Minnesota Plumbing Exam

Two Exams, One Testing Vendor

Minnesota's individual plumber trade exams — journeyman and master — are administered through Prometric at authorized testing centers in Minneapolis, St. Paul, Rochester, Duluth, and other regional locations. These are the DLI's exams, not contractor or business-law tests (those use PSI Exams as a separate vendor).

Exam Format Breakdown

Journeyman Exam: 80 multiple-choice questions, 3.5-hour time limit. Covers water supply sizing, drainage capacity, venting rules, fixture traps, backflow prevention, plan reading, and code navigation.

Master Exam: 100 multiple-choice questions, 4-hour time limit. Includes everything on the journeyman exam plus advanced sizing calculations, isometric drawing analysis, complex plan review, water supply design, and regulatory compliance standards.

Both exams require a 70% score to pass. Results are issued immediately at the testing center.

What's Allowed in the Testing Room

Both exams are closed-book. You cannot bring your own code books, notes, tabs, or study aids. The testing center provides:

• Reference sheets
• Mathematical sizing tables
• Isometric diagrams
• A standard desktop calculator

This is a common point of confusion. Many candidates assume they can bring a tabbed code book — they can't. The exam tests whether you can navigate provided reference materials under time pressure.

How to Schedule

The sequence starts with approval, not with Prometric:

1. Submit an exam application through the DLI iMS portal
2. Pay the $50 exam fee
3. Wait for DLI to review your experience records (Form CC0100 submissions)
4. Receive an approval email from DLI
5. Schedule your test date through Prometric

You can't book a Prometric slot until DLI approves your application. The experience review is the potential bottleneck — incomplete or inconsistent CC0100 forms delay the process.

Retake Rules

If you fail, the mandatory wait period is 30 days before you can submit a new application and pay another $50 fee. A failed attempt doesn't invalidate your underlying application during its standard review window — you don't have to re-verify your hours each time.

That said, each retake is a fresh $50 fee and a month of waiting, so there's a real cost to going in underprepared.

Contractor Exams Are a Separate Track

If you're pursuing a general residential building or specialty contractor license that extends beyond standard plumbing, those exams go through PSI Exams (not Prometric). These typically include a trade-knowledge portion and a business-and-law portion covering contract law, mechanics' liens, tax compliance, workers' comp, and occupational safety. Same 70% passing threshold.

For the standard plumbing contractor license, there's no separate business exam — the requirement is an active master plumber designated as the company's RLI.

The Minnesota Plumber License Guide covers the full exam application timeline and maps the path from experience verification through scheduling and activation.

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