Audel ™ Guide to the 2005 National Electrical Code ® C_FM.qxd 3/9/04 10:56 Page i C_FM.qxd 3/9/04 10:56 Page i Audel ™ Guide to the 2005 National Electrical Code ® All New Edition Paul Rosenberg C_FM.qxd 3/9/04 10:56 Page i Vice President and Executive Group Publisher: Richard Swadley Vice President and Publisher: Joseph B. Wikert Executive Editor: Carol A. Long Editorial Manager: Kathryn A. Malm Development Editor: Emilie Herman Production Editor: Vincent Kunkemueller Text Design & Composition: Wiley Composition Services Copyright © 2004 by Wiley Publishing, Inc. All rights reserved. Copyright © 1999 by Macmillan USA. 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Library of Congress Control Number: Printed in the United States of America 10 98765432 C_FM.qxd 3/9/04 10:56 Page ii eISBN: 0-7645-7903-7 Contents Foreword xv Introduction xvii Article Chapter 1 General 1 100 Definitions 1 110 Requirements for Electrical Installations 1 General 3 600 Volts, Nominal or Less 12 Over 600 Volts, Nominal 16 Tunnel Installations Over 600 Volts, Nominal 21 Chapter 2 Wiring and Protection 25 200 Use and Identification of Grounded Conductors 25 210 Branch Circuits 30 General Provisions 30 Branch-Circuit Ratings 43 Required Outlets 48 215 Feeders 55 220 Branch-Circuit, Feeder, and Service Calculations 60 General 60 Feeders 63 Optional Calculations for Computing Feeder and Service Loads 71 Method for Computing Farm Loads 75 225 Outside Branch Circuits and Feeders 75 More Than One Building or Structure 84 Over 600 Volts 88 230 Services 88 General 88 Overhead Services 92 Underground Service—Lateral Conductors 97 iii C_FM.qxd 3/9/04 10:56 Page iii iv Contents Service-Entrance Conductors 98 Service Equipment—General 107 Service Equipment—Disconnecting Means 107 Service Equipment—Overcurrent Protection 115 Service Exceeding 600 Volts, Nominal 120 240 Overcurrent Protection 123 General 123 Location 127 Enclosures 134 Disconnecting and Guarding 135 Plug Fuses, Fuseholders, and Adapters 136 Cartridge Fuses and Fuseholders 138 Circuit Breakers 139 Supervised Industrial Installations 140 Overcurrent Protection Over 600 Volts, Nominal 142 250 Grounding 143 General 143 Circuit and System Grounding 147 Grounding Electrode System and Grounding Electrode Conductor 162 Grounding Conductors 166 Enclosure and Raceway Grounding 174 Bonding 175 Equipment Grounding and Equipment-Grounding Conductors 183 Methods of Equipment Grounding 190 Direct Current Systems 197 Instruments, Meters, and Relays 198 Grounding of Systems and Circuits of 1 kV and Over (High Voltage) 200 280 Surge Arresters 202 General 202 Installation 203 Connecting Surge Arresters 204 C_FM.qxd 3/9/04 10:56 Page iv Chapter 3 Wiring Methods and Materials 207 300 Wiring Methods 207 General Requirements 207 Requirements for Over 600 Volts, Nominal 225 310 Conductors for General Wiring 227 312 Cabinets and Cutout Boxes 237 Installation 237 Construction Specifications 243 314 Outlet, Device, Pull, and Junction Boxes, Conduit Bodies, Fittings, and Handhole Enclosures 244 General 244 Installation 245 Construction Specifications 261 Manholes and Other Electric Enclosures Intended for Personnel Entry 262 Pull and Junction Boxes for Use on Systems Over 600 Volts, Nominal 263 320 Armored Cable: Type AC 265 General 265 Installation 265 Construction 267 322 Flat Cable Assemblies: Type FC 268 Installation 269 Construction 270 324 Flat Conductor Cable: Type FCC 270 General 270 Installation 272 Construction 274 326 Integrated Gas Spacer Cable: Type IGS 274 328 Medium Voltage Cable: Type MV 274 330 Metal-Clad Cable: Type MC 275 General 275 Installation 275 Construction Specifications 278 Contents v C_FM.qxd 3/9/04 10:56 Page v vi Contents 332 Mineral-Insulated, Metal-Sheathed Cable: Type MI 278 General 278 Installation 280 Construction Specifications 282 334 Nonmetallic-Sheathed Cable: Types NM and NMC 283 General 283 Installation 284 Construction Specifications 287 336 Power and Control Tray Cable: Type TC 287 Installation 287 Construction Specifications 288 338 Service-Entrance Cable: Types SE and USE 289 340 Underground Feeder and Branch-Circuit Cable: Type UF 292 Installation 293 342 Intermediate Metal Conduit 294 General 294 Installation 294 Construction Specifications 297 344 Rigid Metal Conduit 297 Installation 298 Construction Specifications 302 348 Flexible Metal Conduit 303 Installation 303 Installation 305 352 Rigid Nonmetallic Conduit 308 Installation 308 354 Nonmetallic Underground Conduit with Conductors 311 General 311 Installation 311 Construction 313 356 Liquid-Tight Flexible Nonmetallic Conduit 313 General 313 Installation 313 C_FM.qxd 3/9/04 10:56 Page vi 358 Electrical Metallic Tubing 315 Installation 315 360 Flexible Metallic Tubing 317 Installation 317 362 Electrical Nonmetallic Tubing 319 General 319 Installation 319 366 Auxiliary Gutters 322 368 Busways 326 General Requirements 326 Requirements for over 600 Volts, Nominal 330 370 Cablebus 331 372 Cellular Concrete Floor Raceways 333 374 Cellular Metal Floor Raceways 334 Installation 335 376 Metal Wireways 336 378 Nonmetallic Wireways 339 380 Multioutlet Assembly 341 Installation 341 382 Nonmetallic Extensions 343 Installation 343 386 Surface Metal Raceways 348 Installation 348 388 Surface Nonmetallic Raceways 350 Installation 350 Construction Specifications 351 390 Underfloor Raceways 351 392 Cable Trays 357 394 Concealed Knob-and-Tube Wiring 372 396 Messenger-Supported Wiring 375 398 Open Wiring on Insulators 377 Chapter 4 Equipment for General Use 381 400 Flexible Cords and Cables 381 General 381 Construction Specifications 385 Portable Cables Over 600 Volts, Nominal 386 Contents vii C_FM.qxd 3/9/04 10:56 Page vii viii Contents 402 Fixture Wires 387 404 Switches 388 Installation 388 Construction Specifications 396 408 Switchboards and Panelboards 397 Switchboards 399 Panelboards 400 Construction Specifications 404 409 Industrial Control Panels 405 410 Lighting Fixtures, Lampholders, Lamps, Receptacles, and Rosettes 406 General 406 Fixture Locations 407 Provisions at Fixture Outlet Boxes, Canopies, and Pans 411 Fixture Supports 412 Grounding 414 Wiring of Fixtures 415 Construction of Fixtures 420 Installation of Lampholders 420 Construction of Lampholders 420 Lamps and Auxiliary Equipment 420 Receptacles, Cord Connectors, and Attachment Plugs (Caps) 421 Special Provisions for Flush and Recessed Fixtures 424 Construction of Flush and Recessed Fixtures 426 Special Provisions for Electric-Discharge Lighting Systems of 1000 Volts or Less 426 Special Provisions for Electric-Discharge Lighting Systems of More Than 1000 Volts 429 Lighting Track 432 411 Lighting Systems Operating at 30 Volts or Less 433 422 Appliances 434 General 434 Branch-Circuit Requirements 435 C_FM.qxd 3/9/04 10:56 Page viii [...]... damage could be done to conductor insulation by pulling too many conductors in to raceways, or by pulling around too many bends There are even times, when pulling large sizes of conductors, that the 360 degrees in total bends between pull boxes and the like could be too many Since the Code is not intended to be a design manual, it is up to the designer and the inspection authority to C_FM.qxd 3/9/04... a difficult document to comprehend In order to make the NEC more easily understood and applicable, a number of guides have been written, most of which have a legitimate place These guides serve to make all parts of the NEC understandable They are written for engineers, designers, installers, and inspectors *National Electrical Code and (NEC ®) are registered trademarks of the National Fire Protection... other independent testing laboratories are used for this purpose in many instances One of the deterrents to Code understanding can be lack of communication between the inspector and the installer Actually the inspector is the installer’s friend, and all the inspector wants is a good safe job The best advice to offer in this respect is to get acquainted with your inspector; he or she will be understanding... approximately 10 to 15 persons, the majority of them engineers Members of each committee meet several times, discuss all proposed changes, accepting some and rejecting others, and rewrite (as required) the sections of the Code that were assigned to their committee Then, they circulate the changes among the various committees, coordinate the changes, and rewrite again So, obviously, the updating of the NEC is... of the code May The word may gives you an option You can do it the certain way that is stated, or you can do it another way; it is your choice Grounded Conductor This is almost always the neutral conductor, although not necessarily Take care not to let the word grounded confuse you; “grounded conductor” does not refer to a green wire Grounding Conductor This is the green wire, more correctly called the. .. cables in the NEC is odd, since these cables carry no electricity at all They are included in the National Electrical Code for two primary reasons: (1) because they are usually installed by the same persons who install electrical wiring and (2) because optical fiber systems interact with, and depend upon, electrical and electronic systems The code s reference to “optical raceway” refers to special... instances, the Code puts the entire responsibility of interpretation on the enforcing authority For example, you will often find the phrase by special permission; this means special permission, in writing, by the Code- enforcing authority The enforcing authority is vested with the right to decide on the approval of equipment and materials However, listings from the Underwriters’ Laboratory, the CSA, or other... NEC is no small chore But the real difficulty is that it must remain applicable to all types of electrical installations, leaving no gaps Because of this, it becomes rather difficult to interpret in many instances The purpose of this book is to arrange all of the pertinent requirements of the National Electrical Code in a manner that is userfriendly, allowing the reader to find the needed information... than the Code installations This gives the enforcing authority the latitude to okay such installations C_FM.qxd 3/9/04 10:56 Page xxii xxii Introduction 90.5: Mandatory Rules, Permissive Rules and Explanatory Material The Code includes both mandatory and advisory rules The mandatory rules are characterized by the word “shall” This means that the rules must be strictly followed Any time you see the. .. material in the NEC is placed in Fine Print Notes (FPN) These notes are important for you to read, but they are not enforceable 90.6: Formal Interpretations An NEC committee is set up to render official Code interpretations when these are necessary In the majority of questions arising on the Code, the interpretations are under the inspector’s jurisdiction, as will be seen in the next section However, there . Audel ™ Guide to the 2005 National Electrical Code ® C_FM.qxd 3/9/04 10:56 Page i C_FM.qxd 3/9/04 10:56 Page i Audel ™ Guide to the 2005 National Electrical Code ® All. reject- ing others, and rewrite (as required) the sections of the Code that were assigned to their committee. Then, they circulate the changes among the various