1、NEMA Standards PublicationNational Electrical Manufacturers AssociationANSI/NEMA FB 1-2014Fittings, Cast Metal Boxes, and Conduit Bodies for Conduit, Electrical Metallic Tubing, and CableApproved as an American National Standard ANSI Approval Date: October 29, 2014 NEMA Standards Publication FB 1-20
2、14 Fittings, Cast Metal Boxes, and Conduit Bodies for Conduit, Electrical Metallic Tubing, and Cable Published by National Electrical Manufacturers Association 1300 North 17th Street, Suite 900 Rosslyn, VA 22209 www.nema.org 2014 National Electrical Manufacturers Association. All rights, including t
3、ranslation 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 conventions. 2014 National Electrical Manufacturers Association NOTICE AND DISCLAIMER The infor
4、mation 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 mean that there is unanimous agreement among every person participating in the development of t
5、his 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 standards development process. This process brings together volunteers and/or seeks out the views of
6、 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 document and it does not independently test, evaluate, or verify the accuracy or completeness of
7、 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 whatsoever, whether special, indirect, consequential, or compensatory, directly or indirectly resulting
8、 from the publication, use of, application, or reliance on this document. NEMA disclaims and makes no guaranty or warranty, express or implied, as to the accuracy or completeness of any information published herein, and disclaims and makes no warranty that the information in this document will fulfi
9、ll 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 publishing and making this document available, NEMA is not undertaking to render professional or ot
10、her 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 independent judgment or, as appropriate, seek the advice of a competent professional in determinin
11、g 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 consult for additional views or information not covered by this publication. NEMA has no power, nor d
12、oes 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 certification or other statement of compliance with any health- or safety-related information in this do
13、cument shall not be attributable to NEMA and is solely the responsibility of the certifier or maker of the statement. ANSI/NEMA FB 1-2014 Page i 2014 National Electrical Manufacturers Association Foreword This Standards Publication provides practical information concerning construction, test, perfor
14、mance, and manufacture of fittings, cast metal boxes, and conduit bodies for conduit, tubing, and cable assemblies. It is intended for use by the electrical industry to provide guidelines for the manufacture and proper application of these products, and to promote the benefits of repetitive manufact
15、ure and widespread product availability. One of the primary purposes of this Standards Publication is to encourage the manufacture and utilization of products that function in accordance with this standard. While some sections of this publication are intended to eliminate misunderstandings between m
16、anufacturers and users, all sections, when applied properly, contribute to safety in one way or another. The proper manufacture of fittings, cast metal boxes, and conduit bodies is, however, only one consideration in promoting the safe use of electricity. Other safety considerations involve the join
17、t efforts of the system designer, the various equipment manufacturers, the installer, and the user. Information is provided in this standard, and in NEMA Standards Publications FB 2.10 and FB 2.20, to assist in proper selection and use. The following factors are vital in a safe electrical system and
18、 should be considered by the user in the selection and application of equipment covered by the publication: a) Environmental conditions b) System design c) Equipment selection and application d) Installation e) Operating practices f) Maintenance This Standards Publication has been published with a v
19、iew to promoting the safety of persons and property when products conforming to it are selected, installed, and maintained in accordance with the National Electrical Code (NEC). NEMA Standards Publications are periodically reviewed to meet changing conditions and technical progress, and the latest e
20、dition shall be utilized. Comments from the users of this Standards Publication are welcome and should be sent to: Senior Technical Director, Operations National Electrical Manufacturers Association 1300 North 17th Street, Suite 900 Rosslyn, VA 22209 ANSI/NEMA FB 1-2014 Page ii 2014 National Electri
21、cal Manufacturers Association At the time of publication, the Conduit Fittings Section of NEMA had the following members: Adalet, a Division of Scott Fetzer Cleveland, OH AFC Cable Systems, Part of Atkore International New Bedford, MA Appleton Group Rosemont, IL Arlington Industries, Inc. Scranton,
22、PA Bridgeport Fittings, Inc. Bridgeport, CT Calpipe Industries, Inc. Rancho Dominguez, CA Crouse-Hinds by Eaton Syracuse, NY Eatons B-Line Business Highland, IL ERICO Solon, OH Hubbell Incorporated Shelton, CT IPEX Management Inc. Mississauga, ON, Canada Legrand/Pass 14 Threads per Inch (Based on Ma
23、le NPT Thread Gauging of L1 + 0 Flush) . 37 Figure 10 NPT Male to NPT Female Thread Engagement Trade Sizes 1, 1, 1, and 2; 11 Threads per Inch (Based on Male NPT Thread Gauging of L1 + 0 Flush) 37 Figure 11 NPT Male to NPT Female Thread Engagement Trade Sizes 2, 3, 3, 4, 5, and 6; 8 Threads per Inch
24、 (Based on Male NPT Thread Gauging of L1 + 0 Flush) . 38 Tables Table 1 Trade Size and Metric Designators . 5 Table 2 Standard Assembly Torque Values for Conduit and Cable Fittings . 11 Table 3 Inside Diameter of Throats and End Stops for Fittings and Bushings 11 Table 4 Thickness of Zinc Corrosion
25、Protective Coating . 12 Table 5 Wall Thickness of Fittings . 12 Table 6 Metal Thickness . 12 Table 7 Minimum Thread Projection of Box Connectors 13 Table 8 Minimum Wall Thickness at Tapped Holes for Conduit 13 Table 9 Diameter of Plug Go-gauge 22 Table 10 Radius of Bend of Angle Fittings 22 Table 11
26、 Outside Diameter of Flexible Metal Conduit Fitting of the Screw-inType . 22 Table 12 Armored Cable Bushing Dimensions . 23 Table 13 Distance from Removable Cover to Opposite Wall with Raceway Opening 23 Table 14 Number of Turns Past L1 Gauging Notch of Working NPT Plug Gauge for NTC Threaded Condui
27、t Entries 33 Table 15 Number of Turns Past L1 Gauging Notch of Working NPT Plug Gauge for NTCM Threaded Conduit Entries 33 Table 16 Minimum Depth to Integral Bushings 34 Table 17 Gauging Requirements for External Tapered Threads for Conduit Fittings for Use with Threaded Rigid Metal Conduit Coupling
28、s, Threaded Intermediate Metal Conduit Couplings, or Other Electrical Fittings Having Tapered or Straight Internal Threads (Cut Threadsfor Ordinary Location Applications Only) 35 Table 18 Maximum Number of Threads in the Wall of a Cast Metal Box Having Through-threaded Entries . 35 Table 19 Compatib
29、ility of Knockout Dimensions with Locknuts, Bushings, and Metal Conduit (IMC or Rigid) to Assure Coordination* 39 ANSI/NEMA FB 1-2014 Page vi 2014 National Electrical Manufacturers Association ANSI/NEMA FB 1-2014 Page 1 2014 National Electrical Manufacturers Association Section 1 GENERAL 1.1 SCOPE T
30、his Standards Publication covers fittings that are a part of electrical raceway systems designed for use as intended by the requirements of the National Electrical Code (NEC), NFPA 70. Specifically, this standard covers fittings for use with non-flexible tubular raceways: Rigid and Intermediate Meta
31、l Conduit and Electrical Metallic Tubing. Also included are fittings for use with flexible conduit and cable raceways, including: Flexible Metal Conduit and liquidtight flexible conduits, Armored Cable, Metal Clad Cable, Tray Cable, Mineral Insulated Cable, Flexible Cord, Nonmetallic Sheathed Cable,
32、 and Service Entrance Cable. The Family Tree of the Conduit Fittings Industry is provided for reference in Appendix A. This standard also includes cast metal outlet boxes and covers, as well as conduit bodies and covers, which when designed for the purpose, serve as a box intended to house conductor
33、 splices and/or wiring devices; and cast metal junction boxes, pull boxes, and covers. This standard does not include standard conduit couplings of the type provided with lengths of Rigid and Intermediate Metal Conduit, or threaded conduit nipples, or threaded or unthreaded factory-made bends derive
34、d from Rigid and Intermediate Metal Conduit or Electrical Metallic Tubing. This standard does not apply to fittings, boxes, or enclosures that are for use in Class I, Division 1; Class II, Division 1; Class III, Division 1; Class I, Zones 0, 1, 2; Zones 20, 21, or 22 hazardous (classified) locations
35、. Exceptions are those ordinary (unclassified) location fittings and enclosures that are specifically permitted by the NEC in these locations. 1.2 NORMATIVE REFERENCES The following normative documents contain provisions, which through reference in this text, constitute provisions of this Standards
36、Publication. By reference herein these publications are adopted, in whole or in part as indicated, in this Standards Publication. Unless otherwise stated, references are to the latest edition of the standard. American National Standards Institute (ANSI) 25 West 43rd Street, 4th Floor New York, NY 10
37、036 ANSI C80.1 American National Standard for Electrical Rigid Steel Conduit (ERSC) ANSI C80.3 Steel Electrical Metallic Tubing ANSI C80.5 Electrical Rigid Aluminum Conduit ANSI C80.6 Electrical Intermediate Metal Conduit American Society of Mechanical Engineers (ASME) International Three Park Avenu
38、e New York, NY 10016-5990 ANSI/ASME B1.20.1 Pipe Threads, General Purpose, Inch ASTM International (ASTM) 100 Barr Harbor Drive West Conshohocken, PA 19428-2959 ASTM B 86 Specification for Zinc and Zinc-Aluminum Alloy Foundry and Die Castings ANSI/NEMA FB 1-2014 Page 2 2014 National Electrical Manuf
39、acturers Association National Electrical Manufacturers Association (NEMA) 1300 North 17th Street, Suite 900 Rosslyn, VA 22209-3081 NEMA 250 Enclosures for Electrical Equipment (1000 V Maximum) NEMA FB 2.10 Selection and Installation Guidelines for Fittings for Use with Non-Flexible Conduit and Tubin
40、g NEMA FB 2.20 Selection and Installation Guidelines for Fittings for Use with Flexible Conduit, Tubing, and Cable NEMA OS 1 Sheet-Steel Outlet Boxes, Device Boxes, Covers and Box Supports NEMA WD 6 Wiring Devices Dimensional Requirements National Fire Protection Association (NFPA) 1 Batterymarch Pa
41、rk Quincy, MA 02169-7471 NFPA 70 National Electrical Code Institute of Electrical and Electronic Engineers (IEEE) 445 Hoes Lane, P.O. Box 1331 Piscataway, NJ 08855-1331 IEEE 268 Standard for Use of the International System of Units (SI): The Modern Metric System Underwriters Laboratories LLC 333 Pfi
42、ngsten Road Northbrook, IL 60062-2096 UL 6 Standard for Rigid Metal Conduit UL 50E Standard for Electrical Enclosures, Environmental Considerations UL 467 Standard for Grounding and Bonding UL 514A Standard for Metallic Outlet Boxes UL 514B Standard for Fittings for Conduit and Outlet Boxes UL 514C
43、Standard for Nonmetallic Outlet Boxes UL 514D Standard for Flush Device Cover Plates UL 797 Standard for Electrical Metallic Tubing UL 1242 Standard for Intermediate Metallic Conduit NOTESome of these standards may also be standards of the Canadian Standards Association (CSA) and the Association of
44、Standardization and Certification (ANCE). 1.3 UNITS OF MEASUREMENT The primary units of measure in this Standards Publication are based on SI metric units in accordance with the American National Standard for metric practice, ANSI/IEEE Standard 268, Standard for Use of the International System of Un
45、its (SI): The Modern Metric System. SI metric units are followed by their Imperial inch-pound equivalent in parentheses, with the exception of trade sizes of conduit, tubing or cable, thread dimensions, or conductor sizes, in which case the inch-pound unit appears first. In general, the metric conve
46、rsions are “soft,” representing rounded approximation of the inch-pound measure. When two values are shown, the first stated value is the requirement. No SI metric units should be assigned to trade sizes of conduit, tubing or cable, thread dimensions, or conductor sizes. Metric Designators have been
47、 adopted that directly correspond to traditional trade sizes (Example: 16). The use of these Metric Designators in conjunction with, but not replacing, traditional trade ANSI/NEMA FB 1-2014 Page 3 2014 National Electrical Manufacturers Association sizes, is a recommendation for future design. See Ta
48、ble 1 for Metric Designators corresponding to traditional trade sizes. NOTEMetric designators and trade sizes are for identification purposes only and do not relate to actual dimensions. 1.4 DEFINITIONS angle fitting: A fitting, such as an elbow or offset fitting, with or without a removable cover (
49、or cap) intended to change the direction of the raceway. box, FS or FD: A cast metal box having internal or external hubs or pads for drilling or tapping for attachment to conduit or cable assemblies. The box is designed to accommodate single-strap wiring devices and can be used as a pull or junction box. The box is designed for surface mounting in single or multiple gang. box, junction: A box with a cover. It joins different runs of raceways or cables, or both, and provides space for the connection and branching of the enclose
