1、NEMA Standards PublicationNational Electrical Manufacturers AssociationNEMA GR 1-2017Ground Rod Electrodes and Ground Rod Electrode CouplingsNEMA Standards Publication GR 1-2017 Ground Rod Electrodes and Ground Rod Electrode Couplings Published by National Electrical Manufacturers Association 1300 N
2、orth 17thStreet, Suite 900 Rosslyn, Virginia 22209 www.nema.org 2017 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 t
3、he International and Pan American copyright conventions. 2017 National Electrical Manufacturers Association NOTICE AND DISCLAIMER During the development of this standard, the persons engaged in reaching consensus could not achieve consensus about what to name specific nominal trade size designations
4、 for zinc-coated ground rods in Tables 3.1, 3.2 and 6.1. A review during an appeal determined that the inability to achieve consensus was attributable to a commercial and competitive disagreement among manufacturers. The appeals decision directed that trade size designations for zinc-coated, copper-
5、bonded, and stainless-steel ground rods be treated with consistency within the standard. When consensus could not be achieved again following the appeal, the Executive Committee of the NEMA Board of Governors resolved the disagreement by approving the nominal trade size designations shown in the “tr
6、ade size” column in each of these three tables, and further directed, at the recommendation of NEMAs Codes & Standards Committee, that the foreword of this standard bring to the readers attention the history of these changes to minimize potential confusion. Accordingly, Table 3.1 identifies zinc-coa
7、ted ground rods of different dimensions by their finished mean diameter and the minimum and maximum diameters for a given “trade size” of zinc-coated ground rod. Table 3.2 contains corresponding dimensions for the end point configurations for each trade size, and Table 6.1 recites application diamet
8、ers for threadless couplings for each trade size of zinc-coated ground rod. In addition to the information in the foreword and the standard, the user is encouraged to consult with the manufacturer about couplings and connectors to be used with specific grounding rods. In all other respects, the info
9、rmation 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
10、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 standards development process. This process brings together volunteers and/or seeks out the views o
11、f 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 o
12、f 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 resultin
13、g 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 fulf
14、ill 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 o
15、ther 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 determini
16、ng 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
17、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 certification or other statement of compliance with any health or safetyrelated information in this doc
18、ument shall not be attributable to NEMA and is solely the responsibility of the certifier or maker of the statement. NEMA GR 1-2017 Page i 2017 National Electrical Manufacturers Association CONTENTS Foreword . v Section 1 General . 1 1.1 Scope . 1 1.2 Normative References . 1 1.3 Units Of Measuremen
19、t . 2 1.4 Definitions 2 Section 2 Copper-Bonded Ground Rod Electrodes 3 2.1 Steel Core Properties 3 2.2 Copper Thickness 3 2.3 Length 3 2.4 Ground Rod Electrode Diameters . 3 2.5 Threads 4 2.6 End Configurations 4 2.7 Adhesion 5 2.7.1 Test Method . 5 2.7.2 Evaluation of Adhesion 5 2.8 Ductility 6 2.
20、8.1 Test Method . 6 2.8.2 Evaluation of Ductility 6 2.9 Finish . 6 2.10 Straightness . 6 2.10.1 Test Method . 6 2.10.2 Evaluation of Straightness . 6 2.11 Markings 7 Section 3 Zinc-Coated Ground Rod Electrodes 8 3.1 Steel Core Properties 8 3.2 Zinc Coating. 8 NEMA GR 1-2017 Page ii 2017 National Ele
21、ctrical Manufacturers Association 3.2.1 Coating Method . 8 3.2.2 Thickness. 8 3.2.3 Measurement . 8 3.3 Length 8 3.4 Ground Rod Electrode Diameters . 9 3.5 Adhesion 9 3.5.1 Test Method . 9 3.5.2 Evaluation of Adhesion 10 3.6 Finish . 10 3.7 Straightness . 10 3.7.1 Test Method . 10 3.7.2 Evaluation o
22、f Straightness . 10 3.8 End Configurations 10 3.9 Markings 12 Section 4 Stainless Steel Ground Rod Electrodes 13 4.1 Steel Properties . 13 4.2 Length 13 4.3 Ground Rod Electrode Diameters . 13 4.4 Finish . 13 4.5 Straightness . 14 4.5.1 Test Method . 14 4.5.2 Evaluation 14 4.6 End Configurations 14
23、4.7 Markings 15 4.8 Threads 15 Section 5 Couplings for Copper-Bonded Ground Rod Electrodes . 16 5.1 Physical Properties 16 5.1.1 Surface Condition 16 5.1.2 Material 16 NEMA GR 1-2017 Page iii 2017 National Electrical Manufacturers Association 5.2 Construction. 16 5.2.1 Length 16 5.2.2 Application Di
24、ameter . 16 5.3 Performance 17 5.3.1 Conductivity . 17 5.3.2 Impact 17 5.3.3 Pullout 18 5.3.4 Bend 18 5.3.5 Mechanical Strength 18 5.4 Markings 18 Section 6 Couplings for Zinc-Coated Ground Rod Electrodes 19 6.1 Physical Properties 19 6.1.1 Surface Condition 19 6.1.2 Material 19 6.2 Construction. 19
25、 6.2.1 Length 19 6.2.2 Threadless Ground Rod Electrode Couplings . 19 6.3 Performance 20 6.3.1 Conductivity . 20 6.3.2 Impact 20 6.3.3 Pullout 21 6.3.4 Bend 21 6.3.5 Mechanical Strength 21 6.4 Markings 21 Section 7 Couplings for Stainless Steel Ground Rod Electrodes . 22 7.1 Physical Properties 22 7
26、.1.1 Surface Condition 22 7.1.2 Material 22 7.2 Construction. 22 NEMA GR 1-2017 Page iv 2017 National Electrical Manufacturers Association 7.2.1 Length 22 7.2.2 Application Diameter . 22 7.3 Performance 23 7.3.1 Conductivity . 23 7.3.2 Impact 23 7.3.3 Pullout 24 7.3.4 Bend 24 7.3.5 Mechanical Streng
27、th 24 7.4 Markings 24 TABLES 2-1 Finished Diameter Ranges for Copper-Bonded Ground Rod Electrodes . 3 2-2 Thread Specifications 4 3-1 Finished Diameter Ranges for Zinc-Coated Ground Rod Electrodes . 9 4-3 Thread Specifications 15 5-1 Coupling Thread Sizes For Threaded Copper-Bonded Ground Rod Electr
28、odes 16 6-1 Application Diameters for Threadless Couplings for Threadless Zinc-Coated Ground Rod Electrodes 20 7-1 Coupling Thread Sizes for Threaded Stainless Steel Ground Rod Electrodes 22 FIGURES 2-1 Thread Specification 4 2-2 End Configuration 5 2-3 Apparatus for Straightness Test . 7 3-1 End Co
29、nfiguration 10 3-2 Alternative End Configurations 12 4-1 End Configuration 14 NEMA GR 1-2017 Page v 2017 National Electrical Manufacturers Association Foreword This standards publication provides practical information concerning construction, test, performance, and manufacture of ground rod electrod
30、es and ground rod electrode couplings. This standard 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 manufacture and widespread product availability. One of the primary purpose
31、s of this standards publication is to encourage the manufacture and utilization of products, which, in themselves, function in accordance with these standards. While some sections of this publication are intended to eliminate misunderstandings between manufacturers and users, all sections, when appl
32、ied properly, contribute to safety in one way or another. The proper manufacture of ground rod electrodes and ground rod electrode couplings is, however, only one consideration in promoting the safe utilization of electricity. Other safety considerations, including environmental conditions, system d
33、esign, equipment selection and application, installation, operating practices, and maintenance, involve the joint efforts of the system designer, the various equipment manufacturers, the installer, and the user. Information is provided herein to assist in proper selection and use. Trade Sizes. Trade
34、 sizes for copper-bonded, zinc-coated, and stainless steel ground rods and couplings have been a prominent feature of this standard since 1997. Trade size designations are often nominal in character and do not always reflect actual size dimensions.1Trade sizes for lumber are perhaps the most well-kn
35、own example. That has been true over the history of this standard as well. Historically, the diameters of ground rods for copper-bonded, zinc-coated, and stainless steel ground rods have been smaller than their corresponding nominal trade size designations in the standard. Trade size can serve an im
36、portant function for manufacturers, customers, and users by providing a convenient means of identifying products and complementary products with certain attributes. In the case of ground rods and this standard, trade size facilitates the identification of ground rods with a certain diameter, the end
37、 point configuration of the ground rod, and the identification of couplings that fit with the ground rod sharing a corresponding trade size designation. There are safety and product compatibility interests in facilitating the identification of ground rods and appropriately sized couplings that are i
38、ntended to work together. Since this standard was first developed in 1997, the tables relating to zinc-coated ground rods changed during each revision, while the tables relating to copper-bonded and stainless steel ground rods have remained relatively unchanged. The changes in the 2005/2007 versions
39、 of the standard, in addition to introducing metric measurements for the first time, deleted specific references to certain zinc-coated ground rods and couplings that were commercially available but had slightly smaller dimensions. This version of the standard restores references to those other comm
40、ercially available zinc-coated ground rods as well as the corresponding couplings and restores the nominal trade size designations in a manner consistent with the nominal trade size designations for copper-bonded and stainless steel ground rods. The tables below reflect the historical evolution of t
41、he trade size designations for zinc-coated ground rods in this standard since 1997. As the reader can see, this standard has historically recognized that trade size designations do not exactly match the actual diameter dimension of the ground rod. The tables for copper-bonded ground rods and stainle
42、ss steel ground rods demonstrate that the same is true for those ground rods as well. What is new for this version of the standard is that Table 3.1 for zinc-coated ground rods recognizes commercially available zinc-coated ground rod electrodes reflecting a greater variety of 1For example, The Natio
43、nal Electric Code at Article 90.9 (units of measurement)(2014 ed.) notes that trade size and actual sizes can deviate: Where the actual measured size of a product is not the same as the nominal size, trade size designators shall be used rather than dimensions. Trade practices shall be followed in al
44、l cases. NEMA GR 1-2017 Page vi 2017 National Electrical Manufacturers Association diameters compared to the 2005/2007 version of the standard. This version of the standard also introduces a new measurement for all ground rods: finished rod mean diameter. These additional zinc-coated ground rods and
45、 their dimensions (minimum and maximum diameters, end point configuration) and the new finished mean diameter measurement reflect the consensus of NEMA members who developed this version of the standard for each category in Table 3.1. For the benefit of the reader, here are the historical trade size
46、 designations since 1997 found in this standard: NEMA GR1-1997, Table 3.1Zinc-Coated Ground Rod Electrodes TRADE SIZE Diameter Range Inches Minimum Maximum 1/2 0.50 0.514 5/8 0.60 0.614 3/4 0.725 0.739 1 0.975 0.989 NEMA GR1-2001, Table 3.1Zinc-Coated Ground Rod Electrodes TRADE SIZE Diameter Range
47、Inches Minimum Maximum 1/2 0.484 0.50 5/8 0.539 0.555 3/4 0.657 0.675 NEMA GR1-2005, Table 3.1Zinc-Coated Ground Rod Electrodes TRADE SIZE Diameter Range Inches and Millimeters Minimum Maximum mm in. mm in. 5/8 15.88 0.625 16.26 0.640 3/4 19.06 0.750 19.43 0.765 1 25.40 1 25.78 1.015 NEMA GR 1-2017
48、Page vii 2017 National Electrical Manufacturers Association NEMA GR1-2017, Table 3.1Zinc-Coated Ground Rod Electrodes TRADE SIZE Finished Rod Mean Diameter (inches) Diameter Range Inches and Millimeters Minimum Maximum mm in. mm in. 5/8 0.547 13.690 0.539 14.10 0.555 5/8F 0.633 15.880 0.625 16.26 0.
49、640 3/4T 0.666 16.690 0.657 17.15 0.675 3/4 0.735 18.260 0.719 19.05 0.750 3/4F 0.758 19.05 0.750 19.43 0.765 1 1.008 25.40 1 25.78 1.015 The evolution of the 2017 nominal trade size designations for zinc-coated ground rod electrodes from NEMA GR1-2001 to NEMA GR1-2005 to NEMA GR1-2017 can be seen in the table immediately below: 2017 (now) 2005 (previously) 2001 (previously) 5/8 Not included 5/8 5/8F 5/8 Not included 3/4T Not included 3/4 3/4 Not included Not included 3/4F 3/4 Not included 1 1 Not included What is new to Table 3.1 in the 2017 version of the standard
