Table of Contents. CHAPTER 1 ElECTRiCAl THEoRY Mike Holt enterprises, inc neC.Code ( )

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1 CHAPTER 1 ElECTRiCAl THEoRY... 1 UniT 1 electrician s MaTH and BasiC electrical formulas... 3 Introduction to Unit Part A Electrician s Math... 3 Introduction 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...10 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...18 Conclusion to Unit Unit 1 Practice Questions...21 Unit 1 Challenge Questions...26 UniT 2 electrical CiRCUiTs...28 Introduction to Unit 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...34 Part B Parallel Circuits...34 Introduction Practical Uses of the Parallel Circuit Understanding Parallel Calculations Circuit Resistance Parallel Circuit Notes Parallel-Connected Power Supplies...40 Part C Series-Parallel Circuits...40 Introduction Review of Series and Parallel Circuits Working With Series-Parallel Circuits Voltage...42 Part D Multiwire Branch Circuits...42 Introduction Neutral Conductor Grounded Conductor Current Flow on the Neutral Conductor Balanced Systems Unbalanced Current Multiwire Branch Circuits Dangers of Multiwire Branch Circuits NEC Requirements...48 Conclusion to Unit Unit 2 Practice Questions...50 Unit 2 Challenge Questions...55 UniT 3 UndeRsTanding alternating CURRenT...59 Introduction to Unit Part A Understanding Alternating Current...59 Introduction Current Flow Why Alternating Current is Used How Alternating Current is Produced AC Generator Waveform Sine Wave Frequency Phase Degrees Lead or Lag Values of Alternating Current...64 Part B Capacitance...64 Introduction Charged Capacitor Electrical Field Discharging a Capacitor...66 Mike Holt enterprises, inc neC.Code ( ) v

2 3.15 Determining Capacitance Uses of Capacitors Phase Relationship...67 Part C Induction...68 Introduction Self-Induction Induced Voltage and Applied Current Conductor AC Resistance Conductor Shape Magnetic Cores Self-Induced and Applied Voltage Inductive Reactance Phase Relationship Uses of Induction...73 Part D Power Factor...73 Introduction Apparent Power (Volt-Amperes) True Power (Watts) Power Factor Unity Power Factor Power Factor Formulas Cost of True Power Effects of Power Factor...77 Part E Efficiency...78 Introduction Efficiency Formulas...79 Conclusion to Unit Unit 3 Practice Questions...81 Unit 3 Challenge Questions...88 Unit 4 Motors and Transformers...92 Introduction to Unit Part A Motor Basics...92 Introduction 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 Direct-Current Motor Principles Direct-Current Motor Types Reversing the Rotation of a DC Motor AC Induction Motor Alternating-Current Motor Types Reversing the Rotation of an AC Motor...99 Part B Transformers...99 Introduction Transformer Basics Secondary Induced Voltage Efficiency Transformer Turns Ratio Autotransformers Power Losses Transformer kva Rating Current Flow Current Rating Conclusion to Unit Unit 4 Practice Questions Unit 4 Challenge Questions CHAPTER 2 NEC CalcuLations Unit 5 Raceway and Box Calculations Introduction to Unit Part A Raceway Fill Introduction Understanding the NEC, Chapter 9 Tables Raceway Calculations Wireways Tips for Raceway Calculations Part B Outlet Box Fill Calculations [314.16] Introduction Sizing Box Conductors All the Same Size [Table (A)] Conductor Equivalents Outlet Box Sizing [314.16(B)] Part C Pull Boxes, Junction Boxes, and Conduit Bodies Introduction Pull/Junction Box Sizing Requirements Pull/Junction Box Sizing Tips Pull Box Examples Summary Conclusion to Unit Unit 5 Practice Questions Unit 5 Challenge Questions Unit 6 Conductor Sizing and Protection Calculations Introduction to Unit Part A General Conductor Requirements Introduction Conductor Insulation [Table ] Conductor Sizing [110.6] Smallest Conductor Size [310.5] Conductor Size Terminal Temperature Rating [110.14(C)] Conductors in Parallel NEC Requirements for Conductors in Parallel [310.4] Overcurrent Protection [Article 240] Overcurrent Protection of Conductors General Requirements [240.4] Overcurrent Protection of Conductors Specific Requirements vi Mike Holt s Illustrated Guide to NEC Exam Preparation

3 Part B Conductor Ampacity Introduction Conductor Ampacity Ambient Temperature Correction Factor [Table ] Conductor Bundling Ampacity Adjustment Factor [Table (B)(2)(a)] Ambient and Conductor Bundling Adjustment Current-Carrying Conductors Conductor Sizing Summary Conclusion to Unit Unit 6 Practice Questions Unit 6 Challenge Questions Unit 7 Motor and Air-Conditioning Calculations Introduction to Unit 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 [430.61] Motor VA Calculations Part B Air-Conditioning Calculations Scope of Article Other Articles Short-Circuit and Ground-Fault Protection Conductor Sizing for Single Motor-Compressor Conclusion to Unit Unit 7 Practice Questions Unit 7 Challenge Questions Unit 8 Voltage-Drop Calculations Introduction to Unit PART A CONDUCTOR RESISTANCE CALCULATIONS Introduction Conductor Resistance Conductor Resistance Direct-Current Circuits [Chapter 9, Table 8] Conductor Resistance Alternating-Current Circuits Alternating-Current Resistance AC Resistance as Compared to DC Resistance PART B Voltage-Drop Considerations Introduction 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 Fire Pump Motor Circuits Sizing Conductors with Loads at Different Distances Conclusion to Unit Unit 8 Practice Questions Unit 8 Challenge questions Unit 9 Dwelling Unit Calculations Introduction to Unit Part A General Requirements Introduction General Requirements Voltages [220.5(A)] Fraction of an Ampere [220.5(B)] Small-Appliance Circuits [210.11(C)(1)] Cooking Equipment Branch Circuit [Table , Note 4] Laundry Circuit [210.11(C)(2)] Lighting and Receptacles PART B Standard Method Feeder/Service Load Calculations Introduction Dwelling Unit Feeder/Service Load Calculations (Article 220, Part III) Dwelling Unit Example Part C Optional Method Feeder/Service Load Calculations Introduction 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 Unit 9 Practice Questions Unit 9 Challenge Questions CHAPTER 3 Advanced NEC Calculations Unit 10 Multifamily Dwelling Calculations Introduction to Unit Multifamily Dwelling Calculations General Part A Standard Method Feeder/Service Load Calculations Introduction Multifamily Dwelling Unit Calculation Examples Standard Method Multifamily Dwelling Calculations Standard Method Example Mike Holt Enterprises, Inc NEC.CODE ( ) vii

4 Part B Optional Method Feeder/Service Load Calculations Introduction Multifamily Dwelling Unit Calculations [220.84] Optional Method Multifamily Optional Method Example 1 [220.84] Multifamily Optional Method Example 2 [220.84] Conclusion to Unit 10 Multifamily Dwelling Calculations Unit 10 Practice Questions Unit 10 Challenge Questions Unit 11 Commercial Calculations Introduction to Unit Part A General Introduction General Requirements Conductor Ampacity [Article 100] Conductor Overcurrent Protection [240.4] Voltages [220.5(A)] Rounding an Ampere [220.5(B)] Lighting Demand Factors [Tables and ] Lighting Without Demand Factors [215.2(A)(1), (A)(1), and Table ] Lighting Miscellaneous Multioutlet Receptacle Assembly [220.14(H)] Receptacle VA Load Banks and Offices General Lighting and Receptacles [220.14(K)] Sign Circuit [220.14(F) and 600.5] Part B Examples Bank/Office Building Example Marina [555.12] Mobile/Manufactured Home Park [550.31] Recreational Vehicle Park [551.73] Part C Optional Method Feeder/Service Load Calculations Introduction New Restaurant Optional Method [220.88] Part D Welders Introduction Arc Welders Resistance Welders Light Industrial Calculation Conclusion to Unit Unit 11 Practice Questions Unit 11 Challenge Questions Unit 12 Transformer calculations Introduction to Unit Part A General Introduction 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 Available Short-Circuit Current Conclusion to Unit Unit 12 Practice Questions Unit 12 Challenge Questions Chapter 4 NEC Practice Quizzes, Challenge Quizzes, and Final NEC Exams Practice Quizzes Unit 1 Practice Questions in Straight Order Article 90.1 through Unit 1 Practice Questions in Random Order Article 100 through Unit 2 Practice Questions in Straight Order Article through Unit 2 Practice Questions in Random Order Article 90.2 through Unit 3 Practice Questions in Straight Order Article through Unit 3 Practice Questions in Random Order Article 90.2 through Unit 4 Practice Questions in Straight Order Article 100 through Unit 4 Practice Questions in Random Order Article 90.1 through Unit 5 Practice Questions in Straight Order Article through Unit 5 Practice Questions in Random Order Article 90.4 through Unit 6 Practice Questions in Straight Order Article through Unit 6 Practice Questions in Random Order Article 90.2 through Unit 7 Practice Questions in Straight Order Article through viii Mike Holt s Illustrated Guide to NEC Exam Preparation

5 Unit 7 Practice Questions in Random Order Article 90.2 through Unit 8 Practice Questions in Straight Order Article through Unit 8 Practice Questions in Random Order Article 90.2 through Unit 9 Practice Questions in Straight Order Article through Unit 9 Practice Questions in Random Order Article 90.3 through Unit 10 Practice Questions in Straight Order Article through Chapter Unit 10 Practice Questions in Random Order Article 90.3 through Annex C 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 Exams Final Exam 1 Practice Questions in Random Order Article 90 through Annex C Final Exam 2 Practice Questions in Random Order Article 90 through Annex C Mike Holt Enterprises, Inc NEC.CODE ( ) ix