1、NEMA Standards PublicationNational Electrical Manufacturers AssociationNEMA FB 2.10-2013Selection and Installation Guidelines For Fittings for Use With Non-Flexible Metallic Conduit or Tubing (Rigid Metal Conduit, Intermediate Metal Conduit, and Electrical Metallic Tubing)NEMA FB 2.10- 2013 Selectio
2、n and Installation Guidelines For Fittings for Use With Non-Flexible Metallic Conduit or Tubing (Rigid Metal Conduit, Intermediate Metal Conduit, and Electrical Metallic Tubing) Published by: National Electrical Manufacturers Association 1300 North 17th Street, Suite 900 Rosslyn, VA 22209 www.nema.o
3、rg Copyright 2013 by the National Electrical Manufacturers Association. All rights including translation into other languages, reserved under the Universal copyright Convention, the Berne Convention for the Protection of Literary and Artistic Works, and the International and Pan American Copyright C
4、onventions. 2013 National Electrical Manufacturers Association NOTICE AND DISCLAIMER The information in this publication was considered technically sound by the consensus of persons engaged in the development and approval of the document at the time it was developed. Consensus does not necessarily m
5、ean that there is unanimous agreement among every person participating in the development of this document. The National Electrical Manufacturers Association (NEMA) standards and guideline publications, of which the document contained herein is one, are developed through a voluntary consensus standa
6、rds 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. While NEMA administers the process and establishes rules to promote fairness in the development of consensus, it does not write the do
7、cument and it does not 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, property, or other damages of any nature whatsoeve
8、r, whether special, indirect, consequential, or compensatory, directly or indirectly resulting from the publication, use of, application, or reliance on this document. NEMA disclaims and makes no guaranty or warranty, expressed or implied, as to the accuracy or completeness of any information publis
9、hed herein, and disclaims and makes no warranty that the information in this document will fulfill any of your particular purposes or needs. NEMA does not undertake to guarantee the performance of any individual manufacturer or sellers products or services by virtue of this standard or guide. In pub
10、lishing 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 should rely on his or her own in
11、dependent judgment or, as appropriate, seek the advice of a competent professional in determining the exercise of reasonable care in any given circumstances. Information and other standards on the topic covered by this publication may be available from other sources, which the user may wish to consu
12、lt 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 health purposes. Any certific
13、ation or other statement of compliance with any health or safetyrelated information in this document shall not be attributable to NEMA and is solely the responsibility of the certifier or maker of the statement. FB 2.10-2013 Page i 2013 National Electrical Manufacturers Association CONTENTS Page For
14、eword . iii Introduction . iv Product Standards and Installation Codes . v Section 1 FITTINGS FOR USE WITH ELECTRICAL METALLIC TUBING (EMT) 1.1 Fitting Selection1 1.1.1 Fittings for EMT for Use in Wet Locations .2 1.1.2 Concrete-Tight Type Fittings for EMT 2 1.1.3 Expansion Fittings 2 1.2 Required M
15、arking 2 1.2.1 EMT Size and Material Type 3 1.2.2 Application Environment 3 1.3 Grounding 3 1.4 Raceway Preparation and Fitting Assembly Technique .4 1.4.1 Tightening Torque .4 1.4.2 Concrete-Tight Type Fittings 5 1.5 Attachment to Boxes and Support 5 1.5.1 Attachment to Threaded Entries .6 1.6 Veri
16、fication of Installation .6 Section 2 FITTINGS FOR USE WITH RIGID METAL CONDUIT AND INTERMEDIATE METAL CONDUIT 2.1 Fitting Selection 10 2.1.1 Fittings for Rigid and Intermediate Metal Conduit for Use in Wet Locations. 11 FB 2.10- 2013 Page ii 2013 National Electrical Manufacturers Association 2.1.2
17、Concrete-Tight Type Fittings for Rigid Metal Conduit and Intermediate Metal Conduit 12 2.1.3 Expansion Fittings 12 2.1.4 Conduit Bodies 12 2.2 Required Marking 12 2.2.1 Conduit Size and Material Type 12 2.2.2 Application Environment 13 2.3 Grounding 13 2.4 Raceway Preparation and Fitting Assembly Te
18、chnique . 13 2.4.1 Threadless Fittings . 13 2.4.2 Tightening Torque . 14 2.4.3 Concrete-Tight Type Fittings 14 2.4.4 Threaded Fittings for Threaded Conduit . 15 2.5 Attachment to Boxes and Support 15 2.6 Attachment to Threaded Entries . 16 2.7 Verification of Installation . 16 TABLES Table 1-1 TRADE
19、 SIZES AND METRIC DESIGNATORS FOR EMT6 Table 1-2 TIGHTENING TORQUE OF EMT FITTINGS .7 Table 2-1 TRADE SIZES AND METRIC DESIGNATORS FOR RIGID METAL CONDUIT AND IMC. 17 Table 2-2 TIGHTENING TORQUE FOR RMC AND IMC FITTINGS 17 FIGURES Figure 1-1 TYPICAL ELECTRICAL METALLIC TUBING FITTING DESIGNS 8 Figur
20、e 1-2 TYPICAL SUPPORTS FOR EMT9 Figure 2-1 TYPICAL RMC AND IMC FITTING DESIGNS . 18 Figure 2-2 TYPICAL THREADED CONDUIT ENTRIES 20 FB 2.10-2013 Page iii 2013 National Electrical Manufacturers Association Figure 2-3 TYPICAL SUPPORTS FOR RMC AND IMC. 21 Appendix A Conduit Body Conductor Fill . A-1 FB
21、2.10- 2013 Page iv 2013 National Electrical Manufacturers Association Foreword These selection and installation guidelines offer practical information on correct product selection and industry recommended practices for the installation of fittings for nonflexible metallic conduit or tubing in accord
22、ance with the National Electrical Code. These guidelines have been developed by the NEMA Conduit Fittings Section, which periodically reviews them for any revisions necessary to address changing conditions, product listing and installation requirements, and technical progress. Comments for proposed
23、revisions are welcomed and should be submitted to: Senior Vice President, Operations National Electrical Manufacturers Association 1300 North 17th Street Rosslyn, VA 22209 At the time of approval, the Conduit Fittings Section of the National Electrical Manufacturers Association had the following mem
24、bers: ABB, Inc. Memphis, TN Adalet, a division of Scott Fetzer Cleveland, OH AFC Cable Systems, a part of Atkore International New Bedford, MA Arlington Industries, Inc. Scranton, PA Bridgeport Fittings, Inc. Bridgeport, CT Calpipe Industries, Inc. Downey, CA Eaton Highland, IL Emerson Electric Comp
25、any Rosemont, IL ERICO Solon, OH Hubbell Incorporated Shelton, CT IPEX USA LLC Mississauga, ON Canada Killark Electric Manufacturing Company St. Louis, MO Legrand, North America Syracuse, NY Producto Electric Corporation Orangeburg, NY Progressive Machine Die, Inc. Walton Hills, OH Sigma Electric Ma
26、nufacturing Corporation Garner, NC Steel Electric Products Company, Inc. Brooklyn, NY FB 2.10-2013 Page v 2013 National Electrical Manufacturers Association Introduction It is a common perception that in any continuous system, the joints (splices, taps, couplings, connections) are the weakest link.
27、In fact, specifically by design, this is not usually the case. In order to achieve this design performance, variables such as selection; preparation; and assembly technique must be considered. We know it is not practical to have a system without joints, so we strive to build in safety where these oc
28、cur. The expectations and demands on our electrical raceway systems have continued to evolve. Many metallic conduit raceway systems (conduit, fittings, and enclosures) are relied upon both to provide mechanical protection for circuit conductors and to carry potentially dangerous fault currents. Flex
29、ible metallic and nonmetallic conduit and metallic and composite cable systems have been introduced to meet ever-changing market needs. Emerging manufacturing technology and economic pressures have resulted in noticeable changes to some system components. Because of this evolution, sole reliance on
30、the historical mechanical evaluation criteria of the systems components is of increasing concern to those charged with approving an installation. These concerns are very often evidenced through product standards development and installation code processes. Along with evolving manufacturing technolog
31、y, improved and new materials and processes are used in the manufacture of conduit fittings. Considering the variety of materials: steel; iron; aluminum; zinc; and engineered plastics, the industry has come a long way in providing numerous options to solve an infinite number of applications. Through
32、 the years, NEMA member companies who manufacturer conduit fittings have met the needs of the market with new and innovative product designs that continue to live up to higher standards demanded by the market. These guidelines are written by the NEMA Conduit Fittings Section (5-FB) to provide instal
33、lers and inspectors with an industry perspective of best practices in selecting and installing the products we manufacture. Focus is placed on important fundamentals and recent changes to codes, product standards and latest technologies. The member companies of the NEMA Conduit Fittings Section prom
34、ote the selection and installation of listed conduit and cable fittings, listed conduit and cable, and associated supports. Listing of electrical system components qualifies them to minimum performance requirements and provides for ongoing conformity surveillance. Listed conduit fittings can be reco
35、gnized by the trademark of the qualified electrical testing laboratory on the part or its smallest unit container. It is our objective to maintain a closer liaison with the installers of our products and the professional electrical inspector. Through this liaison, we intend to provide uniform educat
36、ion and understanding as to the intended use and application of our products and develop an alliance, founded in trust, that will enable us together to address and resolve the concerns and challenges we each face. Thousands of downloads of earlier editions of this document and its regular use as a r
37、eference in codes and standards forums gives us confidence that we are meeting this objective. This and other valuable NEMA documents are available for downloading free of charge at www.nema.org. NOTEAll references to the National Electrical Code are to the 2011 Edition. FB 2.10- 2013 Page vi 2013 N
38、ational Electrical Manufacturers Association Product Standards and Installation Codes Conduit and cable fittings for use in ordinary (unclassified) locations in the U.S. are typically designed and manufactured to meet the requirements of NEMA Standards Publication ANSI/NEMA FB 1, Fittings, Cast Meta
39、l Boxes, and Conduit Bodies for Conduit and Cable Assemblies. Listed fittings are typically evaluated to Underwriters Laboratories Standard ANSI/UL 514B, Conduit, Tubing and Cable Fittings. Specific use information related to listed fittings is available in the UL General Information for Electrical
40、Equipment Directory, or online at . Conduit and cable fittings designed and manufactured to ANSI/NEMA FB 1 have fundamental design elements in common. NEMA conduit and cable fittings manufacturers have agreed that these basic design and construction features are fundamental to safety, performance, i
41、nterchangeability, and system compatibility. Besides outlining the essential functional characteristics of conduit and cable fittings, NEMA FB 1, as a voluntary consensus design standard, tends to be very specific in suggesting types of materials, acceptable wall thickness, corrosion protection, and
42、 other minimum criteria for metallic components, and physical properties requirements for nonmetallic components. An evaluation by a qualified electrical testing laboratory verifies that listed fittings contain essential design characteristics such as conduit end stops, conduit centering stops (for
43、couplings), smooth-rounded wire entries, minimum corrosion protective coatings, and essential dimensions (e.g. throat diameters) that are within specified tolerances. A listed conduit fitting can be identified by the distinctive trademark of the testing laboratory on the fitting itself and/or on the
44、 smallest unit container. Performance tests include mechanical sequences (e.g. Assembly, Bend Tests, Pull Tests) and electrical tests (e.g. electrical resistance before and after Bend Test in mechanical sequence, Fault Current Test, Electrical Continuity Test) designed to represent “real life” for t
45、hese fittings both during installation and in service throughout the useful life of the system. As one might imagine, these standards are dynamic and change over time to facilitate the introduction of new technologies and to address the needs and expectations of the installer and the electrical insp
46、ector. They also meet with the intent of NEC Section 110.3(B) by providing the installer with necessary information. Given that all “listed” fittings have met the appropriate design and performance requirements, selection of the right fitting for the application is the single most important factor l
47、eading to a safe, effective, and permanent installation. The way things used to be, “Ive always used that fitting for this application,” may not be the right way today. We have to get back to the fundamentals. Beyond selection of the right fitting for the application, almost every other variable com
48、es down to good workmanship, something every craftsman takes pride in and that is fundamentally required by NEC Section 110.12, and personal preference in selecting optional features and benefits that distinguish alternative brands. FB 2.10-2013 Page vii 2013 National Electrical Manufacturers Associ
49、ation FB 2.10-2013 Page 1 2013 National Electrical Manufacturers Association Section 1 FITTINGS FOR USE WITH ELECTRICAL METALLIC TUBING (EMT) Steel or aluminum Electrical Metallic Tubing (EMT) is for use in virtually all types of electrical systems as a raceway for branch circuits, feeders, and service entrances. EMT is permitted in both wet and dry locations and may be buried directly in earth or embedded in concrete. For a detailed description of the permitted uses of EMT, refer to NFPA 70, N
