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BOOK™ green IEEE 142™ IEEE Recommended Practice for Grounding of Industrial and Commercial Power Systems Published by the Institute of Electrical and Electronics Engineers, Inc. IEEE Std 142™-2007 (Revision of IEEE Std 142-1991) IEEE Std 142™-2007 (Revision of IEEE Std 142-1991) IEEE Recommended Practice for Grounding of Industrial and Commercial Power Systems Sponsor Power Systems Engineering Committee of the IEEE Industry Applications Society Approved 7 June 2007 IEEE-SA Standards Board Abstract: The problems of system grounding, that is, connection to ground of neutral, of the corner of the delta, or of the midtap of one phase, are covered. The advantages and disadvantages of grounded vs. ungrounded systems are discussed. Information is given on how to ground the system, where the system should be grounded, and how to select equipment for the ground of the neutral circuits. Connecting the frames and enclosures of electric apparatus, such as motors, switchgear, transformers, buses, cables, conduits, building frames, and portable equipment, to a ground system is addressed. The fundamentals of making the interconnection of a ground conductor system between electric equipment and the ground rods, water pipes, etc., are outlined. The problems of static electricity— how it is generated, what processes may produce it, how it is measured, and what should be done to prevent its generation or to drain the static charges to earth to prevent sparking—are treated. Methods of protecting structures against the effects of lightning are also covered. Obtaining a low-resistance connection to earth, use of ground rods, connections to water pipes, etc., are discussed. A separate chapter on electronic equipment is included. Keywords: connection to earth, electronic equipment grounding, equipment grounding, lightning protection, static protection, system grounding The Institute of Electrical and Electronics Engineers, Inc. 3 Park Avenue, New York, NY 10016-5997, USA Copyright © 2007 by the Institute of Electrical and Electronics Engineers, Inc. All rights reserved. Published 30 November 2007. Printed in the United States of America. IEEE is a registered trademark in the U.S. Patent & Trademark Office, owned by the Institute of Electrical and Electronics Engineers, Incorporated. National Electrical Code and NEC are both registered trademarks in the U.S. Patent & Trademark Office, owned by the National Fire Protection Association. National Electrical Safety Code and NESC are both registered trademarks and service marks of the Institute of Electrical and Electronics Engineers, Inc. National Lightning Detection Network (NLDN) is a registered trademark of Vaisala, Inc. Print: PDF: ISBN 0-7381-5639-2 ISBN 0-7381-5640-X SH95700 SS95700 No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission of the publisher. IEEE Standards documents are developed within the IEEE Societies and the Standards Coordinating Committees of the IEEE Standards Association (IEEE-SA) Standards Board. The IEEE develops its standards through a consensus development process, approved by the American National Standards Institute, which brings together volunteers representing varied viewpoints and interests to achieve the final product. Volunteers are not necessarily members of the Institute and serve without compensation. While the IEEE administers the process and establishes rules to promote fairness in the consensus development process, the IEEE does not independently evaluate, test, or verify the accuracy of any of the information contained in its standards. Use of an IEEE Standard is wholly voluntary. The IEEE disclaims liability for any personal injury, property or other damage,