ICC R16 Master Electrician Exam (2023 NEC): Complete Study Guide
The ICC R16 master electrician exam is the International Code Council National Standard exam built on the 2023 NFPA 70 National Electrical Code. You take it at a Pearson VUE test center. It's written for electricians going after a master-level credential, and it's open book — the code is on the table with you.
One thing to be clear about up front: ICC is not a licensing agency. Passing this exam does not hand you a license. A city, county, or state decides whether it accepts ICC results toward its own license, so check with the jurisdiction you want to work in before and after you test.
This guide walks you through the exam format, every scored topic and how many items it carries, real sample questions from our verified question bank, the two references the exam is built on, and how to study for a code exam you're allowed to look things up on.
ICC R16 Master Electrician Exam (2023 NEC) at a Glance
Here are the numbers and rules you need before you register.
| Questions | 100 questions |
| Time limit | 5 hours |
| Passing score | 75% correct |
| Books in the exam room | Open book |
| Exam fee | $120 |
On exam day
- Questions are four-option multiple choice with one correct answer.
- Any copyrighted, bound book may be used at a test site. Exam questions will only come from the listed approved references, and exam appeals may only be based on the listed approved references.
References you may bring
- National Electrical Code (NEC) (2023)
- Ugly's Electrical Reference (any edition)
Scheduling, changes and retakes
- Exams are scheduled through PearsonVUE at www.pearsonvue.com/ICC, where candidates can create an account, schedule an exam, locate a test center, purchase vouchers and request accommodations.
- Results for examinations taken electronically are available immediately after the examination is completed.
- You must wait 10 days before retaking a failed exam.
- After passing, contact the jurisdiction in which you wish to be licensed for any other requirements, because ICC is not a licensing agency.
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.
What the Exam Covers
The exam has 100 questions, each four-option multiple choice with one correct answer. Here's how they break down by topic, heaviest first.
Wiring Methods and Materials — 19 items (19%)
The biggest block on the test. Expect raceway installs, underground wiring, boxes and enclosures, panelboards and switchboards, clearance and guarding, flexible cords, and the full list of cable methods — NM, MC, AC, MI, SE, UF, TC, ITC, FC, FCC, IGS and Type P. Conductor fill and conduit sizing math shows up here too.
Verified questions in this area ask things like minimum working clearance at a 480V switchboard with exposed live parts front and rear (NEC 2023, Table 110.26(A)(1)), how far the edge of a bored hole must sit from the edge of a wood member (NEC 300.4(A)(1)), minimum cover for direct-buried cable (NEC Table 300.5(A)), box fill volume per 14 AWG conductor (NEC Table 314.16(B)(1)), and straight pull box length (NEC 314.28(A)(1)). Know your tables cold here.
Services and Service Equipment — 16 items (16%)
Service load calculations, service conductors and equipment, transformers, system grounding and bonding, temporary service wiring, fault current, and overhead and underground clearances.
Real questions cover the minimum service disconnect rating for a one-family dwelling (NEC 230.79(C)), overhead clearance over public streets and alleys (NEC 230.24(B)), minimum ampacity for service-entrance conductors serving continuous loads (NEC 230.42(A)(1)), minimum overhead and underground conductor sizes (NEC 230.23(B) and NEC 230.31(B)), grounding electrode conductor size to a driven rod (NEC 2023, Section 250.66(A)), and service-entrance cable support spacing (NEC 230.51(A)).
Branch Circuits and Conductors — 16 items (16%)
Branch circuit calculations, overcurrent protection, required outlets, GFCI and AFCI protection, equipment grounding, voltage drop single- and three-phase, ampacity correction and adjustment, and insulation types.
Questions hit the adjustment factor for 7–9 current-carrying conductors (NEC Table 310.15(C)(1)), the ambient temperature Table 310.16 is based on (NEC 310.16), when conductors in raceway must be stranded (NEC 310.3(C)), THHN maximum operating temperature in dry and damp locations (NEC Table 310.4(1)), AWG marking intervals (NEC 310.8(B)(1)), minimum conductor size for general wiring (NEC 310.3(A)), and conductor color coding in a 120/240-volt three-wire system.
General Knowledge — 12 items (12%)
Electrical theory and general load calculations, code definitions, plan reading, AC circuit concepts — impedance, reactance, inductance, capacitance — power factor and kVA, Kirchhoff's laws, distribution systems and color coding, and Article 90 scope and enforcement.
Verified items ask which ampacity column applies when a 90°C conductor lands on a 75°C termination (NEC 2023, Section 110.14(C)), what installations the NEC does not cover (Article 90.2(D)), who makes interpretations of the rules (Article 90.4(B)), Ohm's law current draw problems, series circuit current relationships, and the voltage between the high leg and neutral on a 120/240 delta system.
Special Occupancies, Equipment, and Conditions — 12 items (12%)
Hazardous location classification, swimming pools, mobile home and RV parks, data processing, emergency systems, fire alarm and signaling, and health care.
Expect branch circuits at patient bed locations, fixed lighting height in commercial garages (Article 511.7(B)(1)), emergency shutoff separation at motor fuel dispensing facilities (Article 514.11(A)), life safety and critical branch wiring methods (Article 517.31(C)(3)), mobile home panelboard rating (Article 550.11(A)), conduit seal distance in Class I, Division 1 (Article 501.15(A)(1)), and the Class I, Division 2 boundary around an outdoor dispenser (Table 514.3(B)(1)).
Equipment and Devices — 10 items (10%)
Luminaires, receptacles, switches, appliances, heating and cooling equipment, fixture wire, and recessed luminaire clearances and Type IC requirements.
Questions include maximum wattage for a medium-base incandescent lamp (NEC 410.100), insulation temperature rating for conductors within 75 mm (3 in.) of a ballast or LED driver (NEC 410.68), minimum track conductor size (NEC 410.155(A)), switch handle mounting height (NEC 404.8(A)), and minimum receptacle ratings (NEC 406.3(B)).
Motors and Generators — 8 items (8%)
Motor branch-circuit conductor sizing, overload protection, short-circuit and ground-fault device ratings, disconnects, controllers, and generators.
Verified questions cover conductor ampacity for a continuous-duty motor (NEC 430.22 and NEC 2023, Section 430.22(A)), generator conductor ampacity to the first distribution device (Article 445.13(A)), three-phase kW from measured current and power factor (Ugly's Electrical References, Book Page 22), and full-load current lookups (NEC Table 430.248).
Feeders — 4 items (4%)
Feeder load calculations, equipment grounding, minimum ampacity, overcurrent protection, ground-fault protection, conductor identification, surge protection, and outside feeder disconnects. Sample items ask the continuous-load percentage for feeder sizing (NEC 215.2(A)(1)), minimum open conductor size for spans up to 15 m (50 ft) (NEC 225.6(A)), and the minimum feeder disconnect rating for a one-family dwelling (NEC 225.39(C)).
Control Devices — 3 items (3%)
Switches, disconnects, controllers, motor control circuits, overload devices, motor control centers, stop-start and jogging circuits, and industrial control panels. Questions cover disconnect current rating as a percentage of motor FLC (NEC, Section 430.110(A)), snap switch motor load limits (NEC, Section 404.14(A)), where controller disconnects must be located (NEC, Section 430.102(A)), and general-use switch ratings as motor controllers (NEC, Section 430.83(C)).
Sample Questions
Try these before you look anything up, then check yourself on the free practice exam: 10 questions per attempt.
1. You are installing PVC conduit on an exterior wall of a commercial building where temperature swings of 80°F are expected. According to the NEC, when must expansion fittings be provided for PVC conduit?
A. When the expected length change is 1/8 inch or greater
B. When the expected length change is 1/4 inch or greater
C. When the expected length change is 1/2 inch or greater
D. When the total conduit run exceeds 50 feet
Tests whether you can locate the NEC's PVC expansion fitting requirements.
2. At what service size is GFPE required for solidly grounded wye systems 150V to ground?
A. 600A
B. 800A
C. 1000A
D. 1200A
Tests ground-fault protection of equipment thresholds for services.
3. A 400 ft run supplies 100A, 240V single-phase, using 3/0 CU THHN. What is approximate voltage drop?
A. 5V
B. 6.4V
C. 8.0V
D. 9.2V
Tests single-phase voltage drop calculation using conductor resistance from Chapter 9, Table 8.
4. When using a fuse let-through chart, the apparent prospective RMS symmetrical let-through current is used to evaluate which physical effect on downstream components?
A. Heating effect on conductors and equipment
B. Arc flash boundary distance
C. Mechanical stress on bus bars
D. Insulation breakdown voltage
Tests whether you can read a component protection let-through chart and tell thermal effects from mechanical ones.
What Types of Questions to Expect
Every question is four-option multiple choice with one correct answer. There's no essay and no fill-in-the-blank.
Three flavors show up again and again:
Straight lookups. A single number sits in a code section or table. Minimum cover. Minimum conductor size. Clearance height. If you know where to look, these take seconds.
Table reads with a twist. You find the table, then apply a condition to it — Condition 3 working clearance, a 70 percent adjustment factor, a 75°C termination on a 90°C conductor. The table alone isn't the answer.
Calculations. Voltage drop, load calculations, motor conductor sizing, box fill, kW from measured amps and power factor, Ohm's law. Some require a table lookup first, then math.
Scenario-style stems are common — a garage feeder, a 50 hp motor, an HVAC unit on a roof. Read past the story and find the actual question.
Study Materials
The ICC National Standard master electrician exam is built on two references and nothing else. Questions come only from these, and appeals are decided only against these.
- National Electrical Code 2023 — required. This is the book the entire exam is written from. Every section number, table and calculation on the test traces back to the 2023 edition. ICC also offers this same exam on the 2017 and 2020 NEC under different exam codes, so make sure you have the 2023.
- Ugly's Electrical References 2023 — required. Any edition is listed as approved. This is where the formulas, distribution system diagrams, Ohm's law wheel, and component protection charts live. Several verified questions cite Ugly's directly, not the NEC.
The exam is open book. That's the whole point of owning these two and knowing them.
Study Tips
Weight your study time the way the exam weights its items. Wiring Methods, Services, and Branch Circuits together make up just over half the test. If your speed is strong in those three areas, you're in good shape before you touch the smaller topics.
Open book does not mean easy. It means the exam assumes you'll look things up — and it's timed accordingly. You need to know where a rule lives, not memorize the number. Work through your NEC by article until you can land on Chapter 3 wiring methods, Article 230 services, and Chapter 9 tables without hunting.
Practice the math with the book open, on paper, the way you'll do it on test day. Voltage drop, motor conductor sizing, box fill, and load calculations all reward repetition. Get the formula path automatic so the only work left is the lookup.
Pace yourself at about 3 minutes per question. Answer every lookup you know cold on the first pass. Flag the long calculations and come back. Never leave a question blank.
Take a full-length ICC master electrician practice test 2023 NEC under real conditions — 100 questions, timed, open book. That's how you find out whether your lookup routine actually works under pressure.
Aim comfortably above 75% correct on practice runs. A cushion on practice means a cushion on test day.
Next Steps
Get your 2023 NEC and Ugly's and start drilling the heavy topics.
Start with the free practice exam to see where you stand. Read the official bulletin for the exam-day details. Register for the Pearson VUE ICC master electrician exam at Pearson VUE.
Then check with the jurisdiction where you want to be licensed. ICC credentialing information is at iccsafe.org, but the local authority is the one that decides what your result is worth.