1、NEMA Standards PublicationNational Electrical Manufacturers AssociationNEMA FB 2.40-2016Installation Guidelines for Expansion and Expansion/Deflection Fittings 2016 National Electrical Manufacturers Association NEMA FB 2.40-2016 Installation Guidelines for Expansion and Expansion/Deflection Fittings
2、 Published by: National Electrical Manufacturers Association 1300 North 17th Street, Suite 900 Rosslyn, VA 22209 www.nema.org 2016 National Electrical Manufacturers Association. All rights, including translation into other languages, reserved under the Universal Copyright Convention, the Berne Conve
3、ntion for the Protection of Literary and Artistic Works, and the International and Pan American copyright conventions. 2016 National Electrical Manufacturers Association NOTICE AND DISCLAIMER The information in this publication was considered technically sound by a consensus among persons engaged in
4、 its development at the time it was approved. Consensus does not necessarily mean there was unanimous agreement among every person participating in the development process. The National Electrical Manufacturers Association (NEMA) standards and guideline publications, of which the document herein is
5、one, are developed through a voluntary standards development process. This process brings together volunteers and/or seeks out the views of persons who have an interest in the topic covered by this publication. Although NEMA administers the process and establishes rules to promote fairness in the de
6、velopment of consensus, it does not write the documents, nor does it independently test, evaluate, or verify the accuracy or completeness of any information or the soundness of any judgments contained in its standards and guideline publications. NEMA disclaims liability for any personal injury, prop
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8、eteness of any information published herein, and disclaims and makes no warranty that the information in this document will fulfill any particular purpose(s) or need(s). NEMA does not undertake to guarantee the performance of any individual manufacturers or sellers products or services by virtue of
9、this standard or guide. In publishing and making this document available, NEMA is not undertaking to render professional or other services for or on behalf of any person or entity, nor is NEMA undertaking to perform any duty owed by any person or entity to someone else. Anyone using this document sh
10、ould rely on his or her own independent judgment or, as appropriate, seek the advice of a competent professional in determining the exercise of reasonable care in any given circumstance. Information and other standards on the topic covered by this publication may be available from other sources, whi
11、ch the user may wish to consult for additional views or information not covered by this publication. NEMA has no power, nor does it undertake to police or enforce compliance with the contents of this document. NEMA does not certify, test, or inspect products, designs, or installations for safety or
12、health purposes. Any certification or other statement of compliance with any health- or safety-related information in this document shall not be attributable to NEMA and is solely the responsibility of the certifier or maker of the statement. NEMA FB 2.40-2016 Page i 2016 National Electrical Manufac
13、turers Association CONTENTS Foreword . iii Introduction . iv Section 1 General 1 1.1 Scope 1 1.2 Nomenclature and definitions 1 1.3 References 2 1.3.1 Standards and guidelines 2 1.3.2 Electrical codes . 3 Section 2 Seismic Issues . 4 Section 3 Hazardous Locations . 5 Section 4 Raceway Expansion Rela
14、tive to Building Materials . 6 Section 5 Installation 7 5.1 Aboveground . 7 5.1.1 Setting the piston. 7 5.1.2 Allowing travel for the raceway systems . 8 5.1.3 Expansion fitting placement 9 5.1.4 Expansion fittings in the vertical position 9 5.1.5 Wire inside conduit 9 5.2 Belowground . 9 5.2.1 Dire
15、ct burial . 9 5.2.2 Encased burial . 10 5.2.3 Temporary open trenches . 10 5.2.4 Building/structural joints 10 5.2.5 Wet and dry locations 11 5.2.6 Ground settlement . 11 5.2.7 Grounding/bonding 12 5.3 Mounting on live vegetation 12 Section 6 How Expansion and Expansion/Deflection Fittings Work . 13
16、 6.1 Description 13 6.2 Design . 13 6.2.1 Expansion and expansion/deflection fittings used with RMC, IMC or EMT 13 6.2.2 Expansion and expansion/deflection fittings used with RNC, RTRC, or ENT 14 Section 7 Using Expansion Fittings to Repair PVC and RTRC 15 7.1 General 15 7.2 Repair procedure 15 Sect
17、ion 8 Storage and Handling 18 8.1 Handling and storage of expansion and expansion/deflection fittings 18 8.2 Handling 18 8.3 Storage 18 8.4 Inventory rotation 18 Appendix A Relevant Standards . A-1 Appendix B Raceway Expansion Characteristics . B-1 B.1 Rigid polyvinyl chloride (PVC) conduit B-1 B.1.
18、1 Coefficient of thermal expansion . B-1 B.1.2 Calculation examples B-1 B.2 Reinforced thermosetting resin conduit (RTRC) . B-3 B.2.1 Coefficient of thermal expansion . B-3 B.2.2 Calculation of expansion allowance B-3 B.3 Metal conduit and tubing . B-3 B.3.1 Coefficient of thermal expansion . B-3 B.
19、3.2 Calculation of expansion allowance B-3 NEMA FB 2.40-2016 Page ii 2016 National Electrical Manufacturers Association FIGURES Figure 1 Cracking of conduit . 6 Figure 2 Conduit joints separated . 6 Figure 3 Piston settings . 7 Figure 4 Piston and barrel separation from improperly set piston 8 Figur
20、e 5 Improperly secured expansion fitting 8 Figure 6 Use of one or multiple expansion fittings 9 Figure 7 Expansion/deflection fittings . 10 Figure 8 Expansion/deflection fitting . 10 Figure 9 Structural joint . 11 Figure 10 Expansion/deflection fittings in bridge embankment 11 Figure 11 Example desi
21、gn for expansion fitting with RMS, IMT, or EMT . 13 Figure 12 Example design for expansion/deflection fitting used with RNC, IMC, or EMT 14 Figure 13 Example design, expansion fitting with RNC, RTRC, or ENT 14 Figure 14 Example design, expansion/deflection fitting with RNC, RTRC, or ENT 14 Figure 15
22、 Cutting damaged portion of raceway 15 Figure 16 Expansion fitting placement 16 Figure 17 Repair of larger raceway damage sections 16 Figure 18 Solvent cement or adhesive applied to replacement section and remaining raceway . 17 Figure 19 Completed raceway repair 17 Figure B-1 Setting of piston. B-3
23、 TABLES Table B-1 Expansion characteristics of rigid PVC conduit B-1 Table B-2 Expansion allowances for typical length of rigid PVC conduit . B-2 Table B-3 Expansion characteristics of reinforced thermosetting resin conduit (RTRC) B-4 Table B-4 Expansion characteristics of steel conduit and tubing .
24、 B-5 Table B-5 Expansion characteristics of aluminum conduit and tubing . B-5 NEMA FB 2.40-2016 Page iii 2016 National Electrical Manufacturers Association FOREWORD These guidelines were prepared by a joint sections committee of the Conduit Fittings (5FB), Steel Conduit and Electrical Metallic Tubin
25、g (5RN), and Polymer Raceway Products (5TC) sections of the National Electrical Manufacturers Association. At the time of approval, these sections consisted of the following members. Conduit Fittings Section: Adalet, a division of Scott FCleveland, OH AFC Cable Systems, a part of Atkore INew Bedford
26、, MA Appleton GRosemont, IL Arlington Industries, IScranton, PA Bridgeport Fittings, Inc. Stratford, CT Calpipe Industries, IDowney, CA Crouse-Hinds by Eatonwww.crouse-Syracuse, NY Eatons B-Line BHighland, IL ERICO, ISolon, OH Hubbell IShelton, CT IPEX USA LLCMississauga, ON, Canada Legrand North Am
27、ericawww.legrand.usWest Hartford, CT Producto Electric COrangeburg, NY Progressive Machine Die, Inc.www-pmd-Walton Hills, OH Sigma Electric Manufacturing CGarner, NC Steel Electric Products Company, Inc.www.sepco-Brooklyn, NY Thomas the Canadian Electrical Code(CE Code), Part I; the International Bu
28、ilding Code; and the National Building Code of Canada. These guidelines cover expansion and expansion/deflection fittings for nonflexible metallic and nonmetallic conduit and tubing, including the following: Electrical metallic tubing: type EMT Intermediate metal conduit: type IMC Reinforced thermos
29、etting resin conduit: type RTRC Rigid metal conduit: type RMC Rigid polyvinyl chloride conduit: type PVC 1.2 Nomenclature and definitions angular deflection: the degree that a straight run of raceway bends from its center line under a load barrel: a static component of an expansion fitting or expans
30、ion/deflection fitting that houses the piston coefficient of thermal expansion: the amount a raceway material expands or contracts per unit length with one degree change in temperature contraction: reduction in raceway length deflection: the displacement of a raceway under load deflection fitting: a
31、 raceway accessory that compensates for the offset or angular deflection of a raceway system delta temperature (delta T): the difference between the recorded maximum ambient temperature and minimum ambient temperature engagement line: see mid-point ring expansion: increase in raceway length expansio
32、n/deflection fitting: a raceway accessory that compensates for the linear expansion, linear contraction, and the offset or angular deflection of a raceway system expansion fitting: a raceway accessory that compensates for the linear expansion or contraction of a raceway system expansion joint: see s
33、tructural joint mid-point ring: a marking on an expansion fitting piston indicating the middle of the piston movement joint: see structural joint muzzle: see barrel offset: intentional or unintentional linear misalignment of a raceway system NEMA FB 2.40-2016 Page 2 2016 National Electrical Manufact
34、urers Association parallel deflection: two parallel raceways separated by an expansion/deflection fitting that are offset from their center lines parallel misalignment: see parallel deflection piston: a dynamic component of an expansion fitting or expansion/deflection fitting that inserts into the b
35、arrel raceway: an enclosed channel of metallic or nonmetallic materials designed expressly for the routing of wires or cables and the placement of busbars structure: a body or assemblage of components (such as a building, parking garage, or bridge) capable of supporting loads structural joint: a des
36、igned mechanical gap to compensate for movement within the structure due to wind, thermal expansion or contraction, vibrations, and other forces wet location: an installation that is a) underground or in concrete slabs or masonry in direct contact with earth; b) subject to saturation with water or o
37、ther liquids, such as vehicle washing areas; or c) exposed to weather 1.3 References Expansion and expansion/deflection fittings are required in the following referenced standards. 1.3.1 Standards and guidelines ANSI C80.1 Electrical Rigid Steel Conduit (ERSC) ANSI C80.3 Electrical Metallic Tubing (
38、EMT) ANSI C80.5 Electrical Rigid Aluminum Conduit (ERAC) ANSI C80.6 Electrical Intermediate Metal Conduit (EIMC) ASTM F512 Standard Specification for Smooth-wall Polyvinyl Chloride (PVC) Conduit and Fittings for Underground Installations NEMA RN 1 Polyvinyl Chloride (PVC) Externally Coated Galvanize
39、d Rigid Steel Conduit and Intermediate Metal Conduit NEMA RV 3 Application and Installation Guidelines for Flexible and Liquidtight Flexible Metal and Nonmetallic Conduits NEMA TC-2 Electrical Polyvinyl Chloride (PVC) Conduit NEMA TC-6 b) where subject to saturation with water and other liquids; and
40、 c) underground or in concrete slabs or masonry in direct contact with the earth. 5.2.6 Ground settlement The NEC considers ground settlement as “earth movement.” NEC300.5(J) states that where raceways are subject to earth movement by settlement or frost, they shall be arranged so as to prevent dama
41、ge to the enclosed conductors or to equipment connected to the raceway. Expansion fittings typically would not be required if the raceway is buried below the frost line or in an area where ground movement is not expected. However, if an expansion fitting is used and the raceway protrudes above the g
42、round surface, it is recommended to install the expansion fitting at the base of the service meter as the exposed raceway emerges from the ground to the meter. NEMA FB 2.40-2016 Page 12 2016 National Electrical Manufacturers Association 5.2.7 Grounding/bonding 5.2.7.1 Nonmetallic raceways Nonmetalli
43、c raceways require a separate equipment-grounding conductor when equipment grounding is required. The use of a nonmetallic expansion or expansion/deflection fitting does not change or add to this requirement. When a metal expansion or expansion/deflection fitting is used with a nonmetallic raceway,
44、the fitting is required to be bonded to the equipment grounding conductor. 5.2.7.2 Metal raceways Expansion or expansion/deflection fittings and telescoping sections of metal raceways shall be made electrically continuous, per NEC 300.10, by equipment bonding jumpers or other means, according to NEC
45、 250.98. This can be accomplished by using an expansion or expansion/deflection fitting that has an integral bonding conductor, using a bonding jumper attached to appropriate fittings on either side of the expansion or expansion/deflection fitting. 5.3 Mounting on live vegetation The NEC does not re
46、strict wiring methods to be mounted on live vegetation. Usually flexible raceways or cables are used in these applications. When rigid raceways are used, an expansion/deflection fitting should be used to account for vegetation growth, thermal expansion, and contraction and movement during weather co
47、nditions. Due to vegetation growth and environmental conditions, and erosion in the case of buried conduit, periodic re-inspection is recommended. NEMA FB 2.40-2016 Page 13 2016 National Electrical Manufacturers Association Section 6 How Expansion and Expansion/Deflection Fittings Work 6.1 Descripti
48、on Expansion and expansion/deflection fittings serve as a connection between two raceways to compensate for the thermal expansion and contraction, or movement in structural joints of buildings, bridges, parking garages, and/or other structures. 6.2 Design 6.2.1 Expansion and expansion/deflection fittings used with RMC, IMC or EMT Typical expansion and expansion/deflection fittings used with RMC, IMC, or EMT have the following components: a) malleable or ductile materials, with exterior and interior means of corrosion protection; b) a means of
