Table of Contents. Unit 3 Magnetism Unit 1 Matter Unit 4 Electricity Unit 2 Electron Theory Unit 5 Electromagnetism...

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2 Introduction...x How to Use This Textbook...xi About the Author...xii About the Graphic Illustrator...xiii Mike Holt Enterprises Team...xiv Chapter 1 Electrical Fundamentals... 1 Unit 1 Matter... 3 Introduction Matter Atomic Theory Law of Electrical Charges Law of Atomic Charges Charged Material (Static Charge) Neutralizing a Charge Lightning Lightning Protection... 7 Summary... 9 Conclusion Practice Questions Unit 2 Electron Theory Introduction Electron Orbits Valence Electrons Freeing Electrons from an Atom Conductors Insulators Semiconductors Atomic Bonding Compounds Summary Conclusion Practice Questions Unit 3 Magnetism Introduction The Natural Magnet Magnetic Polarities Magnetic Compass Magnetic Molecule Magnetic Properties How to Magnetize Iron Permanent and Temporary Magnets Demagnetizing Magnets Magnetic Lines of Force Magnetic Materials Law of Attraction and Repulsion Retentivity Permeability Summary Conclusion Practice Questions Unit 4 Electricity Introduction Electric Current Flow (Electricity) Electricity Useful Purposes of Electricity Dangers of Electricity National Electrical Code Summary Conclusion Practice Questions Unit 5 Electromagnetism Introduction Electromagnetism in a Wire Field Intensity Field Interaction Field Interaction of Loops Mike Holt Enterprises, Inc NEC.CODE ( ) v

3 5.5 Electromagnetism in a Coil Magnetic Core Amperes and Turns Summary Conclusion Practice Questions Unit 6 Uses of Electromagnetism Introduction Basic Electric Meters Electric Motors Electrical Generators Electromagnetic Relay Summary Conclusion Practice Questions Chapter 1 Final Exam Questions Chapter 2 Basic Electricity Unit 7 The Electrical Circuit Introduction The Electrical Circuit Electron Current Flow Theory Conventional Current Flow Theory Voltage (Pressure) Resistance Electric Current Power Electrical Formulas Summary Conclusion Practice Questions Unit 8 Math Introduction Whole Numbers Decimals Fractions Percentages Multiplier Percent Increase Reciprocals Squaring a Number Square Root Volume Kilo Rounding Off Parentheses Testing Your Answer for Reasonableness Summary Conclusion Practice Questions Unit 9 Electrical Formulas Introduction Electrical Circuit Power Source Conductance Circuit Resistance Ohm s Law Ohm s Law and Alternating Current Ohm s Law Formula Circle PIE Formula Circle Formula Wheel Using the Formula Wheel Power Losses of Conductors Cost of Power Power Changes with the Square of the Voltage Summary Conclusion Practice Questions Chapter 2 Final Exam Questions Chapter 3 Basic Electrical Circuits Unit 10 Series Circuits Introduction Practical Uses of the Series Circuit Understanding Series Calculations Series Circuit Calculations Power Calculations vi Mike Holt s Illustrated Guide to Basic Electrical Theory

4 10.5 Variations Series Circuit Notes Series-Connected Power Supplies Summary Conclusion Practice Questions Unit 11 Parallel Circuits Introduction Practical Uses of the Parallel Circuits Understanding Parallel Calculations Circuit Resistance Parallel Circuit Notes Parallel-Connected Power Supplies Summary Conclusion Practice Questions Unit 12 Series-Parallel Circuits Introduction Review of Series and Parallel Circuits Working With Series-Parallel Circuits Voltage Summary Conclusion Practice Questions Unit 13 Multiwire Circuits Introduction Neutral Conductor Grounded Conductor Current Flow on the Neutral Conductor Balanced Systems Unbalanced Current Multiwire Branch Circuits Dangers of Multiwire Circuits NEC Requirements Summary Conclusion Practice Questions Chapter 3 Final Exam Questions Chapter 4 Electrical Systems and Protection Unit 14 The Electrical System Introduction Current Flow Utility Neutral Current Path Utility Ground-Fault Current Path Premises Neutral Current Path Premises Ground-Fault Current Path Utility High-Voltage Transmission Lines Conductor Voltage Drop Conductor Power Loss Reducing Voltage Drop and Power Loss Generating Plants Step-Up Substation at Generating Plant Transmission Line Step-Down Substation Primary Distribution Feeders Distribution Transformer Secondary Distribution Line Summary Conclusion Practice Questions Unit 15 Protection Devices Introduction Part A Overcurrent Protection Devices Overcurrent Protection Clearing Faults Overcurrent Protection Device Types Fuse Circuit Breaker Trip Elements Circuit Breaker Types Available Short-Circuit Current Interrupting Rating Short-Circuit Current Rating Current-Limiting Protection Part B Ground-Fault Circuit Interrupters How a GFCI Works Neutral-to-Case Detection Line-to-Neutral Shock Hazard Mike Holt Enterprises, Inc NEC.CODE ( ) vii

5 15.14 GFCI Fails Circuit Remains Energized GFCI Test Button Part C Arc-Fault Circuit Interrupters Arcing Definition Series versus Parallel Arc AFCIs and the NEC AFCIs How They Operate Part D Ground-Fault Protection of Equipment Ground-Fault Protection of Equipment Definition Summary Conclusion Practice Questions Chapter 4 Final Exam Questions Chapter 5 Alternating Current Unit 16 Alternating Current Introduction Current Flow Why Alternating Current Is Used How Alternating Current Is Produced AC Generator Waveform Sine Wave Nonsymmetrical Waveform Frequency Phase Degrees Lead or Lag Values of Alternating Current Summary Conclusion Practice Questions Unit 17 Capacitance Introduction Charged Capacitor Electrical Field Discharging a Capacitor Determining Capacitance Uses of Capacitors Phase Relationship Summary Conclusion Practice Questions Unit 18 Induction Introduction Self-Induction Induced Voltage and Applied Current Conductor AC Resistance Impedance Conductor Shape Magnetic Cores Self-Induced and Applied Voltage Current Flow Phase Relationship Uses of Induction Summary Conclusion Practice Questions Unit 19 Power Factor and Efficiency Introduction Part A Power Factor Apparent Power (Volt-Amperes) True Power (Watts) Power Factor Unity Power Factor Power Factor Formulas Cost of True Power Effects of Power Factor Part B Efficiency Efficiency Efficiency Formulas Summary Conclusion Practice Question Chapter 5 Final Exam Questions viii Mike Holt s Illustrated Guide to Basic Electrical Theory

6 Chapter 6 Motors, Generators, and Transformers Unit 20 Motors Introduction Part A Motor Basics Motor Principles Dual-Voltage AC Motors Motor Horsepower Ratings Motor Current Ratings Calculating Motor FLA Motor Starting Current Motor Running Current Motor Locked-Rotor Current (LRC) Motor Overload Protection Part B Direct-Current Motors Direct-Current Motor Principles Direct-Current Motor Types Reversing the Rotation of a DC Motor Part C Alternating-Current Motors AC Induction Motor Alternating-Current Motor Types Reversing the Rotation of an AC Motor Summary Conclusion Practice Questions Unit 22 Transformers Introduction Transformer Basics Secondary Induced Voltage Autotransformers Power Losses Harmonic Current Efficiency Transformer Turns Ratio Transformer kva Rating Current Flow Current Rating Summary Conclusion Practice Questions Chapter 6 Final Exam Questions Basic Electrical Theory Conclusion Basic Electrical Theory Final Exam Annex A Grounding and Bonding Index Unit 21 Generators Introduction Direct-Current Generator Alternating-Current Generator Three-Phase Generator Summary Conclusion Practice Questions Mike Holt Enterprises, Inc NEC.CODE ( ) ix

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8 Introduction...xv About This Textbook...xvii How to Use the National Electrical Code...xix About the Author...xxii About the Graphic Illustrator... xxiii Mike Holt Enterprises Team... xxiv ARTICLE 90 INTRODUCTION TO THE NATIONAL ELECTRICAL CODE Purpose of the NEC Scope of the NEC Code Arrangement Enforcement Mandatory Requirements and Explanatory Material Formal Interpretations Examination of Equipment for Product Safety Units of Measurement... 7 Article 90. Introduction Practice Questions... 8 CHAPTER 1 GENERAL ARTICLE 100 DEFINITIONS Definitions ARTICLE 110 REQUIREMENTS FOR ELECTRICAL INSTALLATIONS Part I. General Requirements Scope Approval of Conductors and Equipment Examination, Identification, Installation, and Use of Equipment Voltages Copper Conductors Conductor Sizes Wiring Integrity Suitable Wiring Methods Interrupting Protection Rating Circuit Impedance, Short-Circuit Current Rating, and Other Characteristics Deteriorating Agents Mechanical Execution of Work Mounting and Cooling of Equipment Conductor Termination and Splicing High-Leg Conductor Identification Arc-Flash Hazard Warning Manufacturer s Markings Identification of Disconnecting Means Available Fault Current Part II. 600V, Nominal, or Less Spaces About Electrical Equipment Guarding Enclosure Types Chapter 1. General Practice Questions CHAPTER 2 WIRING AND PROTECTION ARTICLE 200 USE AND IDENTIFICATION OF GROUNDED CONDUCTORS Part I. General Scope General Grounded Conductors Grounded Conductor Identification Use of White or Gray Color Terminal Identification Identification of Terminals Polarity ARTICLE 210 BRANCH CIRCUITS Part I. General Provisions Scope Other Articles Branch-Circuit Rating Multiwire Branch Circuits Identification for Branch Circuits Branch-Circuit Voltage Limitations Multiple Branch Circuits GFCI Protection Branch Circuits Required Arc-Fault Circuit-Interrupter Protection for Dwelling Units Guest Rooms and Guest Suites Part II. Branch-Circuit Ratings Conductor Sizing Overcurrent Protection Mike Holt Enterprises, Inc NEC.CODE ( ) v

9 Outlet Device Rating Permissible Loads Branch Circuits in Buildings with Multiple Occupancies Part III. Required Outlets General Dwelling Unit Receptacle Outlet Requirements Receptacles in Guest Rooms, Guest Suites, Dormitories, and Similar Occupancies Show Windows Heating, Air-Conditioning, and Refrigeration (HACR) Equipment Lighting Outlet Requirements ARTICLE 215 FEEDERS Scope Minimum Rating Overcurrent Protection Sizing Feeders with Common Neutral Conductor Equipment Grounding Conductor Ground-Fault Protection of Equipment Conductor Identification ARTICLE 220 BRANCH-CIRCUIT, FEEDER, AND SERVICE CALCULATIONS Part I. General Scope Application of Other Articles Calculations Part II. Branch-Circuit Load Calculations General Lighting Other Loads All Occupancies Maximum Load on a Branch Circuit Part III. Feeder and Service Calculations General General Lighting Demand Factors Commercial Show Window and Track Lighting Load Other than Dwelling Unit Receptacle Load Motor Load Fixed Electric Space-Heating Load Dwelling Unit Small-Appliance and Laundry Load Dwelling Unit Appliance Load Dwelling Unit Electric Clothes Dryer Load Dwelling Unit Electric Ranges and Cooking Appliances Commercial Kitchen Equipment Load Noncoincident Loads Feeder/Service Neutral Unbalanced Load Part IV. Optional Calculations for Computing Feeder and Service Loads Dwelling Unit Optional Load Calculation Existing Dwelling Unit Calculations Multifamily Optional Load Calculation Optional Calculation Two Dwelling Units Determining Existing Loads ARTICLE 225 OUTSIDE BRANCH CIRCUITS AND FEEDERS Part I. General Scope Other Articles Minimum Size of Conductors Luminaires Installed Outdoors Supports Over Buildings Attachment Masts as Support Clearance for Overhead Conductors Clearances from Buildings Raceways on Exterior Surfaces of Buildings or Other Structures Trees for Conductor Support Raceway Seal Part II. Buildings or Other Structures Supplied by a Feeder(s) or Branch Circuit(s) Number of Supplies Disconnecting Means Disconnect Location Maximum Number of Disconnects Grouping of Disconnects Access to Occupants Identified as Suitable for Service Equipment Identification of Multiple Feeders Disconnect Construction Rating of Disconnecting Means ARTICLE 230 SERVICES Part I. General Scope Number of Services Not to Pass Through a Building/Structure Conductors Considered Outside a Building Service Conductors Separate from Other Conductors Raceway Seals Clearance from Building Openings Vegetation as Support Part II. Overhead Service Conductors Overhead Service Conductor Size and Rating Vertical Clearance for Overhead Service Conductors Point of Attachment Means of Attachment Service Masts Used as Supports vi Mike Holt s Illustrated Guide to to Understanding the 2011 National Electrical Code, Volume 11

10 Part III. Underground Service Conductors Underground Service Conductor Size and Rating Protection Against Damage Part IV. Service-Entrance Conductors Number of Service-Entrance Conductor Sets Size and Rating Wiring Methods Spliced Conductors Protection Against Physical Damage Cable Supports Overhead Service Locations High-Leg Identification Part V. Service Equipment General Listed as Suitable for Service Equipment Part VI. Service Equipment Disconnecting Means Disconnect Requirements Number of Disconnects Grouping of Disconnects Manual or Power Operated Indicating Rating of Disconnect Connection to Terminals Connected on Supply Side of the Service Disconnect Part VII. Service Equipment Overcurrent Protection Overload Protection Required Ground-Fault Protection of Equipment ARTICLE 240 OVERCURRENT PROTECTION Part I. General Scope Definitions Protection of Equipment Protection of Conductors Protection of Flexible Cords and Fixture Wires Standard Ampere Ratings Supplementary Overcurrent Protection Ground-Fault Protection of Equipment Ungrounded Conductors Part II. Location Overcurrent Protection Location in Circuit Location of Overcurrent Devices Part III. Enclosures Damp or Wet Locations Vertical Position Part V. Plug Fuses, Fuseholders, and Adapters General Edison-Base Fuses Edison-Base Fuseholders Type S Fuses Type S Fuses, Adapters, and Fuseholders Part VI. Cartridge Fuses and Fuseholders General Classification Part VII. Circuit Breakers Method of Operation Indicating Nontamperable Markings Applications ARTICLE 250 GROUNDING AND BONDING Part I. General Scope Definitions General Requirements for Grounding and Bonding Objectionable Current Termination of Grounding and Bonding Conductors Protection of Fittings Clean Surfaces Part II. System Grounding and Bonding Systems Required to be Grounded Ungrounded Systems 50V to Less Than 100V Service Equipment Grounding and Bonding Main Bonding Jumper and System Bonding Jumper Separately Derived Systems Grounding and Bonding Buildings or Structures Supplied by a Feeder or Branch Circuit Generators Portable and Vehicle-Mounted Permanently Installed Generators High-Impedance Grounded Systems Part III. Grounding Electrode System and Grounding Electrode Conductor Grounding Electrode System Grounding Electrode Types Grounding Electrode Installation Requirements Auxiliary Grounding Electrodes Common Grounding Electrode Lightning Protection Electrode Grounding Electrode Conductor Grounding Electrode Conductor Installation Sizing Grounding Electrode Conductor Termination to the Grounding Electrode Grounding Electrode Conductor Termination Fittings Part IV. Grounding Enclosure, Raceway, and Service Cable Connections Service Raceways and Enclosures Other Enclosures Mike Holt Enterprises, Inc NEC.CODE ( ) vii

11 Part V. Bonding General Bonding Equipment for Services Intersystem Bonding Termination Bonding Other Enclosures Bonding Metal Parts Containing 277V and 480V Circuits Bonding Conductors and Jumpers Bonding of Piping Systems and Exposed Structural Metal Lightning Protection System Part VI. Equipment Grounding and Equipment Grounding Conductors Fixed Equipment Connected by Permanent Wiring Methods General Specific Equipment Fastened in Place or Connected by Permanent Wiring Methods Cord-and-Plug-Connected Equipment Types of Equipment Grounding Conductors Identification of Equipment Grounding Conductors Equipment Grounding Conductor Installation Use of Equipment Grounding Conductors Sizing Equipment Grounding Conductor Identification of Wiring Device Terminals Part VII. Methods of Equipment Grounding Replacing Nongrounding Receptacles Equipment Fastened in Place or Connected by Wiring Methods Equipment Considered Grounded Cord-and-Plug-Connected Equipment Ranges, Ovens, and Clothes Dryers Use of Neutral Conductor for Equipment Grounding Connecting Receptacle Grounding Terminal to Metal Enclosure Continuity and Attachment of Equipment Grounding Conductors in Boxes Part VIII. Direct-Current Systems Sizing Grounding Electrode Conductor ARTICLE 285 SURGE PROTECTIVE DEVICES (SPDS) Part I. General Scope Uses Not Permitted Number Required Listing Short-Circuit Current Rating Part II. Installation Location Routing of Conductors Part III. Connecting Surge protective devices Type 1 SPD Line Side of Service Equipment Type 2 SPD Feeder Circuits Type 3 SPDs Branch Circuits Chapter 2. Wiring and Protection Practice Questions CHAPTER 3 WIRING METHODS AND MATERIALS ARTICLE 300 WIRING METHODS Part I. General Scope Conductors Protection Against Physical Damage Underground Installations Protection Against Corrosion and Deterioration Raceways Exposed to Different Temperatures Not Permitted in Raceways Raceways in Wet Locations Above Grade Electrical Continuity Securing and Supporting Mechanical Continuity Splices and Pigtails Length of Free Conductors Boxes or Conduit Bodies Raceway or Cable to Open or Concealed Wiring Raceway Sizing Inserting Conductors in Raceways Supporting Conductors in Vertical Raceways Induced Currents in Ferrous Metal Enclosures and Raceways Spread of Fire or Products of Combustion Wiring in Ducts Not for Air Handling, Fabricated Ducts for Environmental Air, and Other Spaces For Environmental Air (Plenums) Panels Designed to Allow Access ARTICLE 310 CONDUCTORS FOR GENERAL WIRING Part I. General Scope Part II. Installation Uses Permitted Conductor Ampacity Part III. Construction Specification Conductor Construction and Application Conductors Conductor Identification viii Mike Holt s Illustrated Guide to Understanding the 2011 National Electrical Code, Volume 1

12 ARTICLE 312 CABINETS, CUTOUT BOXES, AND METER SOCKET ENCLOSURES Scope PART I. INSTALLATION Damp or Wet Locations Installed in Walls Repairing Gaps Enclosures Deflection of Conductors Enclosures With Splices, Taps, and Feed-Through Conductors ARTICLE 314 OUTLET, DEVICE, PULL AND JUNCTION BOXES; CONDUIT BODIES; AND HANDHOLE ENCLOSURES Part I. Scope and General Scope Nonmetallic Boxes Metal Boxes Part II. Installation Damp or Wet Locations Number of 6 AWG and Smaller Conductors in Boxes and Conduit Bodies Conductors That Enter Boxes or Conduit Bodies Boxes Recessed in Walls or Ceilings Repairing Noncombustible Surfaces Surface Extensions Support of Boxes and Conduit Bodies Outlet Box Boxes and Conduit Bodies for Conductors 4 AWG and Larger Wiring to be Accessible Handhole Enclosures ARTICLE 320 ARMORED CABLE (TYPE AC) Part I. General Scope Definition Part II. Installation Uses Permitted Uses Not Permitted Exposed Work Through or Parallel to Framing Members In Accessible Attics or Roof Spaces Bends Securing and Supporting Boxes and Fittings Conductor Ampacity Part III. Construction Specifications Construction Equipment Grounding Conductor ARTICLE 330 METAL-CLAD CABLE (TYPE MC) Part I. General Scope Definition Part II. Installation Uses Permitted Uses Not Permitted Through or Parallel to Framing Members In Accessible Attics or Roof Spaces Bends Securing and Supporting Fittings Conductor Ampacities Part III. Construction Specifications Equipment Grounding Conductor ARTICLE 334 NONMETALLIC-SHEATHED CABLE (TYPES NM AND NMC) Part I. General Scope Definition Listed Part II. Installation Uses Permitted Uses Not Permitted Exposed Through or Parallel to Framing Members Attics and Roof Spaces Bends Securing and Supporting Conductor Ampacity Part III. Construction Specifications Construction Conductors Equipment Grounding Conductor Insulation ARTICLE 338 SERVICE-ENTRANCE CABLE (TYPES SE AND USE) Part I. General Scope Definitions Part II. Installation Uses Permitted Uses Not Permitted Bends Mike Holt Enterprises, Inc NEC.CODE ( ) ix

13 ARTICLE 340 UNDERGROUND FEEDER AND BRANCH- CIRCUIT CABLE (TYPE UF) Part I. General Scope Definition Listing Requirements Part II. Installation Uses Permitted Uses Not Permitted Bends Ampacity Insulation ARTICLE 342 INTERMEDIATE METAL CONDUIT (TYPE IMC) Part I. General Scope Definition Listing Requirements Part II. Installation Uses Permitted Dissimilar Metals Trade Size Number of Conductors Bends Number of Bends (360 ) Reaming Securing and Supporting Couplings and Connectors Bushings ARTICLE 344 RIGID METAL CONDUIT (TYPE RMC) Part I. General Scope Definition Listing Requirements Part II. Installation Uses Permitted Dissimilar Metals Trade Size Number of Conductors Bends Number of Bends (360 ) Reaming Securing and Supporting Couplings and Connectors Bushings Part III. Construction Specifications Standard Lengths ARTICLE 348 FLEXIBLE METAL CONDUIT (TYPE FMC) Part I. General Scope Definition Listing Requirements Part II. Installation Uses Permitted Uses Not Permitted Trade Size Number of Conductors Bends Number of Bends (360 ) Trimming Securing and Supporting Fittings Grounding and Bonding ARTICLE 350 LIQUIDTIGHT FLEXIBLE METAL CONDUIT (TYPE LFMC) Part I. General Scope Definition Listing Requirements Part II. Installation Uses Permitted Uses Not Permitted Trade Size Number of Conductors Bends Number of Bends (360 ) Securing and Supporting Fittings Grounding and Bonding ARTICLE 352 RIGID POLYVINYL CHLORIDE CONDUIT (TYPE PVC) Part I. General Scope Definition Part II. Installation Uses Permitted Uses Not Permitted Trade Size Number of Conductors Bends Number of Bends (360 ) Trimming Securing and Supporting Expansion Fittings x Mike Holt s Illustrated Guide to Understanding the 2011 National Electrical Code, Volume 1

14 Bushings Joints Equipment Grounding Conductor ARTICLE 356 LIQUIDTIGHT FLEXIBLE NONMETALLIC CONDUIT (TYPE LFNC) Part I. General Scope Definition Listing Requirement Part II. Installation Uses Permitted Uses Not Permitted Trade Size Number of Conductors Bends Number of Bends (360 ) Securing and Supporting Fittings Equipment Grounding Conductor ARTICLE 358 ELECTRICAL METALLIC TUBING (TYPE EMT) Part I. General Scope Definition Listing Requirement Part II. Installation Uses Permitted Uses Not Permitted Trade Size Number of Conductors Bends Number of Bends (360 ) Reaming and Threading Securing and Supporting Couplings and Connectors ARTICLE 362 ELECTRICAL NONMETALLIC TUBING (TYPE ENT) Part I. General Scope Definition Part II. Installation Uses Permitted Uses Not Permitted Trade Sizes Number of Conductors Bends Number of Bends (360 ) Trimming Securing and Supporting Bushings Joints Equipment Grounding Conductor ARTICLE 376 METAL WIREWAYS Part I. General Scope Definition Part II. Installation Uses Permitted Uses Not Permitted Conductors Maximum Size Number of Conductors and Ampacity Wireway Sizing Supports Splices, Taps, and Power Distribution Blocks ARTICLE 380 MULTIOUTLET ASSEMBLIES Part I. General Scope Part II. Installation Uses Permitted Uses Not Permitted Through Partitions ARTICLE 386 SURFACE METAL RACEWAYS Part I. General Scope Definition Listing Requirements Part II. Installation Uses Permitted Uses Not Permitted Size of Conductors Number of Conductors Securing and Supporting Splices and Taps Equipment Grounding Conductor Separate Compartments ARTICLE 392 CABLE TRAYS Part I. General Scope Definition Part II. Installation Uses Permitted Uses Not Permitted Cable Tray Installations Mike Holt Enterprises, Inc NEC.CODE ( ) xi

15 Cable and Conductor Installation Number of Conductors or Cables Securing and Supporting Bushed Raceway Cable Splices Equipment Grounding Conductor Ampacity of Conductors Chapter 3. Wiring Methods And Materials Practice Questions CHAPTER 4 EQUIPMENT FOR GENERAL USE ARTICLE 400 FLEXIBLE CORDS AND FLEXIBLE CABLES Scope Suitability Types of Flexible Cords and Flexible Cables Ampacity of Flexible Cords and Flexible Cables Uses Permitted Uses Not Permitted Pull at Joints and Terminals Protection from Damage Equipment Grounding Conductor Identification ARTICLE 402 FIXTURE WIRES Scope Types Allowable Ampacity of Fixture Wires Minimum Size Raceway Size Neutral Conductor Uses Permitted Uses Not Permitted Overcurrent Protection ARTICLE 404 SWITCHES Scope Switch Connections Switch Enclosures Damp or Wet Locations Position of Knife Switches Indicating Accessibility and Grouping Switch Faceplates Mounting Snap Switches Circuit Breakers Used as Switches Grounding of Enclosures Rating and Use of Snap Switches Switch Marking ARTICLE 406 RECEPTACLES, CORD CONNECTORS, AND ATTACHMENT PLUGS (CAPS) Scope Definitions Receptacle Rating and Type General Installation Requirements Receptacle Mounting Receptacle Faceplates Attachment Plugs, Cord Connectors, and Flanged Surface Devices Receptacles in Damp or Wet Locations Connecting Receptacle Grounding Terminal to Equipment Grounding Conductor Tamper-Resistant Receptacles in Dwelling Units Tamper-Resistant Receptacles in Guest Rooms and Guest Suites Tamper-Resistant Receptacles in Child Care Facilities ARTICLE 408 SWITCHBOARDS AND PANELBOARDS Part I. General Scope Arrangement of Busbars and Conductors Field Identification Clearance for Conductors Entering Bus Enclosures Unused Openings Part III. Panelboards Overcurrent Protection of Panelboards Panelboards in Damp or Wet Locations Equipment Grounding Conductor Neutral Conductor Terminations Part IV. Construction Specifications Maximum Number of Overcurrent Devices ARTICLE 410 LUMINAIRES, LAMPHOLDERS, AND LAMPS Part I. General Scope Definitions Listing Required Part II. Luminaire Locations Luminaires in Specific Locations Luminaires Near Combustible Material Luminaires in Clothes Closets Space for Cove Lighting Part III. Luminaire Outlet Boxes and Covers Outlet Boxes to be Covered Connection of Electric-Discharge and LED Luminaires Part IV. Luminaire Supports Supports xii Mike Holt s Illustrated Guide to Understanding the 2011 National Electrical Code, Volume 1

16 Means of Support Part V. Grounding (Bonding) Methods of Grounding Part VI. Wiring of Luminaires Polarization of Luminaires Cord-Connected Luminaires Luminaires as Raceways Conductors and Ballasts Part VIII. Installation of Lampholders Screw-Shell Lampholders Lampholders in Wet or Damp Locations Lampholders Near Combustible Material Part X. Recessed Luminaires General Thermally Protected Recessed Luminaire Clearances Wiring Part XII. Electric-Discharge Lighting General Part XIV. Track Lighting Installation Fastening ARTICLE 411 LIGHTING SYSTEMS OPERATING AT 30V OR LESS Scope Definition Listing Required Specific Location Requirements Secondary Circuits ARTICLE 422 APPLIANCES Part I. General Scope Definitions Other Articles Part II. Branch-Circuit Requirements Branch-Circuit Rating Overcurrent Protection Central Heating Equipment (Furnaces) Storage Water Heaters Central Vacuums Flexible Cords Support of Ceiling Paddle Fans Part III. Disconnect General Permanently Connected Appliance Disconnects Cord-and-Plug-Connected Appliance Disconnects Unit Switches as Disconnects Cord-and-Plug-Connected Vending Machines Electric Drinking Fountains ARTICLE 424 FIXED ELECTRIC SPACE-HEATING EQUIPMENT Part I. General Scope Branch Circuits Permanently Installed Electric Baseboard Heaters with Receptacles Part III. Electric Space-Heating Equipment Disconnecting Means Part V. Electric Space-Heating Cables Clearances of Wiring in Ceilings Area Restrictions Clearance from Other Objects and Openings Installation of Cables in Concrete or Poured Masonry Floors Part VI. Duct Heaters Disconnect for Electric Duct Heater Controllers ARTICLE 430 MOTORS, MOTOR CIRCUITS, AND CONTROLLERS Part I. General Scope Definitions Table FLC versus Motor Nameplate Current Rating Marking on Controllers Motor Controller Terminal Requirements Location of Motors The Highest Rated Motor Part II. Conductor Size Single Motor Conductor Size Several Motors Conductor Size Motor Feeder Taps Part III. Overload Protection Overload Overload Sizing for Continuous-Duty Motors Use of Fuses for Overload Protection Number of Overload Devices Part IV. Branch-Circuit Short-Circuit and Ground-Fault Protection General Branch-Circuit Short-Circuit and Ground-Fault Protection Single Overcurrent Device Part V. Feeder Short-Circuit and Ground-Fault Protection Feeder Protection Mike Holt Enterprises, Inc NEC.CODE ( ) xiii

17 Part VI. Motor Control Circuits Overcurrent Protection for Control Circuits Protection of Conductors from Physical Damage Disconnect for Control Circuits Part VII. Motor Controllers Controller Rating Need Not Open All Conductors of the Circuit Controller for Each Motor Part IX. Disconnecting Means Disconnect Requirement Operation of Disconnect Marking and Mounting Readily Accessible Disconnecting Means Rating Combination Controller and Disconnect Part XIV. Tables Table Full-Load Current, Single-Phase Motors Table Full-Load Current, Three-Phase Motors ARTICLE 440 AIR-CONDITIONING AND REFRIGERATION EQUIPMENT Part I. General Scope Definitions Other Articles Marking on Hermetic Refrigerant Motor-Compressors and Equipment Ampacity and Rating Part II. Disconnecting Means Rating and Interrupting Capacity Cord-Connected Equipment Location Part III. Overcurrent Protection General Short-Circuit and Ground-Fault Overcurrent Device Size Part IV. Conductor Sizing Conductor Size for Single Motor-Compressors Part VII. Room Air Conditioners Branch-Circuit Requirements Disconnecting Means Supply Cords Leakage Current Detector-Interrupter and Arc-Fault Circuit Interrupter ARTICLE 445 GENERATORS Scope Marking Overcurrent Protection Ampacity of Conductors Disconnecting Means Generators Supplying Multiple Loads ARTICLE 450 TRANSFORMERS Part I. General Scope Overcurrent Protection Ventilation Marking Transformer Accessibility Disconnecting Means ARTICLE 480 STORAGE BATTERIES Scope Definitions Wiring and Equipment Supplied from Batteries Overcurrent Protection for Prime Movers Disconnecting Means Racks and Trays Battery Locations Chapter 4. Equipment For General Use Practice Questions FINAL EXAM A FINAL EXAM B xiv Mike Holt s Illustrated Guide to Understanding the 2011 National Electrical Code, Volume 1

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19 Introduction...xi About This Textbook...xiii How to Use the National Electrical Code...xv About the Author... xviii About the Graphic Illustrator...xix Mike Holt Enterprises Team...xx ARTICLE 90 INTRODUCTION TO THE NATIONAL ELECTRICAL CODE Purpose of the NEC Scope of the NEC Code Arrangement Enforcement Mandatory Requirements and Explanatory Material Formal Interpretations Examination of Equipment for Product Safety Units of Measurement... 7 PRACTICE QUESTIONS FOR ARTICLE 90 INTRODUCTION... 8 CHAPTER 5 SPECIAL OCCUPANCIES ARTICLE 500 HAZARDOUS (CLASSIFIED) LOCATIONS Scope Articles 500 Through Definitions Other Articles General Classifications of Locations Material Groups Protection Techniques Equipment Specific Occupancies ARTICLE 501 CLASS I HAZARDOUS (CLASSIFIED) LOCATIONS Part I. General Scope Part II. Wiring Wiring Methods Raceway and Cable Seals Conductor Insulation Grounding and Bonding Part III. Equipment Transformers and Capacitors Meters, Instruments, and Relays Enclosures Control Transformers and Relays Motors Luminaires Utilization Equipment Flexible Cords Receptacles and Attachment Plugs Limited-Energy and Communications Systems ARTICLE 502 CLASS II HAZARDOUS (CLASSIFIED) LOCATIONS Part I. General Scope Explosionproof Equipment Part II. Wiring Wiring Methods Seals Grounding and Bonding Part III. Equipment Switches, Circuit Breakers, Motor Controllers, and Fuses Control Transformers Motors Luminaires Flexible Cords Receptacles and Attachment Plugs Limited-Energy and Communications Systems ARTICLE 503 CLASS III HAZARDOUS (CLASSIFIED) LOCATIONS Part I. General Scope General Part II. Wiring Wiring Methods Grounding and Bonding Part III. Equipment Switches, Circuit Breakers, Motor Controllers, and Fuses Control Transformers Motors Luminaires Flexible Cords Receptacles and Attachment Plugs Mike Holt Enterprises, Inc NEC.CODE ( ) v

20 Limited-Energy and Communications Systems ARTICLE 511 COMMERCIAL GARAGES, REPAIR, AND STORAGE Scope Definitions Classification of Hazardous Areas Wiring and Equipment in Hazardous (Classified) Locations Wiring and Equipment Above Hazardous (Classified) Locations Seals Special Equipment GFCI-Protected Receptacles ARTICLE 514 MOTOR FUEL DISPENSING FACILITIES Scope Definition Classification of Locations Wiring and Equipment Within Class I Locations Wiring and Equipment Above Class I Locations Underground Wiring Raceway Seal Circuit Disconnect Maintenance and Service of Dispensing Equipment Grounding and Bonding ARTICLE 517 HEALTH CARE FACILITIES Part I. General Scope Definitions Part II. Wiring and Protection Applicability Wiring Methods Grounding of Equipment in Patient Care Areas Receptacles With Insulated Grounding Terminals General Care Areas Part VI. Communications and Signaling Systems Patient Care Areas Other-Than-Patient-Care Areas ARTICLE 518 ASSEMBLY OCCUPANCIES Scope General Classifications Other Articles Wiring Methods ARTICLE 525 CARNIVALS, CIRCUSES, FAIRS, AND SIMILAR EVENTS Part I. General Requirements Scope Definitions Other Articles Overhead Conductor Clearances Protection of Electrical Equipment Part II. Power Sources Services Multiple Sources of Supply Wiring Methods Rides, Tents, and Concessions Outdoor Portable Distribution or Termination Boxes GFCI-Protected Receptacles and Equipment Part IV. Grounding and Bonding Equipment Bonding Equipment Grounding Equipment Grounding Conductor Continuity Assurance ARTICLE 547 AGRICULTURAL BUILDINGS Scope Definitions Wiring Methods Luminaires Equipotential Planes and Bonding of Equipotential Planes ARTICLE 550 MOBILE HOMES, MANUFACTURED HOMES, AND MOBILE HOME PARKS Part I. General Scope Definitions General Requirements Receptacle Outlets AFCI Protection Part III. Services and Feeders Distribution Systems Allowable Demand Factors Disconnect Feeder ARTICLE 555 MARINAS AND BOATYARDS Scope Definitions Ground-Fault Protection Transformers Location of Service Equipment Electrical Connections Electrical Equipment Enclosures Load Calculations for Service and Feeder Conductors Wiring Methods and Installation Grounding Boat Receptacle Disconnecting Means Receptacles vi Mike Holt s Illustrated Guide to Understanding the 2011 National Electrical Code, Volume 2

21 Motor Fuel Dispensing Stations Hazardous (Classified) Locations Repair Facilities ARTICLE 590 TEMPORARY INSTALLATIONS Scope All Installations Time Constraints General Listing of Decorative Lighting Ground-Fault Protection for Personnel PRACTICE QUESTIONS FOR CHAPTER 5 SPECIAL OCCUPANCIES CHAPTER 6 SPECIAL EQUIPMENT ARTICLE 600 ELECTRIC SIGNS AND OUTLINE LIGHTING Part I. General Scope Definitions Listing Markings Branch Circuits Disconnecting Means Grounding and Bonding Location Portable or Mobile Signs Ballasts, Transformers, and Electronic Power Supplies Class 2 Power Sources LED Sign Illumination Systems, Secondary Wiring ARTICLE 604 MANUFACTURED WIRING SYSTEMS Scope Definition Uses Permitted Construction Securing and Supporting ARTICLE 620 ELEVATORS, ESCALATORS, AND MOVING WALKS Part I. General Scope Part III. Wiring Branch Circuit for Machine Room/Machinery Space Branch Circuit for Hoistway Pit Part IV. Installation of Conductors Wiring in Elevator Hoistways and Machine Rooms Part VI. Disconnecting Means and Control Disconnecting Means Part VIII. Machine Rooms, Control Rooms, Machinery Spaces, and Control Spaces GFCI-Protected Receptacles ARTICLE 625 ELECTRIC VEHICLE CHARGING SYSTEM Part I. General Scope Definitions Listed or Labeled Part III. Equipment Construction Electric Vehicle Supply Equipment Rating Markings Part IV. Control and Protection Overcurrent Protection Disconnecting Means Personnel Protection System Part V. Electric Vehicle Supply Equipment Locations Indoor Sites Outdoor Sites ARTICLE 640 AUDIO SIGNAL PROCESSING, AMPLIFICATION, AND REPRODUCTION EQUIPMENT Part I. General Scope Definitions Locations and Other Articles Protection of Electrical Equipment Mechanical Execution of Work Grounding and Bonding Wiring Methods Audio Systems Near Bodies of Water Part II. Permanent Audio System Installations Use of Flexible Cords and Flexible Cables Wiring of Equipment Racks Number of Conductors in a Raceway Loudspeakers in Fire-Resistance-Rated Partitions, Walls, and Ceilings ARTICLE 645 INFORMATION TECHNOLOGY EQUIPMENT Scope Definitions Other Articles Information Technology Equipment Room Supply Circuits and Interconnecting Cables Cables Not in Information Technology Equip ment Room Penetrations Disconnecting Means Uninterruptible Power Supplies (UPS) Equipment Grounding Conductor Mike Holt Enterprises, Inc NEC.CODE ( ) vii

22 ARTICLE 680 SWIMMING POOLS, SPAS, HOT TUBS, FOUNTAINS, AND SIMILAR INSTALLATIONS Part I. General Requirements for Pools, Spas, Hot Tubs, and Fountains Scope Definitions Other Articles Cord-and-Plug-Connected Equipment Overhead Conductor Clearance Electric Water Heater Underground Wiring Equipment Rooms and Pits Maintenance Disconnecting Means Part II. Permanently Installed Pools, Outdoor Spas, and Outdoor Hot Tubs General Motors Lighting, Receptacles, and Equipment Underwater Luminaires Junction Box, Transformer, or GFCI Enclosure Feeders Equipotential Bonding Specialized Equipment Part III. Storable Swimming Pools General Pumps GFCI-Protected Receptacles Receptacle Locations Part IV. Spas and Hot Tubs General Emergency Switch for Spas and Hot Tubs Outdoor Installations Indoor Installations GFCI Protection Part V. Fountains General Luminaires, Submersible Pumps, and Other Submersible Equipment Bonding Methods of Equipment Grounding Cord-and-Plug-Connected Equipment Signs in or Adjacent to Fountains GFCI-Protected Receptacles Part VII. Hydromassage Bathtubs General GFCI Protection Other Electrical Equipment Accessibility Equipotential Bonding ARTICLE 690 SOLAR PHOTOVOLTAIC (PV) SYSTEMS *This article is covered in Mike Holt s Illustrated Guide to Understanding NEC Requirements for Solar Photovoltaic Systems. ARTICLE 695 FIRE PUMPS Scope Power Source(s) Continuity of Power Transformers Power Wiring Voltage Drop Control Wiring PRACTICE QUESTIONS FOR CHAPTER 6 SPECIAL EQUIPMENT CHAPTER 7 SPECIAL CONDITIONS ARTICLE 700 EMERGENCY SYSTEMS Part I. General Scope Definitions Tests and Maintenance Capacity Transfer Equipment Signs Part II. Circuit Wiring Wiring Part III. Sources of Power General Requirements Part IV. Circuits for Lighting and Power Loads on Emergency Branch Circuits Emergency Illumination Part VI. Overcurrent Protection Accessibility Ground-Fault Protection of Equipment Coordination ARTICLE 701 LEGALLY REQUIRED STANDBY SYSTEMS Part I. General Scope Definitions Tests and Maintenance Capacity and Rating Transfer Equipment Signs Part II. Circuit Wiring Wiring viii Mike Holt s Illustrated Guide to Understanding the 2011 National Electrical Code, Volume 2

23 Part III. Sources of Power General Requirements Part IV. Overcurrent Protection Accessibility Ground-Fault Protection of Equipment Coordination ARTICLE 702 OPTIONAL STANDBY SYSTEMS Part I. General Scope Definition Capacity and Rating Transfer Equipment Signs Part II. Circuit Wiring Wiring Outdoor Generator Sets ARTICLE 725 REMOTE-CONTROL, SIGNALING, AND POWER-LIMITED CIRCUITS Part I. General Scope Definitions Other Articles Electrical Equipment Behind Access Panels Mechanical Execution of Work Abandoned Cable Safety-Control Equipment Circuit Requirements Part II. Class 1 Circuit Requirements Class 1 Circuit Classifications and Power-Supply Requirements Class 1 Circuit Overcurrent Protection Class 1 Circuit Wiring Methods Conductors of Different Circuits in Same Cable, Cable Tray, Enclosure, or Raceway Class 1 Circuit Conductors Number of Conductors in a Raceway Part III. Class 2 and Class 3 Circuit Requirements Power Sources for Class 2 and Class 3 Circuits Equipment Marking Wiring Methods on Supply Side of the Class 2 or Class 3 Power Source Wiring Methods on Load Side of the Class 2 or Class 3 Power Source Separation from Power Conductors Conductors of Different Circuits in Same Cable, Enclosure, Cable Tray, or Raceway Support Applications of Class 2 and Class 3 Cables Part VI. Listing Requirements Listing and Marking Requirements of Class 2 and Class 3 Cables and Raceways ARTICLE 760 FIRE ALARM SYSTEMS Part I. General Scope Definitions Other Articles Access to Electrical Equipment Behind Panels Designed to Allow Access Mechanical Execution of Work Abandoned Cable Fire Alarm Circuit Identification Fire Alarm Circuit Cables Extending Beyond a Building Fire Alarm Circuit Requirements Part III. Power-Limited Fire Alarm (PLFA) Circuits Power Sources for Power-Limited Fire Alarm Circuits Equipment Marking Wiring Methods on Load Side of Power-Limited Fire Alarm Power Source Separation from Power Conductors Power-Limited Fire Alarm Circuits, Class 2, Class 3, and Communications Circuits Support Applications of Power-Limited Fire Alarm Cables (PLFA) Part IV. Listing Requirements Listing and Marking Requirements of Power-Limited Fire Alarm Cables (PLFA) ARTICLE 770 OPTICAL FIBER CABLES AND RACEWAYS Part I. General Scope Definitions Other Articles Innerduct Access to Electrical Equipment Behind Panels Designed to Allow Access Mechanical Execution of Work Abandoned Cable Spread of Fire or Products of Combustion Part II. Cables Outside and Entering Buildings Unlisted Cables Entering Buildings Part V. Installation Methods Within Buildings Raceways for Optical Fiber Cables Installation of Optical Fiber Cables, Optical Fiber Raceways, and Cable Routing Assemblies Mike Holt Enterprises, Inc NEC.CODE ( ) ix

24 Installation of Optical Fiber Cables Applications of Optical Fiber Cables and Raceways Listing and Marking of Optical Fiber Cables PRACTICE QUESTIONS FOR CHAPTER 7 SPECIAL CONDITIONS CHAPTER 8 COMMUNICATIONS SYSTEMS ARTICLE 800 COMMUNICATIONS CIRCUITS Part I. General Scope Definitions Installation of Equipment Access to Electrical Equipment Behind Panels Designed to Allow Access Mechanical Execution of Work Abandoned Cable Spread of Fire or Products of Combustion PART II. Cables Outside and Entering Buildings Overhead (Aerial) Communications Cables Underground Communications Wires and Cables Entering Buildings Unlisted Cables Entering Buildings Lightning Conductors Part III. Protection Primary Protection Grounding or Interruption of Metallic Sheath Members of Communications Cables Part IV. Grounding Methods Cable and Primary Protector Bonding and Grounding Part V. Installation Methods Within Buildings Raceways for Communications Wires and Cables Installation of Communications Cables and Communications Raceways Installation of Communications Cables Applications of Communications Cables and Communications Raceways Dwelling Unit Communications Outlet Part VI. Listing Requirements Listing and Marking of Communications Cables ARTICLE 810 RADIO AND TELEVISION EQUIPMENT Part I. General Scope Other Articles Community Television Antenna Part II. Receiving Equipment Antenna Systems Support of Lead-In Cables Avoid Contact with Conductors of Other Systems Metal Antenna Supports Grounding Clearances Antenna Discharge Unit Bonding Conductor or Grounding Electrode Conductors Part III. Amateur and Citizen Band Transmitting and Receiving Antenna Systems Other Sections Clearance on Building Antenna Discharge Units Bonding Conductor or Grounding Electrode Conductors ARTICLE 820 COMMUNITY ANTENNA TELEVISION (CATV) AND RADIO DISTRIBUTION SYSTEMS Part I. General Scope Definitions Locations and Other Articles Power Limitations Access to Electrical Equipment Behind Panels Designed to Allow Access Mechanical Execution of Work Abandoned Cable Spread of Fire or Products of Combustion Part II. Coaxial Cables Outside and Entering Buildings Unlisted Cables and Raceways Entering Building Part III. Protection Grounding of the Outer Conductive Shield of Coaxial Cables Part IV. Grounding Methods Bonding and Grounding Methods Part V. Installation Methods Within Buildings Raceways for Coaxial Cables Installation of Coaxial Cables Installation of Coaxial Cables and Equipment Applications of Coaxial Cables Listing and Marking of Coaxial Cables PRACTICE QUESTIONS FOR CHAPTER 8 COMMUNICATIONS SYSTEMS FINAL EXAM A QUESTIONS FINAL EXAM B QUESTIONS INDEX x Mike Holt s Illustrated Guide to Understanding the 2011 National Electrical Code, Volume 2

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