1、 ANSI C12.8-1981 (R1997, R2002, R2012) American National Standard Test Blocks and Cabinets for Installation of Self-Contained “A” Base Watthour Meters ANSI C12.8-1981 (R1997, R2002, R2012) American National Standard Test Blocks and Cabinets for Installation of Self- Contained “A” Base Watthour Meter
2、s Secretariat: National Electrical Manufacturers Association Approved: May 19, 2011 Published: December 18, 2012 American National Standards Institute, Inc. C12.8-1981 (R1997, 2002, R2012) Page ii Copyright 2012 by National Electrical Manufacturers Association NOTICE AND DISCLAIMER The information i
3、n 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 this docu
4、ment. 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 persons
5、 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 any inf
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12、all not be attributable to NEMA and is solely the responsibility of the certifier or maker of the statement. C12.8-1981 (R1997, 2002, R2012) Page iii Copyright 2012 by National Electrical Manufacturers Association American National Standard Approval of an American National Standard requires verifica
13、tion by ANSI that the requirements for due process, consensus, and other criteria for approval have been met by the standards developer. Consensus is established when, in the judgment of the ANSI Board of Standards Review, substantial agreement has been reached by directly and materially affected in
14、terests. Substantial agreement means much more than a simple majority, but not necessarily unanimity. Consensus requires that all views and objections be considered, and that a concerted effort be made toward their resolution. The use of American National Standards is completely voluntary; their exi
15、stence does not in any respect preclude anyone, whether he has approved the standards or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not conforming to the standards. The American National Standards Institute does not develop standards and will in no ci
16、rcumstances give an interpretation of any American National Standard. Moreover, no person shall have the right or authority to issue an interpretation of an American National Standard in the name of the American National Standards Institute. Requests for interpretations should be addressed to the se
17、cretariat or sponsor whose name appears on the title page of this standard. CAUTION NOTICE: This American National Standard may be revised or withdrawn at any time. The procedures of the American National Standards Institute require that action be taken periodically to reaffirm, revise, or withdraw
18、this standard. Purchasers of American National Standards may receive current information on all standards by calling or writing the American National Standards Institute. Published by National Electrical Manufacturers Association 1300 N. 17th Street, Rosslyn, Virginia 22209 Copyright 2012 by the Nat
19、ional 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 Conventions. No part of this
20、publication may be reproduced in any form, in an electronic retrieval system or otherwise, without prior written permission of the publisher. Printed in the United States of America. C12.8-1981 (R1997, R2002, R2012) Page iv Copyright 2012 by National Electrical Manufacturers Association TABLE OF CON
21、TENTS Page FOREWORD.v SECTION 1 SCOPE1 SECTION 2 DEFINITIONS.1 2.1 Cabinet, Test Block.1 2.2 Connector1 2.3 Disconnect.1 2.4 Test Block1 SECTION 3 STANDARD RATINGS.1 3.1 Current1 3.2 Voltage.1 SECTION 4 GENERAL REQUIREMENTS.1 4.1 Spacings.1 4.2 Temperature Rise.1 4.3 Assembly Bolts2 4.4 Connectors.2
22、 4.5 Connector Nuts2 4.6 Test Clips2 4.7 Barriers.2 4.8 Disconnect Device2 4.9 Material of Base.2 4.10 Mounting Holes3 SECTION 5 TEST-BLOCK DIMENSIONS AND CONFIGURATIONS.3 5.1 Dimensions.3 5.2 Test-Block Figures.3 SECTION 6 TEST-BLOCK-CABINETS9 6.1 Dimensions for Indoor Test-Block Cabinets9 6.2 Cabi
23、net Cover9 6.3 Cabinet Material.9 6.4 Cabinet Construction9 C12.8-1981 (R1997, R2002, R2012) Page v Copyright 2012 by National Electrical Manufacturers Association ANSI C12.8-1981 (R-1997) FOREWORD (This foreword is not part of ANSI C12.8-1981 (R1997) American National Standard for Test Blocks and C
24、abinets for the Installation of Self-Contained A-Base Watthour Meters.) This standard covers the dimensions and functions of test blocks and cabinets used with self-contained A-base Watthour meters. This standard supersedes the requirements of the former AEIC-EEI-NEMA Standard for Test Blocks and Ca
25、binets for the Installation of Self-contained “A“ Base Watthour Meters, MSJ-8-1951, NEMA 103-1951. Suggestions for improvement to this standard are welcome. They should be sent to the Senior Technical Director, Operations National Electrical Manufacturers Association 1300 North 17thStreet Rosslyn, V
26、A 22209 This standard was processed and approved for submittal to ANSI by American National Standards Committee on Electricity Metering, C12. Committee approval of the standard does not necessarily imply that all committee members voted for its approval. At the time it approved this standard, the C1
27、2 Committee had the following members: Tom Nelson, Chair Paul Orr, Secretary Organization Represented Name of Representative Electric Light and Power Group (The Association of Edison Illuminating Companies and the Edison Electric Institute) J. McEvoy T. Vahlstrom J. MiningL. PananenInstitute of Elec
28、trical and Electronics Engineers . H. Millican National Institute of Standards and Technology . N. Oldham National Electrical Manufacturers Association . W . Germer T. C. DrewF. A. Marta Underwriters Laboratories . R. Breschini Rural Electrification Administration . S. Jones Florida Public Service C
29、ommission J. Ruehl C12.8-1981 (R1997, 2002, R2012) Page vi Copyright 2012 by National Electrical Manufacturers Association City of Los Angeles . C. Gomez C12.8-1981 (R1997, R2002, R2012) Page 1 Copyright 2012 by National Electrical Manufacturers Association AMERICAN NATIONAL STANDARD ANSI C12.8-1981
30、 (R1997, R2002, R2012) American National Standard for Test Blocks and Cabinets for Installation of Self-Contained A-Base Watthour Meters 1 SCOPE This standard covers the dimensions and functions of test blocks and cabinets used with self-contained A-base Watthour meters. 2 DEFINITIONS 2.1 CABINET, T
31、EST BLOCK An enclosure to house a test block and wiring for a bottom-connected Watthour meter. 2.2 CONNECTOR A coupling device employed to connect conductors of one circuit or transmission element with those of another circuit or transmission element. 2.3 DISCONNECT A conductor, bar, or nut used to
32、open an electrical circuit for isolation purposes. 2.4 TEST BLOCK A terminal block with provisions for bypassing an electrical load to isolate a meter or other device for test purposes. 3 STANDARD RATINGS 3.1 CURRENT Ratings shall be 100 A and 200 A. 3.2 VOLTAGE Ratings shall be 300 V and 600 V. 4 G
33、ENERAL REQUIREMENTS 4.1 SPACINGS Spacings shall be as indicated in Table 1. Grounded metal includes the enclosure and any metal in permanent electrical connection with the enclosure. 4.2 TEMPERATURE RISE The temperature rise of current-carrying parts shall not exceed 55C above an ambient temperature
34、 of 25C at 100% of rated current. C12.8-1981 (R1997, 2002, R2012) Page 2 Copyright 2012 by National Electrical Manufacturers Association 4.3 ASSEMBLY BOLTS Assembly bolts shall be of brass, cadmium-plated steel, or the equivalent and shall have a thread No 12-24. Note: The cadmium coating shall be n
35、ot less than 0.0005 inch thick in order to conform with type NS, as described in ANSI/ASTM A165-80, Specification for Electrodeposited Coatings of Cadmium on Steel. 4.4 CONNECTORS Connectors shall be the solderless type and accommodate the following wire sizes: Device Rating (A) AWG Wire Size 100 20
36、0 No 8 to No 1/0 No 1/0 to 250 kcmil 4.5 CONNECTOR NUTS Connector nuts shall be of brass, cadmium-plated steel, or other materials suitable for the purpose, and shall have a 0.500 inch short diameter across flats (see note in 4.3). 4.6 TEST CLIPS Means for safely attaching test clips shall be provid
37、ed on both sides of the disconnecting device. Means may consist of one (1) grooved connector nuts suitable for attaching 40 A Mueller copper test clips or two (2) extra nuts for attaching lugs of jumpers. Table 1 - Minimum Spacings Minimum Spacings from Live Parts to Voltage Parts of Opposite Polari
38、tyaGrounded Metalb Between Parts Over Through Over Through Involved (V) Surface (in) Air (in) Surface (in) Air (in) 0-300c 0.750 0.375 0.500 0.375 301-600 1.250 0.750 1.000 0.500 a. Through-air and over-surface spacings of 0.375 inch, to be acceptable at other than wiring terminals, to cast-metal en
39、closure or to grounded metal where indentation or deformation of the overall enclosure will not affect spacings, shall withstand a dielectric strength test at 6000 V, 60 Hz, for 1 min. b. Through-air and over-surface spacings of 0.3475 inch between parts of opposite polarity, to be acceptable at oth
40、er than wiring terminals, shall withstand a dielectric strength test at 6000 V, 60 Hz, for 1 min. c. 300 V spacings shall apply in a 600 V test block if the phase-to-neutral potential does not exceed 300 V for spacings (1) from neutral to phase-potential parts and (2) from neutral to grounded metal.
41、 4.7 BARRIERS Barriers may be an integral part of the base or a separate part fastened to the base. 4.8 DISCONNECT DEVICE The disconnect device may consist of links, raising nuts, or some other device of a satisfactory design. 4.9 MATERIAL OF BASE The material of the base shall be suitable for the s
42、ole support of uninsulated current-carrying parts. C12.8-1981 (R1997, R2002, R2012) Page 3 Copyright 2012 by National Electrical Manufacturers Association 4.10 MOUNTING HOLES Mounting holes shall be centered between the top and bottom of the test block. Clearance shall be provided for mounting screw
43、s No 10-32. 5 TEST-BLOCK DIMENSIONS AND CONFIGURATIONS 5.1 DIMENSIONS All drawings are dimensioned in inches. To convert to the metric system in millimeters, multiply the dimensions in inches by 25.4. The resulting metric dimensions shall be rounded to the nearest 0.02 mm. 5.2 TEST-BLOCK FIGURES Cur
44、rent Rating (A) Connection Sequence Figure 100 Line-Load 1 100 Line-Line-Line-Load-Load-Load 2 200 Line-Load 3 200 Line-Load, alternate construction 4 Neutral block 5 C12.8-1981 (R1997, 2002, R2012) Page 4 Copyright 2012 by National Electrical Manufacturers Association C12.8-1981 (R1997, R2002, R201
45、2) Page 5 Copyright 2012 by National Electrical Manufacturers Association C12.8-1981 (R1997, 2002, R2012) Page 6 Copyright 2012 by National Electrical Manufacturers Association C12.8-1981 (R1997, R2002, R2012) Page 7 Copyright 2012 by National Electrical Manufacturers Association C12.8-1981 (R1997,
46、2002, R2012) Page 8 Copyright 2012 by National Electrical Manufacturers Association C12.8-1981 (R1997, R2002, R2012) Page 9 Copyright 2012 by National Electrical Manufacturers Association 6 TEST-BLOCK CABINETS 6.1 Dimensions for indoor test-block cabinets Size (inches) Height Width Depth Figures 14.
47、0 13.5 4.5 6 10.5 12.5 4.5 7 6.2 Cabinet cover The cabinet cover shall be equipped so that it can be sealed and shall be hinged on the left side. 6.3 Cabinet material The test-block cabinet shall be formed of 0.056 inch steel or 0.075 inch aluminum. 6.4 Cabinet construction Cabinet construction shal
48、l be NEMA Type 1, in accordance with NEMA 250-1980, Enclosures for Electrical Equipment (1000 V Maximum). C12.8-1981 (R1997, 2002, R2012) Page 10 Copyright 2012 by National Electrical Manufacturers Association C12.8-1981 (R1997, R2002, R2012) Page 11 Copyright 2012 by National Electrical Manufacturers Association
