, pur-chasers, and suppliers of electrical construction ser-vices. They define a minimum baseline of qualityand workmanship for installing electrical productsand systems. NEISare intended to be referenced incontract documents for ele
27、ctrical construction pro-jects. The following language is recommended:Grounding and bonding should be performed inaccordance with NECA/NEMA 605-2005,Recommended Practice for InstallingUnderground Nonmetallic Utility Duct (ANSI).NECA/NEMA 605 is an adoption of NEMA TCB2-2000, NEMA Guidelines for the
28、Selection ofUnderground Nonmetallic Duct. The complete text ofNEMAs publication is reproduced here, in thisNational Electrical Installation Standard.Use of NEIS is voluntary, and the National ElectricalContractors Association assumes no obligation or lia-bility to users of this publication. Existenc
29、e of astandard shall not preclude any member or non-member of NECA from specifying or using alternateconstruction methods permitted by applicable regu-lations.This publication is intended to comply with the edi-tion of the National Electrical Code (NEC) in effectat the time of publication. Because t
30、hey are qualitystandards, NEIS may in some instances go beyondthe minimum requirements of the NEC. It is theresponsibility of users of this publication to complywith state and local electrical codes when installingelectrical products and systems.Suggestions for revisions and improvements to thisstan
31、dard are welcome. They should be addressed to:NECA Standards details on storage, handling, and installation are cov-ered in NEMA Bulletin No. TCB-3b) PVC DB duct meeting NEMA TC-6 follow manufacturers instruc-tions.Three methods are used for heat fusion joining ofplain-ended HDPE duct:1. Butt fusion
32、 type joint2. Socket-type couplings fused externally to theduct 3. Electrofusion. (This joining method is notsuitable to HDPE with corrugated outer walls.)7.1.6 Heat Shrink JointsThis joining method is used to join polyethylene ductto other types of duct materials. It uses a heat-shrinkable polyethy
33、lene sleeve.NECA/NEMA 605 Recommended Practice for Installing Underground Nonmetallic Utility Ducta73 10DA DSOCKET PLAIN ENDFigure 8. Adhesive Type JointFigure 9. Threaded JointJoining Nonmetallic Ducts11 a737.1.7 Adhesive JointsThere are adhesives available to provide watertightconnections.7.1.8 Ga
34、sketed JointsThere are a variety of gasketed joints available thatutilize elastomeric seals to provide watertight con-nections.7.1.9 Mechanical JointsThere are a variety of mechanical joints that utilizedevices such as friction fits, compression joints, andbolt-on couplings. Follow manufacturers ins
35、tructions.7.2 Recommended Joining Procedures7.2.1 Cutting DuctCut duct square with a hand saw, power saw, orrotary cutter. Remove the burrs left by sawing andthe ridges left by the rotary cutter with a knife or file.Break all sharp edges on the OD and ID of the cutwith a knife, file, or other beveli
36、ng tool to preventpossible damage to hands during handling and toprevent damage to cable coverings during subsequentcable pulls. Additionally, if the burrs and ridges arenot removed, an inferior joint may result.7.2.2 Cleaning Joint SurfacesSurfaces to be joined should be clean and free fromdirt, fo
37、reign materials and moisture. Clean the out-side surface of the duct spigot (for the depth of thesocket), and the inside surface of the socket with aclean dry cloth.7.2.3 Solvent Cement Jointsa) Selection of Solvent Cement Use solvent cement specified by the manufac-turer of the PVC raceway.b) Preca
38、utions for Handling Cement The solvents used in these cements are flam-mable. Their fumes can be harmful if adequateventilation is not provided. Use forced ventilation systems when cement-ing joints or fittings in confined spaces such asunventilated underground vaults or in small,enclosed areas. Do
39、not expose cements open flames, exposedheating elements, or sparks. Dont smoke whensolvent cementing joints. READ AND OBSERVE THE WARNINGSAND CAUTIONS CLEARLY STATED ON THELABELS OF SOLVENT CEMENT CONTAIN-ERS AND THE MATERIAL SAFETY DATASHEETS (MSDS).c) Brush SelectionApply cements with a natural br
40、istle or nylon brushor applicator of appropriate size to easily and rapidlycoat the surfaces to be joined. As a guide, use a brushwidth at least half the nominal duct size.d) Applying Cement and Joining Solvent cements are fast drying and should beapplied as quickly as possible consistent withgood w
41、orkmanship.Figure 10. Cutting Duct Apply a heavy, even coating of cement to theduct spigot outer surface, equal to the length ofthe duct socket. Immediately, while the spigot surface is stillwet with cement, insert the duct spigot with aslight twisting motion into the socket until itbottoms home at
42、the socket shoulder. Do nottwist or turn the duct after it has bottomed onthe shoulder. The slight twisting motion usedduring insertion helps to distribute the cementevenly, but if twisted after bottoming, the initialbond could be impaired. Assembly of a cemented joint should be com-pleted within 15
43、 seconds after application ofcement. Initial bonding begins immediatelywhen the cement coated joint surfaces are inposition. If there is any sign of drying of the cementsurfaces prior to assembly, recoat the duct spigotwith a fresh coat of cement and immediatelyinsert the duct spigot into the socket
44、 with atwisting motion. After assembly, wipe excess cement from theduct at the end of the socket, both for goodwork-manship and to prevent excessive cementfrom drip-ping on and possibly weakening thelower ducts. Cure times are affected by temperature andhumidity conditions. Consult manufacturersinst
45、ructions for specific recommendations.7.2.4 Threaded JointsScrew the mating threaded parts together, hand tight,and then tighten one additional turn using strapwrenches. If the joint is intended to be taken apartand reassembled several times during its service life,wrap the male threads with one lay
46、er of pipe threadtape. This allows easy disassembly and prevents pos-sible thread galling when tightened. (For RTRC dou-ble lead threads, refer to Annex D.)7.2.5 Heat Fusion JointsMake heat fusion joints in accordance with manufac-turers recommendations.7.2.6 Heat Shrink Jointsa) Place the sleeve ov
47、er the sections being joined.Keep the sleeve centered over the joint.b) Using a hot air heat source and working from oneend of the joint, move the heat source around thesleeve and towards the opposite end. Avoid concen-trating the heat in one spot. Apply heat until sleeveshrinks snugly around joint
48、assembly.c) The coupling has left and right hand threads so itcan thread onto both duct ends simultaneously. Notethe orientation of the thread pattern. Apply a smallamount of cable lubricant to the inside of the cou-pling. It is useful to make the thread cutting easier.d) Bring both ends of the duct
49、 into the coupling.Forcing the duct ends toward one another, begin torotate the coupling. Use wrenches to complete instal-lation. Do not overtighten. It will result in a signifi-cant reduction of the pull-out resistance.e.) Be certain that the coupling is threading ontoboth ends of the duct. Both ends should meet in thecenter of the coupling. This is necessary to obtainthe maximum resistance to pull out. If the couplingis not threading on equally, unscrew and restart thethreading operation.7.2.7 Adhesive Joints-See Annex C.7.2.8 Gasketed JointsBecause of the varie
