ICC R16 Master Electrician Exam (2023 NEC) Practice Exam
Free Practice Exam
Test your knowledge with 10 questions from our pool of 20 free questions.
- 10 questions per attempt
- 30 minute time limit
- Unlimited attempts
- A new mix each time
- Instant results
Full Practice Exam
Complete exam simulation matching the real Pearson VUE test format.
- 100 questions (same as real exam)
- 300 minute time limit
- 9 topic areas covered
- 463 questions in pool
- Detailed explanations
ICC R16 Master Electrician Exam (2023 NEC) Practice Exam Guide
What's on the exam
Questions per topic, out of 100The ICC R16 Master Electrician exam is an International Code Council National Standard exam built on the 2023 NFPA 70 National Electrical Code, delivered at a Pearson VUE test center. It is open book, and the questions are four-option multiple choice with one correct answer. The content outline runs from electrical theory and Article 90 enforcement through services, feeders, branch circuits, wiring methods, equipment, motor controls, and special occupancies. Every section number you look up on test day comes from the 2023 NEC.
You get two ways to practice. The free practice exam gives you 10 questions per attempt, and you can retake it as often as you like. The full practice exam gives you 100 questions on a 5 hours clock, drawn fresh from our question bank every time you start it. Same format, same open-book habits, same pressure.
General Knowledge 12 items
Expect Ohm's law arithmetic — watts divided by volts to get amperes — plus series circuit rules where total current equals the current in any other part of the circuit. You will read distribution system color coding and the 208-volt high leg to neutral caution in Ugly's Electrical References, Common Electrical Distribution Systems. Code administration shows up too: what Article 90.2(D) does not cover, and who makes interpretations under Article 90.4(B). Termination temperature rating per NEC 2023, Section 110.14(C) and fuse let-through charts on Ugly's Electrical References, Page 57 (Component Protection) round it out.
Services and Service Equipment 16 items
This is heavy on service conductor minimums and clearances. Know 8 AWG copper or 6 AWG aluminum for overhead (NEC 230.23(B)) and underground (NEC 230.31(B)) service conductors, the 5.5 m (18 ft) clearance over public streets in NEC 230.24(B), and the 300 mm (12 in.) support rule in NEC 230.51(A). Load questions use 125 percent of continuous load per NEC 230.42(A)(1), and the 100-ampere, 3-wire minimum for a one-family dwelling in NEC 230.79(C). Grounding electrode conductor sizing under NEC 2023, Section 250.66(A) appears here as well.
Feeders 4 items
Only four items, but they are straight calculation and disconnect rules. Size feeder conductors at noncontinuous load plus 125 percent of continuous load per NEC 215.2(A)(1). Add 125 percent of the largest motor to the rest of the load, then round to the next listed overcurrent device size. Outside work brings NEC 225.6(A), where open individual copper conductors on spans up to 15 m (50 ft) are 10 AWG minimum, and NEC 225.39(C), which sets a 100-ampere, 3-wire feeder disconnect for a one-family dwelling.
Branch Circuits and Conductors 16 items
Voltage drop math on long runs shows up more than once — use the formula with NEC 2023, Chapter 9, Table 8. Ampacity work leans on NEC Table 310.16 at 30°C (86°F) ambient and the adjustment factors in NEC Table 310.15(C)(1), where 7–9 current-carrying conductors drop you to 70 percent. Conductor detail questions cover the 90°C rating of THHN in NEC Table 310.4(1), stranding at 8 AWG and larger in NEC 310.3(C), the 14 AWG copper minimum in NEC 310.3(A), and marking intervals in NEC 310.8(B)(1).
Wiring Methods and Materials 19 items
The largest topic. Working clearances come from NEC 2023, Table 110.26(A)(1) — read the condition before you read the voltage row. Protection of cables through framing is NEC 300.4(A)(1), NEC 300.4(A)(2), and NEC 300.4(D). Burial depth comes from NEC Table 300.5(A), vertical support from NEC Table 300.19(A), and free conductor length from NEC 300.14. Box work is heavy: volume allowances in NEC Table 314.16(B)(1), straight pulls at eight times trade size in NEC 314.28(A)(1), angle pulls at six times in NEC 314.28(A)(2), and sheath entry in NEC 314.17(B)(2).
Equipment and Devices 10 items
Luminaire and device limits dominate. Know the 300-watt medium base limit in NEC 410.100, the 90°C insulation requirement within 75 mm (3 in.) of a ballast or driver in NEC 410.68, and the 12 AWG copper minimum for lighting track in NEC 410.155(A). Device questions cover the 2.0 m (6 ft 7 in.) handle height in NEC 404.8(A) and the 15-ampere, 125-volt minimum receptacle rating in NEC 406.3(B). Air conditioning questions hand you MCA and MOCP and ask which one sizes the conductor.
Control Devices 3 items
Three items, all about switches and controllers on motor circuits. NEC, Section 430.110(A) sets the disconnect at not less than 115 percent of motor full-load current. NEC, Section 404.14(A) limits an ac general-use snap switch to motor loads of 80 percent of the switch rating. NEC, Section 430.102(A) requires an individual disconnecting means in sight from each controller — one common disconnect ahead of several controllers does not comply. NEC, Section 430.83(C) allows a general-use switch rated twice the motor full-load current.
Motors and Generators 8 items
Conductor sizing for a single continuous-duty motor is 125 percent of full-load current per NEC 430.22, and the full-load current itself comes off NEC Table 430.248 for single-phase work — not off the nameplate. Generator questions use Article 445.13(A) for 115 percent of nameplate current to the first distribution device. Three-phase power math appears too: kilowatts equal volts times amps times power factor times 1.73, divided by 1000, per Ugly's Electrical References, Book Page 22.
Special Occupancies, Equipment, and Conditions 12 items
Hazardous locations and health care carry this topic. Know the 450 mm (18 in.) seal distance in Article 501.15(A)(1), the classified space around outdoor dispensers in Table 514.3(B)(1), and the 6 m (20 ft) to 30 m (100 ft) emergency shutoff placement in Article 514.11(A). Commercial garage lighting height is Article 511.7(B)(1). Health care items cover branch circuits at patient bed locations and the protected wiring methods for life safety and critical branches in Article 517.31(C)(3). Mobile homes bring Article 550.11(A).
Sample 1 — Wiring Methods and Materials
Question: A 480V switchboard has exposed live parts front and rear. What is minimum working clearance required?
- A. 3 ft
- B. 4 ft
- C. 5 ft
- D. 6 ft
Correct Answer: B
Exposed live parts on both sides of the working space puts you in Condition 3. Go to NEC 2023, Table 110.26(A)(1), find the 151–600 volts-to-ground row, then read across to the Condition 3 column: 4 ft. The trap is reading Condition 1 or Condition 2 because you only registered the voltage. Identify the condition first — what is on each side of the space — then pick the voltage row.
Sample 2 — Services and Service Equipment
Question: What is maximum required grounding electrode conductor size to a driven ground rod?
- A. 4 AWG
- B. 2 AWG
- C. 1/0 AWG
- D. 6 AWG
Correct Answer: D
NEC 2023, Section 250.66(A) caps the grounding electrode conductor run to a driven rod electrode at 6 AWG copper. It does not matter how large the service conductors are — the rod connection never has to be bigger than that. Candidates who size the whole GEC off the service conductor table pick 4 AWG or larger and miss it. Read the question for which electrode is involved before you open the table.
Sample 3 — Branch Circuits and Conductors
Question: A feeder is 350 ft long supplying 100A at 240V single-phase. Conductors are 3/0 copper. What is approximate voltage drop?
- A. 3.5V
- B. 5.0V
- C. 6.5V
- D. 8.0V
Correct Answer: B
Run the single-phase voltage drop formula using circular mils from NEC 2023, Chapter 9, Table 8 (voltage drop formula); see also NEC 210.19 Informational Note. With 3/0 copper over 350 feet at 100 amperes on a 240-volt single-phase circuit, the drop lands near 2 percent of 240 volts, which is about 5 volts. The wrong options come from forgetting to double the one-way length, or from using the wrong circular mil area. Set the formula up the same way every time.
Your first full practice attempt is a diagnostic, nothing more. Take it cold, on the clock, with your books, and let the number tell you where you actually stand against 75% correct. Do not retake it the same day to chase a better number — that just measures memory of the questions.
Work the topic breakdown instead of the total. The score report shows you which outline topics you dropped points in, and that is your study list for the week. Fix the topic, then retest.
Weight your effort by item count. Wiring Methods and Materials is 19 items, Services and Service Equipment and Branch Circuits and Conductors are 16 each, and General Knowledge and Special Occupancies are 12 each. Those five carry most of the exam. Control Devices is 3 items and Feeders is 4 — worth knowing, not worth a week.
Watch how you scored on lookups versus calculations. If you are losing calculation items, that is a formula drill problem. If you are losing lookup items, that is a book-familiarity problem, and the answer is more time in the tables, not more practice questions.
Reading the conductor instead of the termination. In General Knowledge, a 90°C conductor on a 75°C terminal is limited to the 75°C column. NEC 2023, Section 110.14(C) sets ampacity by the lowest-rated termination, conductor or device in the path. The 90°C column is still your starting point for correction and adjustment factors, but the final value cannot exceed the 75°C ampacity. The distractor is always the 90°C number.
Skipping the condition in the working clearance table. Wiring Methods and Materials questions describe the space — live parts front and rear, grounded surface opposite, and so on — because that description picks your column in NEC 2023, Table 110.26(A)(1). Read the description, name the condition, then read the voltage row.
Mixing up the 125 percent rules. Feeders use noncontinuous load plus 125 percent of continuous load per NEC 215.2(A)(1). Services use the same structure per NEC 230.42(A)(1). Motor conductors use 125 percent of full-load current per NEC 430.22, but the motor disconnect uses 115 percent per NEC, Section 430.110(A). Know which percentage belongs to which piece of the circuit.
Grabbing a common disconnect for multiple controllers. In Control Devices, NEC, Section 430.102(A) wants an individual disconnecting means for each motor controller, in sight from that controller. One disconnect ahead of three controllers, or a disconnect back at the panelboard, is the offered wrong answer.
Using the nameplate instead of the table. Motors and Generators questions give you horsepower and voltage, and the answer comes off NEC Table 430.248 for single-phase full-load current. For air conditioning equipment in Equipment and Devices, size conductors from MCA, not MOCP — the overcurrent number is there to pull you off.
Burning time on lookups. You have 5 hours for 100 questions, which is about 3 minutes per question. That is enough time to open a book, but only if you know where you are going. Speed comes from practice, so run the full practice exam on the clock and stop hunting for tables you should already know by heart.
| Questions | 100 questions |
| Time limit | 5 hours |
| Passing score | 75% correct |
| Books in the exam room | Open book |
| Exam fee | $120 |
- Results for examinations taken electronically are available immediately after the examination is completed.
- You must wait 10 days before retaking a failed exam.
Source: National Contractor/Trades Examination Information Bulletin, PUBLISHED June 30, 2026; ICC Exam Catalog, checked September 27, 2026. Check the bulletin before test day: fees and rules can change.