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Question 1

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Oregon uses the Oregon Specialty Plumbing Code (OSPC), which is based on which national plumbing code?

Uniform Plumbing Code (UPC)

International Plumbing Code (IPC)

National Standard Plumbing Code (NSPC)

NFPA 5000 Plumbing Chapter

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Key Facts: OR Plumber Exam

70%

Passing Score

Building Codes Division

100

Questions

3 hours

~$100+$265

Exam Fee

PSI

OSPC (based on UPC)

Code

Building Codes Division

Oregon's journeyman plumber exam is administered by PSI on behalf of the Building Codes Division. It has approximately 100 questions with a 3 hours time limit and requires 70% to pass. The exam fee is ~$100+$265. Oregon uses the OSPC (Oregon Specialty Plumbing Code, based on UPC) as its plumbing code.

Sample OR Plumber Practice Questions

Try these sample questions to test your OR Plumber exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Oregon uses the Oregon Specialty Plumbing Code (OSPC), which is based on which national plumbing code?

A.Uniform Plumbing Code (UPC)

B.International Plumbing Code (IPC)

C.National Standard Plumbing Code (NSPC)

D.NFPA 5000 Plumbing Chapter

Explanation: Oregon's Specialty Plumbing Code (OSPC) is based on the Uniform Plumbing Code (UPC) published by IAPMO, with Oregon-specific amendments adopted by the Building Codes Division. Plumbers must know both the UPC foundation and Oregon's specific modifications to pass the journeyman exam.

2Under Oregon's OSPC, what is the minimum size drain pipe for a water closet?

A.3 inches

B.4 inches

C.2 inches

D.1-1/2 inches

Explanation: Per the OSPC (based on UPC), the minimum drain size for a water closet is 3 inches. This matches the UPC requirement and ensures adequate flow capacity for toilet discharge. The building drain receiving water closet discharge must also be at least 3 inches.

3According to Oregon's Building Codes Division, who administers the journeyman plumber licensing exam?

A.PSI (testing vendor for Oregon BCD)

B.Pearson VUE

C.Prometric

D.Oregon Building Codes Division directly

Explanation: Oregon's journeyman plumber exam is administered by PSI on behalf of the Building Codes Division (BCD). Candidates must apply through BCD and receive authorization before scheduling with PSI. The exam tests knowledge of the OSPC and Oregon plumbing regulations.

4Under Oregon's OSPC, what is the minimum slope for a 4-inch horizontal drainage pipe?

A.1/8 inch per foot

B.1/4 inch per foot

C.1/2 inch per foot

D.1/16 inch per foot

Explanation: Per the UPC-based OSPC, horizontal drainage pipes 3 inches and larger require a minimum slope of 1/8 inch per foot (approximately 1% grade). Pipes smaller than 3 inches require 1/4 inch per foot. The slope ensures self-scouring velocity to carry solids through the system.

5Per Oregon's OSPC, what is the fixture unit value for a residential water closet (1.6 GPF or less)?

A.3 DFU

B.4 DFU

C.2 DFU

D.6 DFU

Explanation: Under the UPC (and Oregon's OSPC), a residential water closet rated at 1.6 GPF or less is assigned 4 DFU. Note that this differs from the IPC, which assigns 3 DFU. Oregon exam candidates must know the UPC-based values, not the IPC values.

6Under Oregon's OSPC, what is the minimum trap seal depth?

A.2 inches

B.3 inches

C.1 inch

D.4 inches

Explanation: The OSPC (UPC-based) requires a minimum trap seal of 2 inches and a maximum of 4 inches. The trap seal prevents sewer gases from entering the building. Trap seals can be lost through evaporation, siphonage, or back-pressure if the system is not properly vented.

7Per Oregon's OSPC, what is the maximum distance a 1-1/2 inch P-trap can be from its vent?

A.5 feet (60 inches) developed length

B.6 feet

C.8 feet

D.3-1/2 feet

Explanation: Per UPC Table 1002.2, the maximum distance from a 1-1/2 inch trap to its vent is 6 feet developed length. This distance ensures the vent can adequately protect the trap seal from siphonage. Exceeding this distance requires either a larger trap arm or relocation of the vent.

8Under Oregon's OSPC, what type of backflow preventer is required for a high-hazard cross-connection?

A.Reduced pressure principle (RP) backflow preventer

B.Atmospheric vacuum breaker

C.Dual check valve

D.Pressure vacuum breaker

Explanation: Oregon's OSPC requires a reduced pressure principle (RP) backflow preventer for high-hazard (health hazard) cross-connections. The RP device protects against both backsiphonage and backpressure conditions. It contains two independently acting check valves with a pressure differential relief valve between them.

9Per Oregon's OSPC, what is the minimum vent pipe size?

A.1-1/4 inches

B.1 inch

C.1-1/2 inches

D.2 inches

Explanation: The OSPC (UPC-based) sets the minimum vent pipe size at 1-1/4 inches. Additionally, the vent must be at least one-half the size of the drain it serves. Individual vents for water closets must be at least 2 inches in diameter.

10In Oregon, what is the maximum static water pressure permitted in a building distribution system per the OSPC?

A.80 psi

B.60 psi

C.100 psi

D.120 psi

Explanation: The OSPC limits maximum static water pressure to 80 psi. When incoming pressure exceeds 80 psi, an approved pressure-reducing valve must be installed. This protects fixtures, appliances, and piping from damage caused by excessive pressure.

About the OR Plumber Exam

Oregon-specific journeyman plumber licensing exam based on the OSPC (Oregon Specialty Plumbing Code, based on UPC) covering drainage, water supply, venting, gas piping, and fixtures

Questions

100 scored questions

Time Limit

3 hours

Passing Score

70%

Exam Fee

~$100+$265 (Building Codes Division / PSI)

OR Plumber Exam Content Outline

25%

Drainage Systems & Pipe Sizing

Drain sizing, fixture units (DFU), slope requirements, cleanouts, building drain and sewer sizing per OSPC (based on UPC)

20%

Water Supply & Distribution

Pipe sizing, backflow prevention, pressure regulation, cross-connection control, and water service requirements

20%

Venting Systems

Vent sizing, wet venting, air admittance valves, vent termination, circuit venting, and combination waste and vent

15%

Fixtures & Appliances

Fixture installation, clearances, water heaters, accessible fixtures, and commercial fixture requirements

10%

Gas Piping

Gas pipe sizing, appliance venting, pressure testing, BTU calculations, CSST bonding, and combustion air

10%

Code Administration & Special Systems

Permits, inspections, plan review, Oregon state amendments, medical gas, grease interceptors, and storm drainage

How to Pass the OR Plumber Exam

What You Need to Know

Passing score: 70%
Exam length: 100 questions
Time limit: 3 hours
Exam fee: ~$100+$265

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

OR Plumber Study Tips from Top Performers

1Master DFU values and drain pipe sizing — heavily tested on every exam

2Memorize minimum pipe sizes, slopes, and fixture clearances from code tables

3Practice backflow prevention device selection for different hazard levels

4Study gas piping sizing, pressure testing, and combustion air requirements

5Learn to navigate the OSPC (based on UPC) index quickly for efficient code lookup

6Review water heater installation including T&P valve requirements

7Practice with timed exams to develop time management skills

8Focus on venting methods — wet venting, circuit venting, and AAV rules

Frequently Asked Questions

What plumbing code does Oregon use?

Oregon uses the OSPC (Oregon Specialty Plumbing Code, based on UPC) for its plumbing licensing exam. Candidates should study the current adopted edition with any state-specific amendments.

Who administers the Oregon plumber exam?

The exam is administered by PSI on behalf of the Building Codes Division. Register through PSI after your application is approved.

What is the passing score?

Oregon requires 70% to pass the journeyman plumber exam. The exam has 100 questions with a 3 hours time limit.

Is the exam open book?

Most PSI-administered plumbing exams allow a bound copy of the adopted plumbing code. No loose pages, handwritten notes, or electronic devices are permitted. Check current exam policies before your test date.