Table of Contents. CHAPTER 1 BASIC ELECTRICAL THEORY (Essential for Journeyman and Master s Licensing Exams)... 1

Transcription

1 Introduction... x About This Textbook...xi Passing Your Exam...xiv How to Use the National Electrical Code... xviii About the Author...xxi About the Graphic Illustrator...xxii Mike Holt Enterprises Team... xxiii CHAPTER 1 BASIC ELECTRICAL THEORY (Essential for Journeyman and Master s Licensing Exams)... 1 UNIT 1 ELECTRICIAN S MATH AND BASIC ELECTRICAL FORMULAS...3 Part A Electrician s Math Whole Numbers Decimals Fractions Percentages Multiplier Percent Increase Reciprocals Squaring a Number Parentheses Square Root Volume Kilo Rounding Off Testing Your Answer for Reasonableness... 9 Part B Basic Electrical Formulas 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 Conclusion to Unit Practice Questions for Unit Challenge Questions for Unit UNIT 2 ELECTRICAL CIRCUITS Part A Series Circuits Practical Uses of the Series Circuit Understanding Series Calculations Series Circuit Calculations Power Calculations Variations Series Circuit Notes Series-Connected Power Supplies Part B Parallel Circuits Practical Uses of the Parallel Circuit Understanding Parallel Calculations Circuit Resistance Parallel Circuit Notes Parallel-Connected Power Supplies Part C Series-Parallel Circuits Review of Series and Parallel Circuits Working With Series-Parallel Circuits Voltage Part D Multiwire Branch Circuits Neutral Conductor Grounded Conductor Current Flow on the Neutral Conductor Balanced Systems Unbalanced Current Multiwire Branch Circuits Dangers of Multiwire Branch Circuits NEC Requirements Conclusion to Unit Practice Questions for Unit Challenge Questions for Unit v

2 UNIT 3 UNDERSTANDING ALTERNATING CURRENT Part A Understanding Alternating Current Current Flow Why Alternating Current Is Used How Alternating Current Is Produced Alternating-Current Generator Waveform Sine Wave Frequency Phase Degrees Lead or Lag Values of Alternating Current Part B Capacitance Charged Capacitor Electrical Field Discharging a Capacitor Determining Capacitance Uses of Capacitors Phase Relationship Part C Induction Self-Induction Induced Voltage and Applied Current Conductor Alternating-Current Resistance Conductor Shape Magnetic Cores Self-Induced and Applied Voltage Inductive Reactance Phase Relationship Uses of Induction Part D 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 E Efficiency Efficiency Formulas Conclusion to Unit Practice Questions for Unit Challenge Questions for Unit UNIT 4 MOTORS AND TRANSFORMERS Part A Motor Basics Motor Principles Dual-Voltage Alternating-Current Motors Motor Horsepower Ratings Motor Current Ratings Calculating Motor FLA Motor-Starting Current Motor-Running Current Motor Locked-Rotor Current (LRC) Motor Overload Protection Direct-Current Motor Principles Direct-Current Motor Types Reversing the Rotation of a Direct-Current Motor Alternating-Current Induction Motor Alternating-Current Motor Types Reversing the Rotation of an Alternating-Current Motor Part B Transformers Transformer Basics Secondary Induced Voltage Efficiency Transformer Turns Ratio Autotransformers Power Losses Transformer kva Rating Current Flow Current Rating Conclusion to Unit Practice Questions for Unit Challenge Questions for Unit CHAPTER 2 NEC CALCULATIONS (Essential for Journeyman and Master s Licensing Exams) UNIT 5 RACEWAY AND BOX CALCULATIONS Part A Raceway Fill Understanding the NEC, Chapter 9 Tables Raceway Calculations Wireways Tips for Raceway Calculations Part B Outlet Box Fill Calculations [314.16] Sizing Box Conductors All the Same Size [Table (A)] vi Mike Holt s Illustrated Guide to to Electrical Exam Preparation 2011 Edition

3 5.6 Conductor Equivalents Outlet Box Sizing [314.16(B)] Part C Pull Boxes, Junction Boxes, and Conduit Bodies Pull/Junction Box Sizing Requirements Pull/Junction Box Sizing Tips Pull Box Examples Summary Conclusion to Unit Practice Questions for Unit Challenge Questions for Unit UNIT 6 CONDUCTOR SIZING AND PROTECTION CALCULATIONS Part A General Conductor Requirements Conductor Insulation [Table (A)] Conductor Sizing [110.6] Smallest Conductor Size [ (A)] Conductor Size Terminal Temperature Rating [110.14(C)] Conductors in Parallel NEC Requirements for Conductors in Parallel [310.10(H)] Overcurrent Protection [Article 240] Overcurrent Protection of Conductors General Requirements [240.4] Overcurrent Protection of Conductors Specific Requirements Part B Conductor Ampacity Conductor Ampacity Ambient Temperature Correction Factors [Table (B)(2)(a)] Conductor Bundling Ampacity Adjustment Factors [Table (B)(3)(a)] Ambient and Conductor Bundling Adjustment Current-Carrying Conductors Wireway Conductor Ampacity [376.22(B)] Conductor Sizing Summary Part C Article 690 Solar PV systems Maximum Voltage [690.7] Circuit Sizing and Protection [690.8] Overcurrent Protection [690.9] Conclusion to Unit Practice Questions for Unit Challenge Questions for Unit UNIT 7 MOTOR AND AIR-CONDITIONING CALCULATIONS Part A Motor Calculations Scope of Article FLC versus Motor Nameplate Highest Rated Motor [430.17] Branch-Circuit Conductor Size Feeder Conductor Size [430.24] Overload Protection [430.6(A)(2) and (A)] Branch-Circuit Short-Circuit and Ground-Fault Protection [430.51] Branch-Circuit Summary Feeder Protection [430.62] Motor VA Calculations Part B Air-Conditioning Calculations Scope of Article Other Articles Short-Circuit and Ground-Fault Protection Conductor Sizing for a Single Motor-Compressor Conclusion to Unit Practice Questions for Unit Challenge Questions for Unit UNIT 8 VOLTAGE-DROP CALCULATIONS Part A Conductor Resistance Calculations Conductor Resistance Conductor Resistance Direct-Current Circuits [Chapter 9, Table 8] Conductor Resistance Alternating-Current Circuits Alternating-Current Resistance Alternating-Current Resistance as Compared to Direct-Current Resistance Part B Voltage-Drop Considerations NEC Voltage-Drop Recommendations Determining Circuit Conductors Voltage Drop Ohm s Law Method Determining Circuit Conductors Voltage Drop Formula Method Sizing Conductors to Prevent Excessive Voltage Drop Limiting Conductor Length to Minimize Voltage Drop Limiting Current to Limit Voltage Drop Conclusion to Unit Practice Questions For Unit Challenge Questions For Unit UNIT 9 DWELLING UNIT CALCULATIONS Part A General Requirements General Requirements Voltages [220.5(A)] Fraction of an Ampere [220.5(B)] vii

4 9.4 Lighting and Receptacles Cooking Equipment Branch Circuit [Table , Note 4] Part B Standard Method Feeder/Service Load Calculations Dwelling Unit Feeder/Service Load Calculations (Article 220, Part III) Dwelling Unit Example Part C Optional Method Feeder/Service Load Calculations Dwelling Unit Optional Calculations [220.82] Optional Calculation Example Part D Other Topics of Interest Neutral Calculations [220.61] Grounding and Bonding of Service Equipment Conclusion to Unit Practice Questions for Unit Challenge Questions For Unit CHAPTER 3 ADVANCED NEC CALCULATIONS (Essential for Master s Exams) UNIT 10 MULTIFAMILY DWELLING CALCULATIONS Multifamily Dwelling Calculations General Multifamily Dwelling Calculation Examples Standard Method Part A Standard Method Feeder/Service Load Calculations Multifamily Dwelling Calculations Standard Method Example Part B Optional Method Feeder/Service Load Calculations Multifamily Dwelling Unit Calculations [220.84] Optional Method Multifamily Optional Method Example 1 [220.84] Multifamily Optional Method Example 2 [220.84] Two-Family Dwelling Units [220.85] Conclusion to Unit Practice Questions for Unit Challenge Questions for Unit UNIT 11 COMMERCIAL CALCULATIONS Part A General General Requirements Conductor Ampacity [Article 100] Conductor Overcurrent Protection [240.4] Voltages [220.5(A)] Fractions of an Ampere [220.5(B)] Lighting Demand Factors [Tables and ] Lighting Without Demand Factors [215.2(A) (1), (A)(1), and Table ] Sign Circuit [220.14(F) and 600.5] Lighting Miscellaneous Multioutlet Receptacle Assembly [220.14(H)] Receptacle VA Load Banks and Offices General Lighting and Receptacles [220.14(K)] Part B Examples Bank/Office Building Example Mobile/Manufactured Home Park [550.31] Recreational Vehicle Park [551.73] Marina [555.12] Part C Optional Method Feeder/Service Load Calculations New Restaurant Optional Method [220.88] Part D Welders Arc Welders Resistance Welders Light Industrial Calculation Conclusion to Unit Practice Questions for Unit Challenge Questions for Unit UNIT 12 TRANSFORMER CALCULATIONS Part A General Transformer Basics Secondary Induced Voltage Autotransformers Power Losses Efficiency Delta/Delta Connected Transformers Delta/Wye Connected Transformers Transformer Turns Ratio Transformer kva Rating Current Flow Line Currents Part B NEC Requirements Transformer Overcurrent Protection Primary Conductor Sizing Secondary Conductor Sizing Grounding and Bonding Conclusion to Unit Practice Questions for Unit Challenge Questions for Unit viii Mike Holt s Illustrated Guide to Electrical Exam Preparation 2011 Edition

5 CHAPTER 4 MOTOR CONTROL BASICS (Journeyman and Master s Exams in Some States) UNIT 13 MOTOR CONTROL BASICS Part A Basic Motor Control Concepts Motor Control Language Motor Control Basics Reading a Motor Control Schematic Part B Motor Control Circuits Wire Control Circuits Wire Control Circuits Wire Circuit in a Wiring (Connection) Diagram Multiple Start-Stop Pushbutton Stations Reversing Three-Phase Motors Forward and Reverse Contactors Interlocking Devices Electrical Interlock for Magnetic Reversing Controls Conclusion to Unit Practice Questions for Unit Challenge Questions for Unit CHAPTER 5 NEC PRACTICE QUESTIONS (Essential for all Journeyman and Master s Exams) Practice Quizzes Practice Quiz 1 Straight Order [ ] Practice Quiz 1 Random Order [ ] Practice Quiz 2 Straight Order [ ] Practice Quiz 2 Random Order [ ] Practice Quiz 3 Straight Order [ ] Practice Quiz 3 Random Order [ ] Practice Quiz 4 Straight Order [ ] Practice Quiz 4 Random Order [ ] Practice Quiz 5 Straight Order [ ] Practice Quiz 5 Random Order [ ] Practice Quiz 6 Straight Order [ ] Practice Quiz 6 Random Order [ ] Practice Quiz 7 Straight Order [ ] Practice Quiz 7 Random Order [ ] Practice Quiz 8 Straight Order [ ] Practice Quiz 8 Random Order [ ] Practice Quiz 9 Straight Order [ ] Practice Quiz 9 Random Order [ ] Practice Quiz 10 Straight Order [ Chapter 9] Practice Quiz 10 Random Order [ Chapter 9] NEC Challenge Quizzes Challenge Quiz 1 Article 90 through Chapter Challenge Quiz 2 Article 90 through Chapter Challenge Quiz 3 Article 90 through Chapter Challenge Quiz 4 Article 90 through Chapter Challenge Quiz 5 Article 90 through Chapter Challenge Quiz 6 Article 90 through Chapter Challenge Quiz 7 Article 90 through Chapter Final NEC Exams Final Exam 1 Questions in Random Order for Article 90 through Annex C Final Exam 2 Questions in Random Order for Article 90 through Annex C ix