Free practice test — 12 questions with full explanations
Original CraftPATH practice questions. These are not real exam questions. Every answer includes the reasoning, why each wrong option fails, the code area it comes from, and the misconception it targets.
Question 1. A North Carolina P-II plumbing license limits the holder to:
North Carolina Law, Business and Safety · Medium · Objective: Distinguish the P-I and P-II classifications.
- A. Projects under a fixed dollar value in any occupancy
- B. Plumbing work on single-family detached residential structures (correct)
- C. Service and repair work only, with no new installation
- D. Work performed inside a single county
Correct answer: B. Plumbing work on single-family detached residential structures
Why this is right: P-II is the restricted plumbing classification tied to single-family detached residential work, while P-I is unrestricted. The dividing line is the type of structure, not a dollar value or a geographic boundary.
Why the other options are wrong:
- A. Projects under a fixed dollar value in any occupancy — The plumbing classifications are not separated by project value.
- C. Service and repair work only, with no new installation — P-II includes new residential installation, not just repairs.
- D. Work performed inside a single county — The license is statewide.
Where this shows up on the job: Taking a townhouse or small apartment project on a P-II license is the most common scope violation the board sees.
Code reference: N.C.G.S. Chapter 87, Article 2; NC Board rules
Common misconception: Assuming P-II means small jobs rather than a specific occupancy type.
Question 2. A licensed plumbing contracting business in North Carolina must:
North Carolina Law, Business and Safety · Medium · Objective: Understand the qualified individual requirement.
- A. Be owned outright by a licensed plumber
- B. List a qualified individual who has passed the board's examination (correct)
- C. Carry a minimum of ten employees
- D. Requalify with each new permit
Correct answer: B. List a qualified individual who has passed the board's examination
Why this is right: The license is held by the entity but rests on a listed qualified individual who passed the examination. If that person leaves, the business must requalify before it can lawfully continue contracting.
Why the other options are wrong:
- A. Be owned outright by a licensed plumber — Ownership structure is flexible; qualification is not.
- C. Carry a minimum of ten employees — There is no minimum headcount.
- D. Requalify with each new permit — Qualification is tied to the license, not to each permit.
Where this shows up on the job: Companies routinely stall mid-project when their qualifier retires without a replacement already examined.
Code reference: N.C.G.S. Chapter 87, Article 2
Common misconception: Believing the license belongs to the company independent of any person.
Question 3. Plumbing installations in North Carolina are judged against:
Administration, Scope and Code Navigation · Medium · Objective: Identify the governing technical code.
- A. The Uniform Plumbing Code as published
- B. The North Carolina State Plumbing Code, which adopts the International Plumbing Code with state amendments (correct)
- C. A code written independently by each city
- D. The National Standard Plumbing Code
Correct answer: B. The North Carolina State Plumbing Code, which adopts the International Plumbing Code with state amendments
Why this is right: North Carolina adopts the IPC with state amendments as part of the State Building Code, and the adopted edition, not the newest model code published, governs inspections and the exam.
Why the other options are wrong:
- A. The Uniform Plumbing Code as published — North Carolina is an IPC state, not a UPC state.
- C. A code written independently by each city — Local jurisdictions enforce the state code rather than writing their own.
- D. The National Standard Plumbing Code — The NSPC is not the adopted model code here.
Where this shows up on the job: Candidates who study a UPC prep book miss table values and venting rules that differ between the model codes.
Code reference: North Carolina State Building Code: Plumbing Code
Common misconception: Assuming all states use the same plumbing model code.
Question 4. A 3-inch horizontal sanitary drain is generally required to have a minimum slope of:
Drainage, Waste and Sizing · Hard · Objective: Apply minimum drain slope.
- A. 1/16 inch per foot
- B. 1/8 inch per foot (correct)
- C. 1/4 inch per foot
- D. 1/2 inch per foot
Correct answer: B. 1/8 inch per foot
Why this is right: Drains 3 inches and larger are permitted a minimum slope of 1/8 inch per foot, while drains 2 1/2 inches and smaller require 1/4 inch per foot. Larger pipe carries enough volume to keep solids moving at the shallower pitch.
Why the other options are wrong:
- A. 1/16 inch per foot — 1/16 inch per foot applies only to very large drains where the code allows it with approval.
- C. 1/4 inch per foot — 1/4 inch per foot is the small-diameter requirement.
- D. 1/2 inch per foot — 1/2 inch per foot is steeper than required and can outrun solids.
Where this shows up on the job: Overpitching a long 4-inch building drain lets water race ahead of the solids and leaves a blockage behind.
Code reference: NC Plumbing Code Chapter 7, drainage pipe slope
Common misconception: Believing steeper is always better.
Question 5. Cleanouts in a horizontal building drain are required at intervals of not more than:
Drainage, Waste and Sizing · Hard · Objective: Apply cleanout spacing.
- A. 50 feet
- B. 100 feet (correct)
- C. 150 feet
- D. 200 feet
Correct answer: B. 100 feet
Why this is right: The code caps the spacing of cleanouts in horizontal drainage lines at 100 feet of developed length, plus cleanouts at aggregate direction changes and at the junction of the building drain and building sewer.
Why the other options are wrong:
- A. 50 feet — 50 feet is more frequent than the code requires for these lines.
- C. 150 feet — 150 feet exceeds the required spacing.
- D. 200 feet — 200 feet exceeds the required spacing.
Where this shows up on the job: Missed cleanouts at aggregate 135-degree direction change are a routine inspection failure.
Code reference: NC Plumbing Code Chapter 7, cleanouts
Common misconception: Counting only straight runs and ignoring the aggregate change of direction rule.
Question 6. Except where a deep seal trap is specifically required, a fixture trap seal must be at least:
Venting and Traps · Hard · Objective: Apply trap seal depth limits.
- A. 1 inch and not more than 2 inches
- B. 2 inches and not more than 4 inches (correct)
- C. 3 inches and not more than 6 inches
- D. 4 inches and not more than 8 inches
Correct answer: B. 2 inches and not more than 4 inches
Why this is right: A 2-inch minimum seal resists evaporation and siphonage, and the 4-inch maximum prevents a seal so deep that the fixture drains sluggishly and accumulates solids.
Why the other options are wrong:
- A. 1 inch and not more than 2 inches — A 1-inch seal evaporates and siphons too easily.
- C. 3 inches and not more than 6 inches — Deeper seals are used only where specifically required, such as certain interceptors.
- D. 4 inches and not more than 8 inches — That range is far outside the general requirement.
Where this shows up on the job: Floor drains in seldom-used areas need trap primers or a deep seal because evaporation breaks the seal and admits sewer gas.
Code reference: NC Plumbing Code Chapter 10, traps
Common misconception: Thinking a deeper trap seal is always safer.
Question 7. A 1 1/4-inch trap arm serving a lavatory has a maximum developed length to its vent of:
Venting and Traps · Hard · Objective: Apply trap arm limits for a lavatory.
- A. 2 feet 6 inches
- B. 3 feet 6 inches (correct)
- C. 5 feet
- D. 6 feet
Correct answer: B. 3 feet 6 inches
Why this is right: The trap-to-vent distance table caps a 1 1/4-inch trap arm at 3 feet 6 inches so the water level in the trap arm never rises high enough to seal the pipe and siphon the trap.
Why the other options are wrong:
- A. 2 feet 6 inches — 2 feet 6 inches is shorter than the table permits.
- C. 5 feet — 5 feet is the limit for a 1 1/2-inch trap arm.
- D. 6 feet — 6 feet is the limit for a 2-inch trap arm.
Where this shows up on the job: Long lavatory trap arms in remodels are the classic cause of a gurgling, sewer-gas-smelling bathroom.
Code reference: NC Plumbing Code Chapter 9, distance of trap from vent
Common misconception: Measuring straight-line distance instead of developed length.
Question 8. A hose connection at a boiler feed line under continuous pressure and exposed to a health hazard requires:
Water Supply, Distribution and Backflow · Hard · Objective: Select the correct backflow prevention device.
- A. An atmospheric vacuum breaker
- B. A reduced pressure principle backflow preventer (correct)
- C. A dual check valve
- D. An air gap is not acceptable
Correct answer: B. A reduced pressure principle backflow preventer
Why this is right: A reduced pressure principle assembly protects against both backsiphonage and backpressure under continuous pressure at a high-hazard connection. Boiler treatment chemicals make this a health hazard.
Why the other options are wrong:
- A. An atmospheric vacuum breaker — An atmospheric vacuum breaker cannot be under continuous pressure and does not protect against backpressure.
- C. A dual check valve — A dual check is a low-hazard device.
- D. An air gap is not acceptable — An air gap is the highest form of protection and is always acceptable where it can be built.
Where this shows up on the job: Chemically treated boiler water siphoning into potable piping is one of the documented cross-connection incidents behind these rules.
Code reference: NC Plumbing Code Chapter 6, protection of potable water supply
Common misconception: Choosing a device by cost instead of by hazard level and pressure condition.
Question 9. When static water pressure at a building exceeds 80 psi, the code requires:
Water Supply, Distribution and Backflow · Medium · Objective: Apply maximum water service pressure limits.
- A. A larger water service pipe
- B. An approved pressure reducing valve on the water distribution system (correct)
- C. An additional shutoff valve at each fixture
- D. Nothing, provided the piping is rated for the pressure
Correct answer: B. An approved pressure reducing valve on the water distribution system
Why this is right: Above 80 psi static pressure, a pressure reducing valve is required to protect fixtures, appliances and connections. High pressure drives leaks, water hammer and premature fixture failure.
Why the other options are wrong:
- A. A larger water service pipe — Pipe size affects flow and pressure loss, not static pressure.
- C. An additional shutoff valve at each fixture — Fixture stops are required regardless and do not address system pressure.
- D. Nothing, provided the piping is rated for the pressure — Pipe rating does not exempt the system from the requirement.
Where this shows up on the job: A failed PRV showing 120 psi at the hose bibb is a common cause of repeat supply-line and water heater failures.
Code reference: NC Plumbing Code Chapter 6, water pressure
Common misconception: Treating 80 psi as a recommendation rather than a code threshold.
Question 10. The discharge pipe from a water heater temperature and pressure relief valve must:
Fuel Gas, Water Heaters and Special Systems · Hard · Objective: Apply relief valve discharge piping rules.
- A. Be reduced one size below the valve outlet to increase velocity
- B. Be the full size of the valve outlet, run downward, and terminate with an air gap without a threaded end (correct)
- C. Be trapped near the floor to stop drafts
- D. Discharge into the nearest vent stack
Correct answer: B. Be the full size of the valve outlet, run downward, and terminate with an air gap without a threaded end
Why this is right: Full-size, downward-pitched, untrapped discharge with a visible air gap termination guarantees the valve can relieve freely and that a discharge is visible to the occupant. A threaded end invites someone to cap it.
Why the other options are wrong:
- A. Be reduced one size below the valve outlet to increase velocity — Reducing the line restricts relief flow and defeats the valve.
- C. Be trapped near the floor to stop drafts — A trap holds water and scale that can block discharge.
- D. Discharge into the nearest vent stack — Discharging into a vent or drainage system directly is not permitted.
Where this shows up on the job: Capped or reduced relief discharge lines are the single most cited water heater defect on inspections.
Code reference: NC Plumbing Code Chapter 5, water heater relief valve discharge
Common misconception: Treating the discharge line as ordinary drain piping.
Question 11. A water test on a DWV system requires the piping to hold water for at least 15 minutes with a head of not less than:
Administration, Scope and Code Navigation · Medium · Objective: Apply DWV test requirements.
- A. 5 feet
- B. 10 feet (correct)
- C. 15 feet
- D. 20 feet
Correct answer: B. 10 feet
Why this is right: The rough-in water test requires a 10-foot head above the section being tested, so joints see meaningful pressure and pinholes show themselves before the walls close.
Why the other options are wrong:
- A. 5 feet — 5 feet produces too little pressure to reveal marginal joints.
- C. 15 feet — 15 feet exceeds the required head.
- D. 20 feet — 20 feet exceeds the required head.
Where this shows up on the job: Filling to the top of the highest stack is the practical way inspectors see the required head satisfied.
Code reference: NC Plumbing Code Chapter 3, tests and inspections
Common misconception: Assuming an air test and a water test have the same acceptance criteria.
Question 12. A sewer trench that workers must enter generally requires protective systems such as sloping, shoring or shielding when it reaches a depth of:
North Carolina Law, Business and Safety · Medium · Objective: Apply excavation safety requirements.
- A. 3 feet
- B. 5 feet (correct)
- C. 8 feet
- D. 10 feet
Correct answer: B. 5 feet
Why this is right: OSHA requires cave-in protection in excavations 5 feet or deeper unless the excavation is entirely in stable rock, and a competent person must evaluate the soil and system daily.
Why the other options are wrong:
- A. 3 feet — 3 feet is below the trigger depth, though hazards can still exist.
- C. 8 feet — 8 feet is past the point where protection was already required.
- D. 10 feet — 10 feet is well past the trigger depth.
Where this shows up on the job: Trench collapse remains one of the deadliest hazards in underground plumbing work, and a cubic yard of soil weighs roughly as much as a small car.
Code reference: OSHA 29 CFR 1926 Subpart P
Common misconception: Judging trench safety by how the soil looks rather than by depth and a competent person's evaluation.
How to study for the North Carolina plumbing contractor exam
Confirm the adopted code edition first
North Carolina adopts the International Plumbing Code with state amendments on its own cycle, and the amendments are where candidates lose points. Buy the adopted edition of the state plumbing code, not a generic model code, and read the North Carolina amendments start to finish before you drill questions.
Master the sizing tables cold
Drainage fixture unit tables, horizontal branch versus stack sizing, trap-to-vent distances, and water distribution sizing account for most of the calculation questions. Work each table until you can identify which table applies from the wording of the question in under ten seconds.
Separate venting concepts
Individual, common, wet, circuit and island venting each solve a different problem. Sketch each configuration by hand until you can draw it from memory, because exam questions describe the arrangement in words and expect you to visualize it.
Do not skip the law and business material
P-I and P-II scope, the qualified individual requirement, permits and inspections, lien rights under N.C.G.S. Chapter 44A, insurance and OSHA excavation rules are all fair game and are the easiest points to bank because they do not require calculation.
Run a six-week plan
Week one: administration, definitions and navigation drills. Week two: drainage and sizing. Week three: venting and traps. Week four: water supply, distribution and backflow. Week five: fuel gas, water heaters and special systems. Week six: North Carolina law and business plus full-length timed sets.
Frequently asked questions
What is the difference between a P-I and a P-II license?
P-I is the unrestricted plumbing classification. P-II is restricted to plumbing work on single-family detached residential structures. The distinction is the type of structure, not the project value.
Does North Carolina issue a journeyman plumber license?
The state licenses plumbing contractors rather than issuing statewide journeyman licenses. Verify current classifications with the board, since restricted and specialty classifications also exist.
Who is the qualified individual?
The person listed with the license who passed the board's examination. A business that loses its qualified individual must requalify before continuing to contract.
Which plumbing code does the exam use?
The North Carolina State Plumbing Code, an adoption of the International Plumbing Code with state amendments, plus the state Fuel Gas Code where gas work is in scope.
How many questions are on the exam and what is passing?
The board publishes item counts, format and passing score in its current examination information. We leave those figures pending here rather than estimating them.
Are these real North Carolina exam questions?
No. Every question here is original CraftPATH material written to the same subject areas the exam covers. We do not reproduce live examination content.
How long should I study?
Experienced plumbers typically need six to ten weeks, weighted toward drainage and vent sizing, backflow device selection, and the North Carolina law and business material.