E2 Commercial Electrical Inspector Exam Prep

E2 COMMERCIAL ELECTRICAL INSPECTOR

6-Hour Final Review Guide — Exam Day Preparation

Use this guide the day before or morning of your exam for focused, intensive review

How to Use This 6-Hour Review

This review is designed for your final prep session right before taking the E2 exam. It focuses on the highest-value topics and most commonly tested material from the 2023 NEC (NFPA 70).

Recommended Schedule:

• Hour 1: Branch Circuit and Feeder Requirements (19% of exam — TIED HIGHEST)
• Hour 2: Wiring Methods and Distribution Systems (19% of exam — TIED HIGHEST)
• Hour 3: Services and Grounding/Bonding (17% of exam)
• Hour 4: General Use Equipment and General Requirements (22% combined)
• Hour 5: Special Occupancies, Equipment, and Systems (23% combined)
• Hour 6: Practice Questions & NEC Navigation Drills

Materials Needed:

• This review guide
• 2023 NEC (NFPA 70), tabbed and ready
• Ugly's Electrical References (any edition) — optional but helpful
• Calculator (for load calcs and conduit fill)
• Highlighter and pen
• Practice exam (for Hour 6)

Exam Facts:

• 80 questions, 3.5 hours (210 minutes) — about 2.6 minutes per question
• Open book — only the 2023 NEC is the approved reference
• Passing score: 70% (56 out of 80)
• Covers commercial and industrial installations with no limit on voltage or amperage

HOUR 1: BRANCH CIRCUIT AND FEEDER REQUIREMENTS (19% — ~15 Questions)

Why This Matters Most (Tied)

Branch circuits and feeders are 19% of your exam — roughly 15 out of 80 questions. Combined with Wiring Methods (also 19%), these two categories make up 38% of the exam. Master these two hours and you're nearly halfway to passing.

Critical Tables to Know

Tab these NOW if you haven't:

• Table 210.24(1) — Branch-Circuit Requirements Summary
• Section 210.8 — GFCI Protection Requirements
• Section 210.12 — AFCI Protection Requirements
• Table 220.42(A) — General Lighting Loads by Non-Dwelling Occupancy
• Section 240.4 — Protection of Conductors
• Section 240.6(A) — Standard Ampere Ratings of Overcurrent Devices

1.1 Branch Circuit Ratings and Sizing (210.18, 210.20)

The Basics: The rating of a branch circuit is determined by the rating of the overcurrent protective device (OCPD), NOT by the conductor ampacity (210.18).

Standard branch circuit ratings: 10, 15, 20, 30, 40, and 50 amperes (210.18). (The 2023 NEC added the 10-ampere rating; a 10A branch circuit shall not supply receptacle outlets — 210.18 Exception No. 2.)

Continuous Load Rule (210.20(A)):

Branch circuit conductors AND overcurrent devices must be sized at 125% of the continuous load plus the non-continuous load.

Formula:

```

Minimum conductor ampacity = (Continuous load × 1.25) + Non-continuous load

Minimum OCPD rating = (Continuous load × 1.25) + Non-continuous load

```

Worked Example:

A commercial lighting circuit has 16A continuous load and 4A non-continuous load.

• Minimum = (16 × 1.25) + 4 = 20 + 4 = 24 amperes
• Next standard size OCPD = 25A or 30A (per 240.6(A))
• Conductor must have ampacity ≥ 24A

Common Test Questions:

• "A branch circuit supplies 12A of continuous lighting load. What is the minimum OCPD rating?"
• 12 × 1.25 = 15A → 15A OCPD (210.20(A))
• "What determines the rating of a branch circuit — conductor ampacity or OCPD rating?"
• Answer: OCPD rating (210.18)
• "What are the standard branch circuit ratings?"
• Answer: 10, 15, 20, 30, 40, and 50 amperes (210.18)

1.2 GFCI Protection Requirements (210.8) — HEAVILY TESTED

Ground-Fault Circuit Interrupter (GFCI) protection is one of the most tested topics on the E2 exam. The 2023 NEC significantly expanded GFCI requirements.

210.8(A) — Dwelling Units:

All 125-volt through 250-volt receptacles supplied by single-phase branch circuits rated 150 volts or less to ground in:

• Bathrooms
• Garages and accessory buildings at or below grade
• Outdoors
• Crawl spaces at or below grade
• Unfinished basements
• Kitchens (serving countertop surfaces)
• Within 6 ft of sinks
• Boathouses
• Within 6 ft of bathtubs/showers
• Laundry areas
• Indoor damp/wet locations

210.8(B) — Other Than Dwelling Units (COMMERCIAL — KEY FOR E2):

All 125V through 250V receptacles supplied by single-phase branch circuits rated 150V or less to ground, 50A or less, AND all receptacles supplied by three-phase branch circuits rated 150V or less to ground, 100A or less, in:

• Bathrooms
• Kitchens
• Rooftops
• Outdoors
• Within 6 ft of sinks
• Indoor wet locations
• Locker rooms with shower facilities
• Garages and service bays
• Indoor damp/wet locations