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Under the Hawaii State Plumbing Code (UPC), what is the minimum size of a building sewer?

2 inches

3 inches

4 inches

6 inches

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Key Facts: HI Plumber Exam

70%

Passing Score

Hawaii Board of Electricians and Plumbers

100

Questions

3 hours limit

~$330

Exam Fee

PSI

UPC

Code Base

Hawaii adoption

Hawaii's journeyman plumber exam is based on the UPC (Hawaii State Plumbing Code) and administered by PSI. Hawaii uses the UPC rather than the IPC. The Hawaii State Plumbing Code includes amendments for tropical climate, volcanic soil conditions, and island-specific water systems. The exam requires 70% to pass and tests drainage, water supply, venting, gas piping, and fixture knowledge.

Sample HI Plumber Practice Questions

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

1Under the Hawaii State Plumbing Code (UPC), what is the minimum size of a building sewer?

A.2 inches

B.3 inches

C.4 inches

D.6 inches

Explanation: Per UPC building sewer requirements, the minimum size is 4 inches under the UPC. This ensures adequate capacity for the building drainage load and allows for proper maintenance access.

2Per the Hawaii State Plumbing Code (UPC), what is the minimum slope for a 4-inch horizontal drainage pipe?

A.1/16 inch per foot

B.1/8 inch per foot

C.1/4 inch per foot

D.1/2 inch per foot

Explanation: Per UPC drainage slope tables, horizontal drainage pipes 3 inches and larger require a minimum slope of 1/8 inch per foot. This ensures adequate velocity (approximately 2 fps) to transport solids through the drainage system.

3What is the DFU value for a residential water closet (1.6 gpf) under the UPC?

A.2 DFU

B.3 DFU

C.4 DFU

D.6 DFU

Explanation: Per UPC fixture unit tables, a residential water closet with 1.6 gpf is rated at 4 DFU. This value is used for drainage and vent pipe sizing calculations throughout the plumbing system.

4Per the Hawaii State Plumbing Code (UPC), what is the maximum distance between cleanouts on a horizontal drainage pipe?

A.50 feet

B.75 feet

C.100 feet

D.150 feet

Explanation: Per UPC cleanout requirements, cleanouts must be installed at intervals not exceeding 100 feet on horizontal drainage lines. Proper cleanout spacing ensures the entire system can be maintained and cleared of blockages.

5Under Hawaii regulations, what type of backflow preventer is required for a high-hazard cross-connection?

A.Atmospheric vacuum breaker (AVB)

B.Pressure vacuum breaker (PVB)

C.Double check valve assembly (DCVA)

D.Reduced pressure zone (RPZ) assembly

Explanation: Per UPC backflow prevention requirements, a reduced pressure zone (RPZ) assembly is required for high-hazard cross-connections. The RPZ provides the highest level of protection with a relief valve between two check valves.

6Per the Hawaii State Plumbing Code (UPC), what is the minimum water supply pipe size for a bathtub with shower?

A.3/8 inch

B.1/2 inch

C.3/4 inch

D.1 inch

Explanation: Per UPC fixture supply sizing tables, the minimum supply pipe size for a bathtub with shower is 1/2 inch. This ensures adequate flow and pressure at the fixture for proper operation.

7What is the maximum water temperature setting for a residential water heater per the UPC?

A.110°F

B.120°F

C.140°F

D.180°F

Explanation: Per UPC hot water requirements, the maximum delivery temperature at residential fixtures is 120°F. Anti-scald devices or thermostatic mixing valves must limit output temperature to prevent burns.

8Per the Hawaii State Plumbing Code (UPC), what is the minimum trap seal depth for a standard plumbing fixture?

A.1 inch

B.2 inches

C.3 inches

D.4 inches

Explanation: Per UPC trap requirements, the minimum trap seal depth is 2 inches and the maximum is 4 inches. The water seal prevents sewer gases from entering the building through fixture drains.

9Under the Hawaii State Plumbing Code (UPC), what is the minimum vent pipe size?

A.3/4 inch

B.1 inch

C.1-1/4 inches

D.1-1/2 inches

Explanation: Per UPC venting requirements, the minimum vent pipe size is 1-1/4 inches. No vent pipe shall be less than 1-1/4 inches in diameter. The vent must also be at least one-half the diameter of the drain it serves.

10Per the Hawaii State Plumbing Code (UPC), what is the maximum static water pressure in a building distribution system?

A.60 psi

B.80 psi

C.100 psi

D.125 psi

Explanation: Per UPC water pressure requirements, water pressure shall not exceed 80 psi static. Where pressures exceed 80 psi, a pressure-reducing valve must be installed to prevent fixture damage and pipe noise.

About the HI Plumber Exam

Hawaii journeyman plumber exam administered by PSI under the Board of Electricians and Plumbers. Based on the Uniform Plumbing Code (UPC) with Hawaii State amendments. Tests drainage, water supply, venting, gas piping, and island-specific requirements.

Questions

100 scored questions

Time Limit

3 hours

Passing Score

70%

Exam Fee

~$330 (Hawaii Board of Electricians and Plumbers)

HI Plumber Exam Content Outline

25%

Drainage & Waste Systems

Drain sizing, DFU calculations, slope requirements, cleanouts per UPC

20%

Water Supply & Distribution

Pipe sizing, backflow prevention, water heaters, pressure regulation per UPC

20%

Venting Systems

Vent sizing, wet venting, AAVs, vent termination, circuit venting per UPC

15%

Gas Piping

Gas pipe sizing, appliance venting, pressure testing, BTU calculations per IFGC

20%

Fixtures, Materials & Hawaii Code

Fixture installation, materials, joints, permits, inspections, and Hawaii-specific requirements

How to Pass the HI Plumber Exam

What You Need to Know

Passing score: 70%
Exam length: 100 questions
Time limit: 3 hours
Exam fee: ~$330

Keys to Passing

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

HI Plumber Study Tips from Top Performers

1Master UPC drainage fixture unit (DFU) values and pipe sizing tables

2Study backflow prevention device selection and cross-connection control

3Memorize minimum pipe sizes, slopes, and clearances for common fixtures

4Practice gas pipe sizing calculations using IFGC tables

5Understand wet venting and circuit venting provisions in the UPC

6Learn Hawaii-specific permit and inspection requirements

Frequently Asked Questions

What code does Hawaii use for the plumber exam?

Hawaii uses the UPC (Hawaii State Plumbing Code). The exam covers drainage, venting, water supply, gas piping, and fixture requirements as adopted by the state.

Who administers the Hawaii plumber exam?

The exam is administered by PSI under the Hawaii Board of Electricians and Plumbers.

How many questions are on the Hawaii plumber exam?

The Hawaii plumber exam has approximately 100 questions with a 3 hours time limit. A score of 70% is required to pass.

Is the HI plumber exam open book?

Most PSI-administered plumber exams allow a bound copy of the adopted code. Check with the Hawaii Board of Electricians and Plumbers for approved reference materials.