- Passing requires 44 of 65 scored questions correct (67.7%) within 180 minutes.
- Drain, Waste and Vent and Sewers carries 17 questions - the single largest domain.
- The exam is open-book: highlighting, underlining, and permanent tabs allowed; loose notes are not.
- Business Management and Law is a separate 50-question exam requiring 34 correct (68%).
Exam Snapshot: Numbers You Must Memorize
Before you touch a single practice question, lock in the core numbers governing the South Carolina Residential Specialty Contractor Plumbing Exam (SC-RSC-PL). These figures come straight from the PSI candidate bulletin administered on behalf of the South Carolina Residential Builders Commission, and they will not change based on which testing center you choose or which day you sit for the exam.
- Format: 65 scored multiple-choice questions, computer-delivered at a PSI test center.
- Time limit: 180 minutes for the trade exam.
- Passing score: 44 correct answers, equal to 67.7%.
- Pretest questions: PSI may insert 5-10 unscored pretest items; the extra time to answer them does not count against your 180-minute clock.
- Delivery: Open-book, computer-based testing at a PSI-approved center.
These numbers are the backbone of every study plan you build. If you want the fuller narrative behind them - including how the score is derived and why 44 is the magic number - read the dedicated breakdown in the SC-RSC-PL Passing Score 2026 guide.
Domain-by-Domain Quick Reference
The trade exam is built from eight domains with fixed question allocations. Memorizing these allocations tells you exactly where to invest study hours - weighting your review to match the exam's own weighting is the single highest-leverage move you can make.
| Domain | Questions | Share of Exam |
|---|---|---|
| 1. General Plumbing Knowledge and Regulations | 15 | Second-largest area |
| 2. Piping, Valves, and Controls | 6 | Moderate |
| 3. Fixtures and Equipment | 4 | Smaller |
| 4. Water Supply | 4 | Smaller |
| 5. Drain, Waste and Vent and Sewers | 17 | Largest area |
| 6. Isometric Analysis | 9 | Third-largest |
| 7. Safety | 4 | Smaller |
| 8. Specialty Applications | 6 | Moderate |
Notice that Domain 5, Domain 1, and Domain 6 together account for 41 of the 65 scored questions. That's nearly two-thirds of the exam concentrated in three domains. A candidate who masters Drain, Waste and Vent and Sewers, General Plumbing Knowledge and Regulations, and Isometric Analysis - but neglects the smaller domains entirely - still has a mathematically sound shot at passing. The reverse strategy, spreading equal effort across all eight domains, wastes hours on low-yield content.
Domain 5: Drain, Waste and Vent and Sewers
This is the highest-weighted domain on the entire exam at 17 questions. Expect scenario-based items requiring you to apply code minimums, not just recall them.
- Pipe sizing for drainage fixture units
- Venting configurations and minimum vent sizes
- Slope requirements and cleanout placement
- Sewer material compatibility and trench/backfill basics
Domain 1: General Plumbing Knowledge and Regulations
At 15 questions, this domain covers the regulatory backbone of residential plumbing work in South Carolina, plus foundational trade knowledge that threads through every other domain.
- Licensing scope and what "covered" residential plumbing work means
- Code adoption structure referencing the South Carolina IPC
- General terminology, definitions, and administrative provisions
Domain 6: Isometric Analysis
With 9 questions, isometric drawing interpretation is a skill domain, not a memorization domain. You must be able to trace a drawing and answer questions about it under time pressure.
- Reading developed length off an isometric riser diagram
- Calculating offsets and identifying pipe runs
- Tracing fixture connections through a drawn system
For a complete narrative walkthrough of every domain - including how the smaller domains like Fixtures and Equipment, Water Supply, and Safety fit into the bigger picture - see the SC-RSC-PL Exam Domains 2026 guide. If you're still assembling your overall study approach, the SC-RSC-PL Study Guide 2026 lays out a first-attempt strategy built around this same domain weighting.
Open-Book Rules and What You Can Bring
The SC-RSC-PL trade exam is open-book, but "open-book" at a PSI center has strict boundaries. Get this wrong and you risk having materials confiscated or invalidated on test day.
This means your prep work should happen before test day: permanently tab the sections you expect to reference (drainage fixture unit tables, vent sizing charts, trap standards) rather than planning to write notes during the exam. Practicing with the actual code references - not a summarized study guide alone - builds the muscle memory you'll need to find information fast under the 180-minute clock.
Fees, Licensing Path, and Attempt Limits
Passing the exam is only one piece of becoming a licensed Residential Plumber (RBP) under the South Carolina Residential Builders Commission. Here's the mechanical sequence and the state fees involved, separate from whatever PSI charges for the examination itself.
- Application fee: $135
- Initial licensure fee: $220
- Renewal fee: $220
- Renewal cycle: Biennially, by June 30 of odd-numbered years
- Surety bond: At least $10,000 in coverage required for undertakings exceeding $5,000 in combined labor and materials (this is the coverage amount, not the premium you pay)
Before you can even schedule with PSI, the Commission must approve your application. That approval hinges on documenting at least one year of relevant supervised experience, an experience affidavit signed by a qualifying licensed builder, general contractor, or plumber, supporting work-history records, a credit report, and proof of lawful presence. For the full eligibility checklist and how to assemble your paperwork, see SC-RSC-PL Requirements 2026. For a line-item cost breakdown across the entire licensing journey, check SC-RSC-PL Certification Cost 2026.
Key Takeaway
You have a one-year eligibility period to pass both the trade exam and the Business Management and Law exam. You're allowed three attempts; a third failure triggers a mandatory 12-month wait from your last attempt before you can try again.
Note also that covered residential specialty contracting work exceeding $500 legally requires the appropriate license - this threshold is why unlicensed side work can create real legal exposure, and it's part of why employers verify licensure status carefully when hiring.
Waiver Routes Worth Knowing
Not everyone starts from zero. Certain existing credentials may support a technical-exam waiver from the trade exam portion:
- Eligible exam-based North Carolina or Mississippi residential plumbing licenses
- South Carolina commercial mechanical plumbing licensure
- MASC master plumbing certification
Even with a waiver, the Commission's experience documentation requirements and the Business Management and Law examination still apply - a waiver shortens the technical testing path, not the entire licensing process.
Reference Books to Tab Before Test Day
Your open-book advantage is only as good as your familiarity with the references. Three documents anchor the trade exam:
- 2021 International Plumbing Code or the South Carolina IPC
- 2018 International Residential Code, South Carolina IRC, or IRC Commentary
- OSHA 29 CFR Part 1926 for Safety-domain items
For the separate Business Management and Law exam, preparation runs through NASCLA's South Carolina Residential Builders guide, eighth edition - notably not the commercial-contractors edition, which is a common mix-up that wastes study time on the wrong book.
Final-Week Review Priorities
Generic study techniques like spaced repetition or timed drills only matter if they're pointed at the right material. In your final week before sitting for the SC-RSC-PL trade exam, sequence your review by domain weight rather than by chapter order in your code book.
Drain, Waste and Vent and Sewers (17 questions)
- Drill drainage fixture unit sizing scenarios
- Review venting configuration rules and cleanout placement
General Plumbing Knowledge and Regulations (15) + Isometric Analysis (9)
- Re-read licensing scope and code adoption provisions
- Practice tracing developed length and offsets on isometric drawings
Piping, Valves, Controls + Specialty Applications (6 each)
- Review valve types and control functions
- Cover backflow prevention, water heaters, gas equipment, water treatment
Fixtures, Water Supply, Safety (4 each)
- Quick review of head pressure and friction loss calculations
- Confirm your permanent tabs are in place, not loose notes
This sequencing mirrors real point value: the domains you review first and longest are the domains that can single-handedly make or break your 44-correct threshold. If you want a broader sense of how tough candidates generally find this exam and where they tend to lose points, read How Hard Is the SC-RSC-PL Exam?. For context on outcomes across attempts, see SC-RSC-PL Pass Rate 2026.
Who This License Serves
Holding an active Residential Plumber (RBP) license under the South Carolina Residential Builders Commission qualifies you to perform covered residential plumbing specialty contracting work in the state - the kind of work that residential builders, remodeling contractors, and independent plumbing crews rely on licensed subcontractors to handle legally. If you're weighing whether pursuing this license fits your career trajectory, the ROI analysis and earnings guide lay out the considerations in more depth. For those still mapping out foundational terminology, start with What Is SC-RSC-PL? or SC-RSC-PL Meaning.
Once you're actively licensed, ongoing renewal requires maintaining the required bond coverage and renewing biennially by June 30 of odd-numbered years - mark that date now so it doesn't catch you off guard two years from now.
Ready to test your recall against the actual domain weightings? Run a full-length timed set on the main practice test platform before you commit to a PSI scheduling date - it's the fastest way to find out which of the eight domains still need work.
Frequently Asked Questions
You need 44 correct answers out of 65 scored questions, which equals 67.7%. This is separate from the Business Management and Law exam, which requires 34 out of 50 correct (68%).
No. Highlighting, underlining, and permanent tabs are allowed, but handwritten notes, removable tabs, and any extra loose or attached papers are prohibited at the PSI test center.
Drain, Waste and Vent and Sewers is the largest domain with 17 questions, followed by General Plumbing Knowledge and Regulations at 15 and Isometric Analysis at 9.
You are allowed three attempts within your one-year eligibility period. A third failure requires a mandatory 12-month wait from your last examination attempt before trying again.
A calculator is permitted but must be silent, nonprinting, and nonprogrammable. It's useful for domains involving head pressure, friction loss, and area or volume calculations.