Electrical Grounding

Electrical Grounding

by Ronald P. O'Riley

Paperback(2nd ed)

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Product Details

ISBN-13: 9780827338531
Publisher: Cengage Delmar Learning
Publication date: 05/28/1990
Series: Electrical Trades Ser.
Edition description: 2nd ed
Pages: 274

About the Author

After serving for fours years as an electrician's mate in the US Navy during World War II, and then serving a four-year electrical apprenticeship, Ronald P. O'Reily rose through the ranks on the job to become an electrical superintendent. In the process he has accumulated over forty years of experience in the electrical industry. During the past thirty-five years he has been an instructor of electrical theory and Code classes for electrical apprentices and journeyman training, serving for many od those years as the training director of the Dallas JATC. He is a retired member of the International Brotherhood of Electrical Workers and an active associate member of the IAEI, where he has served for several years as an officer of the Texas Chapter.

Table of Contents

Prefacexi
List of NFPA Materialsxvii
Introductionxix
Chapter 1Article 250, Grounding1
Overview of Article 250, Grounding3
Definitions6
Chapter 2Electrical Theory Applicable to Grounding14
Current Flow14
The Electron15
Ohm's Law16
Direct Current17
Series Circuit17
Alternating Current19
Impedance21
Amps and Overcurrent Protective Devices21
Parallel Circuit22
Series-Parallel Circuit23
Chapter 3Grounding for Safety24
Electric Shock24
Potential Difference26
Grounding and Electric Shock27
Chapter 4Faults30
Types of Faults31
Stresses Caused by Faults32
Ionization32
Grounded-System Faults33
Impedance-Grounded Systems35
Ungrounded System Faults37
Ground Fault Detectors39
Chapter 5Grounding Electrode System40
Grounding Theory40
Responsibility of the Grounding Electrode41
The Ground Rod43
Grounding Electrode System47
Metal Water Pipe Electrodes48
Supplemental Electrodes49
Building Steel as an Electrode50
Concrete-Encased Electrodes51
Ground Ring Electrodes52
Rod and Pipe Electrodes53
Plate Electrodes53
Dwelling Unit Electrode54
Summary59
Chapter 6Grounding Electrode Conductor61
Definition of Grounding Electrode Conductor62
Materials63
Splicing63
Installation and Protection64
Connecting the Grounding Electrode Conductor68
Sizing the DC Grounding Electrode Conductor71
Sizing the AC Grounding Electrode Conductor72
Sizing Grounding Electrode Conductors74
Summary80
Chapter 7Circuit and System Grounding82
Why Ground Circuits and Systems?83
Definitions83
Direct-Current Systems85
Alternating-Current Systems86
AC Systems Not Required to Be Grounded91
High-Impedance Grounding92
Chapter 8Grounded Conductor97
Definition of Grounded Conductor97
Grounded Conductor Connection in a Direct-Current System98
Grounded Conductor Connection in an Alternating-Current System98
Bringing the Grounded Conductor to Service99
Sizing the Grounded Conductor101
Installing the Grounded Conductor105
System or Circuit Conductor to be Grounded106
Identifying the Grounded Conductor106
Grounded Conductor Overcurrent Protection108
Chapter 9Main Bonding Jumper110
Definition of Main Bonding Jumper111
Location of the Main Bonding Jumper112
Materials for the Main Bonding Jumper112
Connections114
Sizing the Main Bonding Jumper114
Chapter 10Equipment Grounding Conductor122
Definition of Equipment Grounding Conductor123
Definition of System123
Definition of Circuit125
Performance of Fault Current Path126
Types of Equipment Grounding Conductors127
Wire Used for Equipment Grounding Conductor127
Identification of Equipment Grounding Conductor128
Installation of Equipment Grounding Conductor130
Raceways as Equipment Grounding Conductors133
Earth as an Equipment Grounding Conductor142
Equipment Grounding Conductor Connections142
Equipment Grounding Conductor Continuity143
Sizing Equipment Grounding Conductors144
Equipment Grounding Conductor in Boxes151
Agricultural Buildings154
Chapter 11Equipment and Enclosure Bonding156
Definitions157
Materials159
Connections159
Bonding at Service Equipment159
Sizing Bonding Jumpers on Supply Side of Service165
Grounding Electrode Conductor Enclosure Bonding173
Flexible Metal Conduit in Service-Entrance Raceway174
Bonding Other Than at Service174
Structural Bonding Steel176
Sizing Load Side of Service Bonding Jumpers178
Bonding Grounding Electrode Systems180
Bonding Receptacles183
Bonding Lightning Protection System183
Establishing an Equipotential Plane in an Agricultural Building184
Swimming Pool Bonding Grid184
Summary187
Chapter 12Equipment and Enclosure Grounding188
Why Ground Metal Enclosures and Equipment?188
Enclosure and Raceway Grounding189
Part VI. Equipment Grounding191
Methods of Grounding Enclosures and Equipment197
Grounding Panelboards198
Isolated Equipment Grounding Receptacles200
Tower Grounding204
Computer Grounding204
Chapter 13Grounded Circuit Conductor for Grounding Equipment209
The Basic Rule210
Supply-Side Use210
Second Building211
Separately Derived System211
Load-Side Use212
Summary215
Chapter 14Ground-Fault Protective Equipment216
Ground-Fault Protection of Equipment217
Ground-Fault Protection Equipment Required at Service218
Ground-Fault Protection Equipment Required--Feeder221
Definition of Ground-Fault Circuit Interrupter221
Receptacles Requiring GFCI Protection223
Replacing Nongrounded Type Receptacles224
Arc Fault Circuit Interrupter (AFCI)232
Chapter 15System and Circuit Grounding 1 kV and Over234
Neutral Grounded Systems235
Neutral Grounded Systems Required and Permitted235
Solidly Grounded Systems237
Impedance-Grounded Systems238
Equipment Grounding239
Chapter 16Separately Derived Systems242
Definition of Separately Derived System242
Bonding Jumper245
Grounding Electrode Conductor246
Grounding Electrode247
The Grounding Electrode Conductor247
Bonding at Separately Derived Systems250
Dedicated Five-Wire System251
Portable Generators251
Vehicle-Mounted Generators251
Chapter 17Two or More Buildings Supplied by One Service254
Disconnecting Means255
Grounded and Ungrounded Systems255
Second Building Grounding Electrode System261
Sizing the Grounding Electrode Conductor at the Second Building261
Sizing the Equipment Bonding Jumper at the Second Building262
Disconnecting Means at the Second Building262
No Disconnecting Means at the Second Building263
Agricultural Buildings263
Chapter 18Calculating Fault Currents and Grounding Conductor Withstand Rating269
Introduction269
Purpose of Grounding270
Short-Circuits and Ground Faults271
Protective-Device Terms271
Important Code Requirements273
Fault-Current Path273
Available Fault Current273
Factors Affecting Amount of Fault-Current276
Transformer Secondary Current276
Transformer Impedance277
Other Factors Affecting Fault-Current Values278
Point-to-Point Calculations278
Fault-Current and Parallel Conductors281
Combining Fuse and Circuit Breaker for Protection282
Summary283
Appendix287
Index295

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