Tennessee CMC-A Mechanical Plumbing

Tennessee CMC-A Mechanical Plumbing Contractor Exam: Complete 2026 Study Guide

You've put in the years on the job. Now you need the license to prove it. The Tennessee CMC-A exam — officially the Tennessee mechanical plumbing contractor exam — is your gateway to working as a licensed mechanical plumbing contractor in Tennessee. It's a serious test: 110 questions, nearly five hours, and a passing score of 73%. But here's the good news — it's open book, and with the right preparation, it's very passable.

This guide covers everything you need to know: exam structure, topic weights, sample questions, required books, and study strategies that actually work. Whether you're just starting to plan or you're two weeks out from test day, you're in the right place. Start with our free practice exam to see where you stand today.

Tennessee CMC-A Exam Overview

The Tennessee CMC-A practice exam and the real thing share the same structure — so understanding the format now saves you surprises later.

• Questions: 110 scored questions
• Time limit: 295 minutes (just under 5 hours)
• Passing score: 73%, which equals 81 correct answers out of 110
• Format: Multiple choice, open book
• Administered by: PSI Exams
• Registration: exam registration page

This is an open-book exam, which means you bring your own approved references. That changes how you prepare. You're not memorizing code sections — you're learning how to find them fast under pressure. The clock is still running, and 295 minutes goes faster than you'd expect across 110 questions.

Before you can schedule with PSI, you'll need pre-approval from the Tennessee Board for Licensing Contractors. More on that in the FAQs below.

Topics Covered on the Tennessee CMC-A Exam

The exam spans nine topic areas. Here's how many of the 110 questions come from each — and where your study time should go.

Drain, Waste, and Vent (DWV) is the single biggest topic at 28 questions — more than a quarter of the exam. This covers drainage fixture unit values, pipe slope, cleanout placement, and indirect and special waste requirements. Know this cold.

Isometric Analysis is the second-largest area at 20 questions and trips up a lot of candidates. You'll calculate pipe lengths, fitting allowances, and offset calculations for multiple fitting angles. If geometry isn't your strong suit, budget extra time here.

Gas Appliances and Piping (12 questions) is the third-heaviest area. It covers combustion air, clearances, piping materials, pipe sizing methods, and pressure testing. This is where the International Fuel Gas Code 2021 becomes essential.

Spend the bulk of your prep on these three areas. The math and code knowledge they require take the most time to build.

Sample Questions from the TN Plumbing Contractor License Test

These questions reflect the real exam's style and difficulty. See how you do — but note that we don't reveal the answers here. Take the free practice exam to check your thinking.

Question 1 — Drain, Waste, and Vent Systems (Medium)

A 3-inch horizontal fixture branch drains a group of fixtures. What is the maximum number of drainage fixture units that may be connected to this branch?

• A) 20
• B) 48
• C) 12
• D) 36

This question tests your ability to apply DFU load tables from the IPC — exactly the kind of table-lookup skill the exam rewards.

Question 2 — Drain, Waste, and Vent Systems (Hard)

A macerating toilet assembly serving a single water closet must have a discharge opening of not less than what diameter?

• A) 1/2 inch
• B) 1-1/4 inches
• C) 1 inch
• D) 3/4 inch

Special waste and macerating equipment are niche areas — but they show up. Know where to find these sections fast.

Question 3 — Gas Appliances and Piping (Medium)

You are installing gas appliances in a mechanical room that serves a building. Using the standard method for indoor combustion air, what is the minimum required volume of the room per 1,000 Btu/h of total appliance input rating?

• A) 100 cubic feet
• B) 21 cubic feet
• C) 35 cubic feet
• D) 50 cubic feet

Combustion air calculations appear frequently in the gas section. The formula is in the IFGC — tab it.

Question 4 — Gas Appliances and Piping (Hard)

You are installing a suspended-type unit heater in a commercial warehouse. What is the minimum clearance required between the bottom of the unit heater and combustible materials?

• A) 12 inches
• B) 18 inches
• C) 6 inches
• D) 24 inches

Appliance clearance tables are a common source of exam questions. Learn how to cross-reference appliance type and material type quickly.

Question 5 — General Requirements (Easy)

What is the maximum opening size permitted for strainer plates on drain inlets to prevent rodents from entering a structure?

• A) 3/4 inch in least dimension
• B) 1/4 inch in least dimension
• C) 1 inch in least dimension
• D) 1/2 inch in least dimension

Short, specific code requirements like this one are easy points if your books are tabbed correctly.

What Types of Questions to Expect (by Topic)

Our full practice exam pool contains 747 questions across all nine topic areas. Here's what each topic looks like in practice:

• General Knowledge and Math (132 practice questions): Arithmetic, unit conversions, area and volume formulas, Pythagorean theorem, and pipe offset calculations. Expect to calculate travel lengths, diagonals, and rise-and-run figures.
• General Requirements (65 practice questions): Administrative procedures, structural requirements, backflow prevention, approved materials and supports, joint and connection types, storm drain rules, and system testing requirements.
• Water Supply and Distribution (93 practice questions): Cross-connection control, backflow prevention device selection, pipe materials and joining methods, pressure-reducing valves, booster systems, and thermal expansion requirements.
• Fixtures, including Water Heaters (55 practice questions): Fixture counts by occupancy, installation clearances, shower valve temperature requirements, and water heater safety devices including relief valves and discharge piping.
• Drain, Waste, and Vent Systems (111 practice questions): DFU values, pipe sizing, horizontal slope requirements, cleanout placement, indirect waste connections, and special waste systems. This is the biggest topic on the real exam — treat it accordingly.
• Traps, Cleanouts, and Interceptors (39 practice questions): Trap types (including prohibited configurations), seal depth, grease interceptors, and cleanout access requirements.
• Isometric Analysis (166 practice questions): Center-to-center and end-to-end calculations, fitting allowances for threaded/copper/PVC fittings, 45-degree offset math, and multi-angle offset problems using trigonometric constants.
• Gas Appliances and Piping (60 practice questions): Combustion air requirements, appliance clearances, gas piping materials (CSST, polyethylene, metallic), pipe sizing using longest-length and branch-length methods, and pressure testing.
• OSHA Safety (26 practice questions): Employer safety program responsibilities, PPE requirements, fall protection systems, excavation cave-in protection, and confined space permit procedures.

Required Study Materials for the Tennessee CMC-A Exam

Because the exam is open book, your reference materials are your most important tool — both for study and on test day. The approved books are:

Mathematics for Plumbers and Pipefitters — This 8th-edition text by Lee Smith is required for the math and isometric analysis portions. Offset calculations, pipe lengths, and fitting allowances all come from methods covered here. Work through the practice problems — don't just read them.

International Plumbing Code 2021 — The IPC is your primary code reference for DWV systems, water supply, fixtures, traps, cleanouts, and general requirements. Most of your exam questions point back to this book. Tab every major table and chapter.

International Fuel Gas Code 2021 — The IFGC covers everything in the gas section: combustion air, appliance clearances, piping materials, and pipe sizing tables. Get comfortable with the sizing appendices — they're dense but very testable.

OSHA 29 CFR 1926 — The construction industry safety standards cover the four OSHA questions on the exam. It's a smaller topic by question count, but the material is specific and unfamiliar to many candidates. Tab the fall protection and excavation sections.

You may highlight and tab these books before the exam. You may not write notes in them. Use permanent index tabs — they're worth the investment.

Study Tips for the Tennessee CMC-A Exam

Master your books, not just the content. On an open-book exam, the fastest candidates win. Buy your books early, highlight key tables, and use permanent tabs on every chapter you'll need. Practice opening to the right page in under ten seconds. That speed is what separates a pass from a fail.

Work through every question once, then go back. Answer what you know, skip what you don't, and flag uncertain questions for review. Don't sink five minutes into one question while the clock runs. Our full practice exam mirrors the real exam — same question count, same time limit — so you can practice exactly this strategy.

Give yourself three to six weeks. Use the official exam bulletin as your roadmap. Focus your prep on DWV systems and isometric analysis first — those two topics alone account for 48 of your 110 questions. Aim for three clean practice-exam passes at 80% or higher before you test; the extra margin matters.

Practice timed. Exam-clock anxiety is real, but it's beatable. Run timed practice sessions until the format feels routine. By test day, you want the pacing to be automatic.

Frequently Asked Questions

Do I need pre-approval before registering for the Tennessee CMC-A exam?
Yes. You must complete the Exam Approval Request form and submit it to the Tennessee Board for Licensing Contractors. PSI will not allow you to schedule until your experience has been confirmed. Start this process early — it can take time. Visit the state licensing website for the current requirements and form.

What experience do I need to qualify?
You must show at least three years of plumbing work experience. This requirement was established by Senate Bill 0786 and HB 2122, which took effect May 24, 2007.

How much does the exam cost?
The Trade Portion costs $57, and the Business and Law portion costs $57 — each charged separately. Exam fees are non-refundable and non-transferable.

How many questions are on the exam and how long do I have?
The exam has 110 scored questions and you have 295 minutes to complete it.

What score do I need to pass?
You need to answer at least 73% of questions correctly — that's 81 out of 110.

Is the exam open book?
Yes. You bring your own approved reference materials to the testing center. Highlighting, underlining, and permanent index tabs are all permitted. You may not write notes in your books.

What references can I bring?
The approved references are the International Plumbing Code 2021, the International Fuel Gas Code 2021, Mathematics for Plumbers and Pipefitters (8th Edition by Lee Smith), and OSHA 29 CFR Part 1926 with latest amendments.

Can I use a calculator?
Yes — but only a silent, nonprinting, non-programmable calculator. Calculators with paper tape or an alphabetic keyboard are not permitted.

How soon can I retake the exam if I fail?
You cannot reschedule on the same day you tested. If you fail on a Monday, you can call Tuesday and potentially retest as early as Wednesday, depending on seat availability.

What ID do I need to bring?
One valid, unexpired, government-issued photo ID that includes your signature — such as a driver's license, U.S. passport, military ID, or similar. The ID must be a permanent physical card; temporary or paper versions are not accepted.

You're Ready to Start Preparing

The TN plumbing contractor license test is demanding, but it's structured and predictable. You know exactly how many questions come from each topic, you know the books to bring, and you know the score you need. That's a lot of the battle right there.

Start by taking our free practice exam — no account required, 10 questions, instant feedback. When you're ready to go deeper, the full practice exam gives you 110 questions, a real time limit, and a topic-by-topic score breakdown so you know exactly where to focus. You've got 747 practice questions available across all nine topics. Use them.

Get your books, tab them up, and start the clock. Your license is worth the work.