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Exam Review

Key Facts: MN Plumber Exam

70%

Passing Score

DLI examination guide

240 points

Journeyworker Exam Scoring

DLI examination guide; not an item count

5.5 hours

Time Limit

DLI exam schedule and guide

2018 UPC + MN

2020 Minnesota Plumbing Code Base

Minnesota DLI

$50

Examination Application Fee

DLI plumbing license basics

Prepare with the 2020 Minnesota Plumbing Code (2018 UPC plus Minnesota amendments). The DLI journeyworker exam is 240 points over 5.5 hours, with 70% required to pass and a $50 examination application fee. Exam points must not be treated as a published question count.

Sample MN Plumber Practice Questions

Try these sample questions to review concepts for the MN Plumber exam. Each question includes a detailed explanation. Start the interactive quiz above for the full 298+ question experience with AI tutoring.

1Per the MPC as adopted by Minnesota, what is the minimum slope for a 4-inch horizontal drain 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 the Minnesota Plumbing Code (MPC, state-specific), horizontal drainage pipes 4 inches and larger require a minimum slope of 1/8 inch per foot. Pipes 3 inches or smaller require 1/4 inch per foot minimum slope.
2Per the MPC, what is the DFU value for a floor-mounted water closet (1.6 GPF)?
A.2 DFU
B.3 DFU
C.4 DFU
D.6 DFU
Explanation: Per the Minnesota Plumbing Code (MPC, state-specific) fixture unit table, a floor-mounted water closet with a 1.6 GPF rating has a DFU value of 4. This is the standard value used for drainage system sizing.
3What is the minimum building drain size for a system with 200 DFUs per the MPC as adopted by Minnesota?
A.3 inches
B.4 inches
C.5 inches
D.6 inches
Explanation: Per the Minnesota Plumbing Code (MPC, state-specific) drainage sizing tables, a 4-inch building drain at 1/8 inch per foot slope can handle up to approximately 216 DFUs, so 4 inches is adequate for 200 DFUs.
4Per the MPC, cleanouts in horizontal drains must be installed at intervals not exceeding what distance?
A.50 feet
B.75 feet
C.100 feet
D.125 feet
Explanation: Per the Minnesota Plumbing Code (MPC, state-specific), cleanouts must be installed at maximum 100-foot intervals in horizontal drainage lines. They are also required at changes of direction and at the upper terminal of the building drain.
5Per the MPC, what is the minimum slope for a 2-inch horizontal drain 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 the Minnesota Plumbing Code (MPC, state-specific), horizontal drainage pipes 3 inches and smaller (including 2-inch) require a minimum slope of 1/4 inch per foot to maintain adequate flow velocity.
6Per the MPC as adopted by Minnesota, a lavatory has what DFU value?
A.0.5 DFU
B.1 DFU
C.1.5 DFU
D.2 DFU
Explanation: Per the Minnesota Plumbing Code (MPC, state-specific) fixture unit table, a lavatory has a DFU value of 1. This is one of the lowest individual fixture DFU ratings.
7What is the minimum trap size for a kitchen sink per the MPC?
A.1-1/4 inches
B.1-1/2 inches
C.2 inches
D.3 inches
Explanation: Per the Minnesota Plumbing Code (MPC, state-specific), the minimum trap and drain size for a kitchen sink is 1-1/2 inches.
8Per the MPC, what fitting is required for a horizontal-to-horizontal direction change in drainage piping?
A.Short-sweep quarter bend
B.Long-sweep quarter bend or equivalent
C.Standard tee fitting
D.Any available fitting
Explanation: Per the Minnesota Plumbing Code (MPC, state-specific), horizontal-to-horizontal changes of direction must use long-sweep fittings. Short-sweep fittings are restricted to horizontal-to-vertical transitions.
9Per the MPC, indirect waste from a commercial dishwasher must discharge through what?
A.A direct connection to the building drain
B.An air gap to an approved receptor
C.A check valve
D.A backwater valve
Explanation: Per the Minnesota Plumbing Code (MPC, state-specific), indirect waste from commercial food equipment must discharge through an air gap into an approved floor sink or receptor to prevent contamination.
10Per the MPC, what is the maximum DFU load on a 3-inch horizontal branch at 1/4 inch per foot slope?
A.20 DFU
B.27 DFU
C.36 DFU
D.42 DFU
Explanation: Per the Minnesota Plumbing Code (MPC, state-specific) drainage table, a 3-inch horizontal branch at 1/4 inch per foot slope handles a maximum of 36 DFUs.

About the MN Plumber Exam

The Minnesota DLI journeyworker plumber licensing examination is based on the 2020 Minnesota Plumbing Code, which incorporates the 2018 Uniform Plumbing Code with Minnesota amendments. DLI publishes a 240-point examination, a 5.5-hour limit, and a 70% passing standard. A fixed question count is not published. DLI supplies authorized code and laws/rules references and a calculator.

Exam sponsor: Minnesota Department of Labor and Industry. The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

Question count not published by the exam provider

Time Limit

5.5 hours

Passing Score

70%

Exam / Certification Fees

$50 examination application fee

Exam sponsor website

Reported exam pass rate: Not published. Minnesota DLI does not publish a first-time pass-rate percentage in the cited examination resources. Exam sponsor website

Fees, eligibility, and exam policies can change. Confirm them with the exam sponsor before applying or paying.

Official sources

Our practice resources: topics covered

We aim to reflect publicly available exam outlines and topic information in our study resources. Coverage, format, and difficulty may differ from the actual exam, and we cannot guarantee that every detail is accurate or current. Confirm exam requirements, fees, and policies with the official exam sponsor.

Study topic; official weighting not published

Drainage Systems

Drain pipe sizing, fixture unit calculations, slope requirements, cleanouts, building sewers, indirect waste, and special drainage per Minnesota Plumbing Code

Study topic; official weighting not published

Water Supply Systems

Water pipe sizing, fixture unit calculations, backflow prevention, pressure regulation, water heaters, cross-connection control per MPC

Study topic; official weighting not published

Venting Systems

Vent sizing, wet and circuit venting, vent termination, and applicable Minnesota Plumbing Code requirements.

Study topic; official weighting not published

Fixtures & Appliances

Fixture installation, clearances, accessible fixtures, commercial fixtures, water closets, lavatories, showers, and bathtubs per MPC

Study topic; official weighting not published

Code Administration & Minnesota Regulations

Minnesota plumbing licensing rules, permits, inspections, plan review, and MPC-specific administrative requirements

Study topic; official weighting not published

Materials, Joints & Special Systems

Approved pipe materials, joints, hangers and supports, storm drainage, and other systems within the applicable license scope.

Preparing for the MN Plumber Exam

What You Need to Know

  • Passing score: 70%
  • Assessment: Question count not published by the exam provider
  • Time limit: 5.5 hours
  • Exam / certification fees: $50 examination application fee Official sources

Using Our Practice Resources

  • Work through all 298 available questions
  • Review every answer and explanation
  • Track weak areas and revisit them
  • Use our AI tutor for tough concepts

MN Plumber: Suggested Study Strategy

1Study the 2020 Minnesota Plumbing Code: 2018 UPC with Minnesota amendments, including Chapter 4714.
2Practice time management for the 5.5-hour exam — allocate time proportionally to each section's point value
3Practice fixture-unit and pipe-sizing calculations using Minnesota-adopted tables and amendments.
4Review MPC venting requirements carefully — wet venting and circuit venting rules are state-specific
5Study Minnesota-specific regulations on materials, inspections, and licensing requirements
6Practice drain pipe sizing using MPC tables and slope requirements
7Review backflow prevention and cross-connection control per Minnesota regulations
8Take full-length timed practice exams to build stamina for the 5.5-hour test duration

Frequently Asked Questions

How hard is the Minnesota journeyworker plumber exam?

DLI does not publish a first-time pass rate. The official examination guide describes a 240-point exam with a 5.5-hour limit and a 70% passing standard; preparation should combine practical experience with the adopted Minnesota code.

What plumbing code does Minnesota use?

The 2020 Minnesota Plumbing Code, Chapter 4714, incorporates the 2018 UPC with Minnesota amendments and took effect December 17, 2021. Use the Minnesota edition rather than an unamended national code.

How long is the Minnesota plumber exam?

DLI allows 5.5 hours for the journeyworker exam. The guide publishes 240 points, not a fixed item count. DLI provides the permitted code, laws/rules references, and a calculator.

How much does the Minnesota plumber exam cost?

DLI lists a $50 examination application fee. License issuance, renewal, and optional preparation materials are separate. A failed applicant must wait at least 30 days before reapplying.