MIL-HDBK-419A Grounding, Bonding, and Shielding for ...

1 MIL-HDBK-419A29 DECEMBER 1987 SUPERSEDINGMIL-HDBK-41921 JANUARY 1982 MILITARY HANDBOOKGROUNDING, BONDING, AND SHIELDINGFORELECTRONIC EQUIPMENTS AND FACILITIESVOLUME I OF 2 VOLUMESBASIC THEORYAMSC N/AEMCS/SLHC/TCTSDISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimitedDEPARTMENT OF DEFENSEWASHINGTON DC 20301 MIL-HDBK-419 AGROUNDING, BONDING, AND Shielding FOR ELECTRONIC EQUIPMENTS AND standardization handbook was developed by the Department of Defense in accordance withestablished publication was approved on 29 December 1987 for printing and inclusion in the militarystandardization handbook lines and asterisks are not used in this revision to identify changeswith respect to the previous issue due to the extensiveness of the document provides basic and application information on grounding, bonding.

2 And shieldingpractices recommended for electronic will provide valuable information and guidance topersonnel concerned with the preparation of specifications and the procurement of electrical and electronicequipment for the Defense Communications handbook is not intended to be referenced in purchasespecifications except for informational purposes, nor shall it supersede any specification effort has been made to reflect the latest information on the interrelation of considerationsof electrochemistry, metallurgy, electromagnetics, and atmospheric physics. It is the intent to review thishandbook periodically to insure its completeness and currency. Users of this document are encouraged to reportany errors discovered and any recommendations for changes or inclusions to: Commander, 1842 EEG/EEITE,Scott AFB IL of Federal and Military Standards, Specifications and associated documents (including thishandbook) listed in the Department of Defense Index of Specifications and Standards (DODISS) should beobtained from the DOD Single Stock Point.

3 Commanding Officer, Naval Publications and Forms Center, 5801 Tabor Avenue, Philadelphia PA copies may be obtained on an emergency basis by calling(AUTOVON) 442-3321 or Area Code (215) of industry association documents should beobtained from the of all other listed documents should be obtained from the contractingactivity or as directed by the contracting volume is one of a two-volume series which sets forth the grounding, bonding, and Shielding theory forcommunications electronics (C-E) equipments and , bonding, and Shielding are complexsubjects about which in the past there has existed a good deal of misunderstanding. The subjects themselves areinterrelated and involve considerations of a wide range of topics from electrochemistry and metallurgy toelectromagnetic field theory and atmospheric two volumes reduce these varied considerationsinto a usable set of principles and practices which can be used by all concerned with, and responsible for, thesafety and effective operation of complex C-E possible, the principles are reduced to of the large number of interrelated factors, specific steps cannot be set forth for every , once the requirements and constraints of a given situation are defined, the appropriatesteps for solution of the problem can be formulated utilizing the principles set volumes (Volume I, Basic Theory and Volume II, Applications)

4 Implement the Grounding, Bonding, andShielding requirements of MIL-STD-188-124A which is mandatory for use within the Department of purpose of this standard is to ensure the optimum performance of ground-based telecommunicationsequipment by reducing noise and providing adequate protection against power system faults and handbook emphasizes the necessity for including considerations of grounding, bonding, and Shielding in allphases of design, construction, operation, and maintenance of electronic equipment and facilities. Volume I,Basic Theory, develops the principles of personnel protection, fault protection, lightning protection,interference reduction, and EMP protection for C-E addition, the basic theories of earthconnections, signal grounding, electromagnetic Shielding , and electrical bonding are presented. The subjects arenot covered independently, rather they are considered from the standpoint of how they influence the design ofthe earth electrode subsystem of a facility, the selection of ground reference networks for equipments andstructures, Shielding requirements, facility and equipment bonding practices, I also provides thebasic background of theory and principles that explain the technical basis for the recommended practices andprocedures.

5 Illustrates the necessity for care and thoroughness in implementation of grounding, bonding, andshielding, and provides supplemental information to assist in the solution of those problems and situations notspecifically Volume II, Applications, the principles and theories, including RED/BLACK protection, are reduced to thepractical steps and procedures which are to be followed in structural and facility development, electronicengineering, and in equipment applications should assure personnel equipment andstructural safety, minimize electromagnetic interference (EMI) problems in the final operating system; andminimize susceptibility to and generation of undesirable emphasis in Volume II goes beyonddevelopment to assembly and construction, to installation and checkout, and to maintenance for long term appendices are provided as common elements in both A is a glossary of selected wordsand terms as they are used not defined in the glossary, usage is in accordance with Federal Standard1037, Glossary of Telecommunication Terms.

6 Appendix B is a supplemental bibliography containing selectedreferences intended to supply the user with additional C contains the table of contents forthe other volume. Appendix D contains the index for the two-volume OF CONTENTSCHAPTER 1 - FACILITY GROUND REFERENCED Facility Ground Grounding and Power Distribution Electrical Noise in Communications BONDING, Shielding , AND GROUNDING GROUNDING SAFETY 2 - EARTHING AND EARTH electrode of to Electrical Code of Defense Communications Electronics Resistivity OF SOIL ..Measurement OF EARTH electrode Horizontal OF CONTENTS (Continued) Frameworks of Isolated Commonly Used of Multiple Vertical Rods in Array of Vertical Grid (Mesh).

7 Rods Connected by a Impedance of of Nonhomogeneous (Layered) OF RESISTANCE-TO-EARTH OF electrode (Triangulation) Voltages Above Earth Voltage Safety Voltages for Practical Vertical Vertical Horizontal Step of State electrode OF CONTENTS (Continued) electrode Water .. Chemical electrode Salting .. CATHODIC Protection Sacrifical .. Corrosive .. GROUNDING IN ARCTIC Soil Improving Electrical Grounding in Frozen electrode .. Installation and Measurement electrode 3 - LIGHTNING PROTECTION THE PHENOMENON OF DEVELOPMENT OF A LIGHTNING INFLUENCE OF STRUCTURE STRIKE ATTRACTIVE Structures Less Than 100 Meters Cone of LIGHTNING Flash Mechanical and Thermal Electrical Conductor Impedance Induced Voltage Capacitively-Coupled Earth BASIC PROTECTION DETERMINING THE NEED FOR Strike 3-26 PageiiiMIL-HDBK-419 ATABLE OF CONTENTS (Continued) of to System 4 -FAULT PROTECTION System (GFCI).

8 EARTH POWER LINE 5 - GROUNDING OF SIGNAL REFERENCE CONDUCTOR Direct Current Alternating Current Skin AC Proximity Resistance Properties vs Impedance Effects of Stranded Rectangular Tubular Structural Steel SIGNAL REFERENCE SUBSYSTEM NETWORK Floating Single-Point Ground (for Lower Frequencies).. Multipoint Ground (for Higher Frequencies).. Equipotential Types of Equipotential Floating OF CONTENTS (Continued) SITE Lower Frequency Higher Frequency Frequency 6 - INTERFERENCE COUPLING AND COUPLING Conductive Free-Space Near-Field Inductive Capacitive Far-Field COMMON-MODE Basic Theory of Common-Mode Differential MINIMIZATION Reduction of Reference Plane Impedance Spatial Reduction of Circuit Loop Balanced Alternate FACILITY AND EQUIPMENT 6-25 CHAPTER 7 - DEFINITION OF PURPOSES OF RESISTANCE

9 DIRECT Contact Surface Surface Contact Bond Direct Bonding Soft Conductive Comparison of INDIRECT Frequency Skin Bond Stray SURFACE Solid Organic Platings and Inorganic Corrosion COMPLETION OF THE BOND Chemical Basis of Electrochemical Galvanic Relative Area of Anodic Protective SUMMARY OF 7-37 CHAPTER 8 - FUNCTION OF AN ELECTROMAGNETIC BASIC Shielding Oppositely Induced Transmission Line Nonuniform 8-4 MIL-HDBK-419 ATABLE OF CONTENTS (Continued)ParagraphPageviMIL-HDBK-419 ATABLE OF CONTENTS (Continued) EFFECTIVENESS OF CONTINUOUS SINGLE-THICKNESS Impedance Wave Impedance Correction Shielding EFFECTIVENESS OF OTHER Solid and Thin-Film and Perforated Metal DISCONTINUITY EFFECTS (APERTURES).

10 Seams Without With and Conducting OF Shielding OF CONVENTIONAL BUILDING Steel (Rebar)..CABLE AND CONNECTOR and ENCLOSURES (SCREEN ROOMS)..Demountable (Modular) Built Room OF Impedance Magnetic Field Testing Using Small Test PROTECTION OF Shielding Environmental EMI OF CONTENTS (Continued) DESIGN 9 - PERSONNEL of Electric FREQUENCY (RF) RADIATION 10 - NUCLEAR EMP EMP High-Altitude EMP (HEMP).. Early-Time Late-Time HEMP (MHDEMP).. Intermediate-Time Surface-Burst Other EMP Comparison With HEMP INTERACTION WITH Current in Long Long Overhead Long Buried Vertical HEMP Interaction With Local Penetrating 10-11 PageviiiMIL-HDBK-419 AParagraphTABLE OF CONTENTS (Continued) PROTECTION AGAINST HEMP.