South Carolina Residential Electrical

South Carolina Residential Electrical Exam: What You Need to Know to Pass

You've put in the hours on the job. Now you need to get licensed. The South Carolina Residential Electrical exam stands between you and your contractor's license — and knowing exactly what's on it makes a real difference. This exam covers 60 questions across nine topic areas, from NEC code calculations to safety requirements, and you'll need to answer at least 45 of them correctly to pass. This guide breaks down every part of the exam: what's on it, how it's structured, which books you need, and how to prepare smart.

Exam Overview

The South Carolina Residential Electrical exam is a 60-question, open-book test administered by PSI. You have 180 minutes (3 hours) to complete it. The passing score is 74%, which works out to 45 correct answers out of 60.

SC applicants also have the option to take the NASCLA Accredited Trade Examination for Residential Electrical Contractors instead. That version has 100 questions and a 270-minute time limit. If you go the NASCLA route, you need 70 out of 100 correct to pass.

The exam is given on a computer at PSI testing centers. You bring your approved reference books, you work through the questions, and you manage your own time. There are no trick formats — it's multiple choice, four options per question.

Note: You also need to pass a separate Business Management and Law for Residential Builders Examination (50 questions, 68% passing score, 120-minute time limit) in addition to your trade exam. Both are required for licensure.

For full exam details, check the official exam bulletin or the state licensing website.

Topics Covered on the South Carolina Residential Electrical Exam

Here's how the 60 exam questions break down by topic area:

• Services, Feeders, and Branch Circuits — 15 questions (25% of the exam). This is the biggest topic. Expect questions on installing services, feeders, branch circuits, temporary installations, and motors used in dwellings. Put serious time here.
• General Electrical Knowledge — 13 questions. Ohm's law, series and parallel circuits, AC theory, voltage drop, power calculations, and troubleshooting. These are foundational — if you're shaky here, everything else gets harder.
• Grounding and Bonding — 6 questions. General requirements, grounding electrode conductor sizing, and equipment grounding conductor sizing. Use the NEC tables and know them cold.
• Overcurrent Protection — 5 questions. NEC requirements for OCPD selection and panelboard wiring space fill.
• Conductors and Cables — 5 questions. Underground installations, vertical runs, conductor selection, Type AC armored cable, and Type MC metal-clad cable.
• Raceways and Boxes — 4 questions. General requirements for both, plus RMC, EMT, and IMC installations.
• Lighting — 4 questions. Fixture installation, grounding, wiring, and fluorescent fixtures.
• Specialty (pools/spas, generators, garages, wheelchair lifts) — 4 questions. Pool and spa wiring, bonding and grounding for aquatic equipment, generators, and wheelchair lifts.
• Safety — 4 questions. PPE responsibilities, emergency action plans, safety training, and first aid requirements.

Spend the most time on Services, Feeders, and Branch Circuits and General Electrical Knowledge — those two topics alone account for 28 of your 60 questions.

Sample Questions

Here are five sample questions pulled from the exam topic areas. Work through them — and keep in mind, the answers are NOT shown here. Try our free practice exam to check your knowledge.

Question 1 — Services, Feeders, and Branch Circuits (Medium)

During temporary wiring installations on a construction site, which of the following statements about receptacles is correct?

• A) Receptacles may be installed on the same branch circuit that supplies temporary lighting
• B) Receptacles are not required to be of the grounding type for temporary installations
• C) Receptacles on construction sites shall not be installed on any branch circuit that supplies temporary lighting
• D) Only 20-ampere receptacles are permitted for temporary construction site use

This question tests your knowledge of NEC rules for temporary wiring — specifically how branch circuits for lighting and receptacles interact on a job site.

Question 2 — Specialty: Generators (Hard)

You are a residential electrician installing a permanently mounted 20 kW standby generator at a single-family home. The generator uses a 4-pole transfer switch that disconnects the grounded conductor (neutral) from the utility supply when the generator is operating. Because the neutral is switched, the generator is considered a separately derived system. Where must the system bonding jumper for this separately derived system be connected?

• A) To the grounding electrode only, at a point remote from the generator
• B) At any single point from the source to the first system disconnecting means or overcurrent device
• C) At both the source and the first disconnecting means simultaneously to ensure redundancy
• D) To the metal water piping system inside the dwelling at any convenient location

This one is code-specific and technical. It tests whether you know the NEC bonding requirements for separately derived systems — the kind of detail that trips up people who've only skimmed the grounding sections.

Question 3 — Overcurrent Protection (Medium)

You are a residential electrician installing a panelboard in a new single-family home. The panelboard enclosure contains feed-through conductors spliced and tapping off to other enclosures. What is the maximum percentage of the cross-sectional area of the wiring space that all conductors, splices, and taps installed at any cross section may occupy?

• A) 53 percent
• B) 40 percent
• C) 75 percent
• D) 60 percent

Know your NEC wiring space fill percentages. This is a straightforward code lookup.

Question 4 — Grounding and Bonding (Medium)

When the grounding electrode conductor connects solely to a rod, pipe, or plate electrode and does not extend to other types of electrodes, the grounding electrode conductor is not required to be larger than which of the following?

• A) 8 AWG copper
• B) 6 AWG copper
• C) 2 AWG copper
• D) 4 AWG copper

This is a direct NEC table question. Get comfortable with electrode conductor sizing tables before test day.

Question 5 — Conductors and Cables (Medium)

What is the minimum bending radius for interlocked-type armor or corrugated sheath Type MC cable?

• A) Five times the external diameter of the metallic sheath
• B) Ten times the external diameter of the metallic sheath
• C) Seven times the external diameter of the metallic sheath
• D) Twelve times the external diameter of the metallic sheath

Installation rules for Type MC cable come up on the exam. Know the bending radius requirements.

What Types of Questions to Expect

Here's a breakdown of what you'll actually be working through in each topic area, along with how many practice questions we offer to help you drill each one.

• General Electrical Knowledge (67 practice questions): Ohm's law calculations, series and parallel circuit analysis, AC theory application, power calculations, voltage drop formulas for branch circuits and feeders, and troubleshooting scenarios.
• Services, Feeders, and Branch Circuits (150 practice questions): This is the largest section of our practice bank for good reason. Questions cover service installation requirements, feeder sizing, branch circuit rules, temporary wiring setups on construction sites, and motor installations in residential settings.
• Overcurrent Protection (22 practice questions): NEC rules for OCPD sizing and placement, panelboard wiring space fill calculations, and breaker and fuse application requirements.
• Grounding and Bonding (81 practice questions): General grounding requirements, grounding electrode conductor sizing from NEC tables, equipment grounding conductor sizing, and bonding requirements for services and equipment.
• Conductors and Cables (64 practice questions): Underground conductor installation rules, vertical installation requirements, conductor selection based on ampacity tables, and installation requirements specific to Type AC and Type MC cable.
• Raceways and Boxes (60 practice questions): General raceway fill and installation rules, box fill calculations, and installation specifics for RMC, EMT, and IMC.
• Lighting (15 practice questions): Fixture installation and grounding rules, fixture wiring methods, construction requirements, and fluorescent fixture specifics.
• Specialty (9 practice questions): Wiring and bonding requirements for pools, spas, and hot tubs; generator installation rules for separately derived systems; and wheelchair lift installation requirements.
• Safety (13 practice questions): OSHA-based questions on PPE responsibilities, emergency action plan requirements, safety training obligations, and first aid kit requirements per 29 CFR 1926.

In total, our full practice bank has 481 questions across all nine topic areas.

Required Study Materials

This is an open-book exam, so you need to own the right books and know them well enough to find answers fast. These are the approved references:

Required Books:

• NEC 2017 — The National Electrical Code 2017 edition is the core reference for this exam. Nearly everything on Services, Feeders, Grounding, Overcurrent Protection, and Conductors ties back to this book. Tab it thoroughly.
• OSHA 29 CFR 1926 — Required for the Safety section. Know the construction industry standards, especially PPE, emergency action plans, and first aid requirements.
• Ugly's Electrical References 2020 — A compact, practical field reference with conductor ampacity tables, conduit fill data, and other quick lookups. Useful on the exam for fast reference.

Recommended Supplies:

Open-book means nothing if you can't find the right page quickly. These two tools are worth every penny:

• Sharpie Highlighters — Bright fluorescent ink, a chisel tip that's good for both highlighting and writing, and 12 highlighters in assorted colors. Color-code by topic area in your NEC.
• Redi-Tag Permanent Colored Tabs — 100 permanent adhesive index tabs in five colors. Temporary tabs like Post-It notes are not allowed at PSI testing centers, so these permanent tabs are exactly what the bulletin permits. Tab every article and table you'll need to reference.

Your books need to be ready before exam day. Don't walk in with a brand-new, untabbed codebook.

Study Tips

Focus on the right topics first. Services, Feeders, and Branch Circuits (15 questions) and General Electrical Knowledge (13 questions) account for nearly half the exam. Master those before going deep on Specialty or Lighting.

Practice under real conditions. Untimed PDF study guides are fine for learning, but they don't prepare you for 180 minutes on a clock. Take timed practice tests. Our full practice exam matches the real exam — 60 questions, same time limit, same topic breakdown. Every attempt draws from a large question pool so you're not just memorizing a fixed set.

Start free, then go deep. The free practice exam gives you 10 questions with no account required — good for getting a feel for the format. For real preparation, the full practice exam gives you a detailed score breakdown by topic so you know exactly where to spend more time.

Tab your books before exam day. You won't have time to flip through unprepared books during the test. Tab every key NEC article and table in advance using permanent tabs.

Manage nerves on test day. A little anxiety is normal. If you get stuck on a question, take a few slow breaths and move on — come back to it. If the test center allows a short break, use it. Just remember the clock keeps running.

Hit your target score consistently in practice before you sit the real exam. You need 74% to pass. Practice until you're clearing that number with room to spare.

Frequently Asked Questions

How many questions are on the South Carolina Residential Electrical exam and how long do I have?
The exam has 60 scored questions and a 180-minute (3-hour) time limit. SC applicants also have the option to take the NASCLA Accredited Trade Examination for Residential Electrical Contractors, which has 100 questions and a 270-minute time limit.

What is the passing score?
You need to answer 45 out of 60 questions correctly (74%) to pass the state-specific exam. For the NASCLA version, you need 70 out of 100 correct.

(Note: The official exam bulletin should be your final word on pass/fail thresholds — confirm the exact figure there before exam day.)

How much does the exam cost?
The PSI exam fee for both portions of the Residential Examination is $90. One portion only is $75. If you take the NASCLA Residential Electrical exam instead, the fee is $116. Registration fees are non-refundable and non-transferable.

Is the exam open book?
Yes. You can bring approved reference books. They may be highlighted, underlined, and permanently tabbed, but no writing in the margins and no loose or attached additional papers. Post-It notes and other temporary tabs are not allowed — use permanent adhesive tabs.

What reference books are approved?
Approved references include the NFPA 70 NEC (2017 edition), the International Residential Code for One- and Two-Family Dwellings (2018 edition or SC version), Ugly's Electrical References (2017), and OSHA 29 CFR Part 1926 with latest amendments.

Do I need to pass any other exams?
Yes. All candidates must also pass the Business Management and Law for Residential Builders Examination — 50 questions, 68% passing score (34 correct), 120-minute time limit.

How many attempts do I get, and what if I fail three times?
You get 3 attempts within your 12-month eligibility period. If you fail all three, you must wait 12 months from your last attempt before testing again.

How do I register?
Register online 24/7 at the exam registration page, or by phone at (855) 340-3701 (Mon–Fri 7:30 am–10:00 pm, Sat–Sun 9:00 am–5:30 pm ET). You must have received an Examination Eligibility letter from the state before registering with PSI.

What ID do I need?
One valid, non-expired, government-issued photo ID that also has your signature — a state driver's license, state ID, US passport, US military ID, US Alien Registration Card, or Canadian government-issued ID. The name must match your registration exactly.

Can I bring a calculator?
Yes — a silent, non-printing, non-programmable, battery-operated calculator with no alphabetic keyboard. No paper tape printing.

Get Started

You know the format, you know the topics, and you know what it takes to pass. Now go do the work. Start with the free practice exam to see where you stand, then move to the full practice exam for serious prep with a topic-by-topic score breakdown. Get your books tabbed, put in the reps, and walk into that PSI center ready.