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Per the Michigan Plumbing Code as adopted by Michigan, what is the minimum slope for a 4-inch horizontal drain pipe?

1/16 inch per foot

1/8 inch per foot

1/4 inch per foot

1/2 inch per foot

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Key Facts: MI Plumber Exam

70%

Passing Score

Michigan LARA

125

Exam Questions

Written + isometric

~$40

Exam Fee

PSI

MI/IPC

Code Base

Michigan adoption

The Michigan journeyman plumber exam is administered through PSI and overseen by LARA. The exam is unique with 125 questions that include both written knowledge and practical/isometric drawing components. Michigan uses the Michigan Plumbing Code (based on IPC). The isometric section tests your ability to interpret plumbing system drawings, which many candidates find challenging. Requires 70% to pass.

Sample MI Plumber Practice Questions

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

1Per the Michigan Plumbing Code as adopted by Michigan, 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 Michigan Plumbing Code (IPC-based), 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 Michigan Plumbing Code, 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 Michigan Plumbing Code (IPC-based) 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 Michigan Plumbing Code as adopted by Michigan?

A.3 inches

B.4 inches

C.5 inches

D.6 inches

Explanation: Per the Michigan Plumbing Code (IPC-based) 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 Michigan Plumbing Code, 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 Michigan Plumbing Code (IPC-based), 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 Michigan Plumbing Code, 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 Michigan Plumbing Code (IPC-based), 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 Michigan Plumbing Code as adopted by Michigan, a lavatory has what DFU value?

A.0.5 DFU

B.1 DFU

C.1.5 DFU

D.2 DFU

Explanation: Per the Michigan Plumbing Code (IPC-based) 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 Michigan Plumbing Code?

A.1-1/4 inches

B.1-1/2 inches

C.2 inches

D.3 inches

Explanation: Per the Michigan Plumbing Code (IPC-based), the minimum trap and drain size for a kitchen sink is 1-1/2 inches.

8Per the Michigan Plumbing Code, 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 Michigan Plumbing Code (IPC-based), horizontal-to-horizontal changes of direction must use long-sweep fittings. Short-sweep fittings are restricted to horizontal-to-vertical transitions.

9Per the Michigan Plumbing Code, 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 Michigan Plumbing Code (IPC-based), indirect waste from commercial food equipment must discharge through an air gap into an approved floor sink or receptor to prevent contamination.

10Per the Michigan Plumbing Code, 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 Michigan Plumbing Code (IPC-based) drainage table, a 3-inch horizontal branch at 1/4 inch per foot slope handles a maximum of 36 DFUs.

About the MI Plumber Exam

Michigan journeyman plumber licensing exam administered by PSI and overseen by LARA. Based on the Michigan Plumbing Code (derived from IPC) with 125 questions including written knowledge and practical/isometric drawing interpretation components. The isometric portion tests the ability to read and interpret plumbing system drawings. Requires 70% to pass.

Questions

125 scored questions

Time Limit

4 hours

Passing Score

70%

Exam Fee

~$40 (Michigan LARA (Department of Licensing and Regulatory Affairs))

MI Plumber Exam Content Outline

25%

Drainage Systems

Drain pipe sizing, DFU calculations, slope requirements, cleanouts, building sewers, indirect waste, and special drainage per Michigan Plumbing Code

20%

Isometric Drawings & Practical

Isometric drawing interpretation, pipe layout reading, system identification from drawings, fixture connection analysis, and practical plumbing system design

20%

Water Supply Systems

Water pipe sizing, WSFU calculations, backflow prevention, pressure regulation, water heaters, cross-connection control, and potable water protection

15%

Venting Systems

Vent sizing, wet venting, circuit venting, vent termination, combination waste and vent, and trap seal protection per Michigan code

10%

Gas Piping

Gas pipe sizing, BTU calculations, appliance venting, pressure testing, combustion air, and fuel gas code compliance

10%

Code Administration & Materials

Permits, inspections, approved materials, pipe materials, joint methods, hangers and supports, and Michigan-specific code amendments

How to Pass the MI Plumber Exam

What You Need to Know

Passing score: 70%
Exam length: 125 questions
Time limit: 4 hours
Exam fee: ~$40

Keys to Passing

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

MI Plumber Study Tips from Top Performers

1Practice reading isometric drawings extensively — Michigan's exam uniquely includes a practical/isometric component

2Study the Michigan Plumbing Code (IPC-based) and learn to navigate the code index quickly

3Master DFU calculations and drain pipe sizing using Michigan code fixture unit tables

4Practice interpreting isometric pipe layouts including identifying vent, drain, and supply lines

5Review backflow prevention device selection based on hazard level per Michigan code

6Study water heater installation requirements including T&P relief valve discharge

7Practice gas pipe sizing calculations using BTU input ratings and pipe length tables

8Understand Michigan-specific amendments to the IPC — these differ from national IPC standards

Frequently Asked Questions

How hard is the Michigan journeyman plumber exam?

The Michigan journeyman plumber exam is challenging with an estimated 50-60% pass rate. The exam has 125 questions including both written knowledge and isometric drawing interpretation. Michigan uses its own Plumbing Code (based on IPC) and requires 70% to pass. The isometric drawing component is particularly challenging for many candidates.

What is the isometric drawing component?

Michigan's journeyman plumber exam includes a practical/isometric drawing section where candidates must interpret plumbing system isometric drawings. Questions may require identifying pipe sizes, fixture connections, vent configurations, and drainage layouts from isometric views. This component tests real-world pipe reading skills.

What plumbing code does Michigan use?

Michigan uses the Michigan Plumbing Code, which is based on the International Plumbing Code (IPC) with Michigan-specific amendments administered by LARA. A clean copy is typically allowed as a reference during the PSI-administered exam.

How much does the Michigan plumber exam cost?

The Michigan journeyman plumber exam fee is approximately $40, making it one of the most affordable plumber exams in the country. Additional costs include application fees and code book. Check with LARA for the current fee schedule.