Top NEC Exam Topics You Must Know

Most Tested NEC Topics

Not all NEC chapters carry equal weight on licensing exams. Understanding which topics are tested most frequently can help you allocate your study time effectively.

Chapter 2: Wiring and Protection

This is consistently one of the most heavily tested chapters. Key areas include:

Branch Circuits (Article 210)

• Receptacle outlet requirements for dwelling units
• GFCI and AFCI protection requirements
• Branch circuit ratings and conductor sizing

Feeders (Article 215)

• Feeder conductor sizing
• Overcurrent protection for feeders

Services (Article 230)

• Service entrance conductor sizing
• Number of services permitted
• Service disconnecting means

Overcurrent Protection (Article 240)

• Standard ampere ratings for fuses and circuit breakers
• Conductor protection requirements
• Tap rules (240.21)

Grounding and Bonding (Article 250)

This single article is one of the most tested topics on any NEC exam. Focus on:

• Grounding electrode system
• Equipment grounding conductors
• Main bonding jumper sizing
• Grounding electrode conductor sizing

Chapter 3: Wiring Methods

Conductor Properties (Article 310)

• Table 310.16 is the most referenced table in the NEC
• Ampacity correction and adjustment factors
• Conductor application and insulation types

Cable Assemblies

• NM cable (Article 334) — dwelling unit wiring
• MC cable (Article 330) — commercial applications
• AC cable (Article 320)

Raceway Systems

• EMT (Article 358), RMC (Article 344), PVC (Article 352)
• Conduit fill calculations (Chapter 9 tables)
• Maximum number of bends between pull points

Boxes and Conduit Bodies (Article 314)

• Box fill calculations using Table 314.16(A)
• Box sizing for conductors, devices, and clamps

Chapter 4: Equipment

Motors (Articles 430-440)

• Motor circuit conductor sizing
• Motor overcurrent protection
• Motor controller requirements
• Full-load current tables

Switches and Receptacles (Articles 404-406)

• Receptacle ratings and configurations
• Switch enclosure requirements
• Tamper-resistant receptacle requirements

Chapters 5-8: Don’t Ignore These

While Chapters 1-4 are the foundation, exam questions from Chapters 5-8 can make the difference between passing and failing:

• Hazardous Locations (Article 500-516): Classification of areas, wiring methods
• Healthcare Facilities (Article 517): Essential electrical systems, patient care areas
• Swimming Pools (Article 680): Bonding requirements, clearance distances
• Solar PV Systems (Article 690): Increasingly tested as solar installations grow
• Emergency Systems (Article 700): Transfer switch requirements, wiring methods

Study Recommendations

1. Spend 60% of your time on Chapters 2-4
2. Allocate 25% to Chapters 5-8
3. Use the remaining 15% for Chapter 1 definitions and general requirements
4. Practice calculation-based questions regularly — they’re worth the same as knowledge-based questions but take more time