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Contractor Licensing · CMC-A

Tennessee Contractor Mechanical Plumbing Contractor Examination Practice Test

The Tennessee Contractor Mechanical Plumbing Contractor Examination (CMC-A) practice material focuses on plumbing and mechanical system decisions in buildings. Its questions sample pipe selection and routing, fixture connections, water-pressure control, sanitary drainage, hydronic heating, combustion safety, and fire-rated penetrations—areas where installation details affect system performance and occupant safety.

Exam overview

Exam providerTennessee Board for Licensing Contractors
Exam codeCMC-A
CategoryContractor Licensing

About the Tennessee Contractor Mechanical Plumbing Contractor Examination Exam

Mechanical and plumbing work requires reading plans and specifications to identify where systems run, which materials apply, and how components connect. The sampled questions ask about practical judgments such as checking a fixture shutoff valve after replacement, understanding a pressure-reducing valve’s function, and avoiding drainage layouts that can impede flow. Hydronic-system concepts include distributing flow among branches, insulating piping, and recognizing how trapped air can affect circulation. Other questions address combustion-related occupant hazards and maintaining a fire-resistance barrier where piping crosses a rated wall. These subjects connect installation choices with water delivery, drainage, heating performance, and building safety. Practitioners also need to verify completed work through functional checks and coordinate piping details with the building conditions shown in project documents.

Sample Practice Questions

Review a selection from this exam's published US Practice Tests practice bank.

Question 1

On a plumbing or mechanical project, what is the most reliable first reference for the required pipe material and installation details at a specific location?

  1. AThe approved project documents and applicable adopted codes
  2. BA guess based on the appearance of nearby piping
  3. CAn unrelated product advertisement
  4. DA verbal assumption that no inspection will occur
Show answerCorrect answer: A

Approved drawings, specifications, manufacturer instructions, and applicable adopted codes establish the requirements for a particular installation. Conflicts or unclear conditions should be resolved through the project's formal clarification process before work proceeds.

Question 2

When installing a replacement plumbing fixture, why should the installer check that the shutoff valve operates and does not leak after use?

  1. ATo confirm the water supply can be isolated and the valve remains serviceable
  2. BTo determine the fixture's drainage slope
  3. CTo set the building's water-heater temperature
  4. DTo measure the vent stack's airflow
Show answerCorrect answer: A

A working, leak-free shutoff valve allows the fixture's water supply to be isolated for service and helps avoid leakage at the valve. It does not establish drainage slope or control unrelated system settings.

Question 3

A mechanical room contains a fuel-burning appliance. Which general practice helps protect occupants from hazards associated with combustion?

  1. AProvide combustion air and venting in accordance with the appliance instructions and applicable requirements
  2. BSeal every room opening regardless of appliance type
  3. CRoute the flue into a plumbing drain
  4. DUse the water-supply pipe as the appliance vent
Show answerCorrect answer: A

Fuel-burning equipment needs an appropriate supply of combustion air and a correctly designed venting arrangement to safely handle combustion products. Specific requirements depend on the appliance and applicable codes.

Question 4

A building drain must transition from a larger pipe to a smaller pipe in the direction of flow. What is the usual concern with making this reduction?

  1. AIt can restrict flow and promote blockage, so the design and applicable code must permit the transition
  2. BIt automatically increases the drain's capacity
  3. CIt eliminates the need for proper pipe slope
  4. DIt prevents solids from entering the drain
Show answerCorrect answer: A

Reducing a drain's size in the direction of flow can impede conveyance and increase the risk of blockage. Drain sizing and transitions should follow the approved design and applicable requirements.

Question 5

A water-supply system includes a pressure-reducing valve. What is the valve intended to do?

  1. AMaintain a lower, controlled downstream pressure when inlet pressure is higher
  2. BPrevent all water from flowing backward into the main
  3. CRemove suspended solids from the water
  4. DIncrease downstream pressure whenever a fixture opens
Show answerCorrect answer: A

A pressure-reducing valve lowers and regulates downstream pressure within its adjustment range. It is not a filter or a substitute for a backflow prevention device.

Question 6

In a hydronic heating circuit, what is the purpose of balancing the flow through multiple branches?

  1. ATo distribute flow so each branch receives an appropriate amount for the system design
  2. BTo make every branch operate at the same pipe temperature regardless of load
  3. CTo eliminate the need for a circulator
  4. DTo raise system pressure until all valves are fully open
Show answerCorrect answer: A

Balancing adjusts branch flow to better match the intended heat delivery. It helps avoid some areas receiving too little or excessive flow; it does not remove the need for circulation or correct system design.

Question 7

A pipe passes through a rated fire-resistance wall. What is generally needed at the penetration to preserve the wall's fire-resistance function?

  1. AAn approved firestop system suitable for the wall, penetrating material, and opening
  2. BOrdinary expanding foam selected only for convenience
  3. CA larger unsealed opening to prevent pipe contact
  4. DA layer of paint on the pipe only
Show answerCorrect answer: A

Penetrations can compromise a fire-resistance-rated assembly. A tested or approved firestop system should be appropriate to the assembly and the penetrating item and installed according to its listing and applicable requirements.

How to use this practice test

Access is free. The bank contains 50 published questions; a practice session presents up to 20 questions selected at random. Submit your answers to see session results, then use missed items to identify which plumbing or mechanical concepts and installation decisions need another review.

Preparation tips

  • For pipe-material questions, practice locating the relevant specification or plan detail and matching it to the pipe’s installation location.
  • Trace sanitary drainage branches in the direction of flow; note how reductions and abrupt direction changes may affect drainage.
  • Compare hydronic loop layouts and explain how branch balancing, pipe insulation, and air removal influence circulation and heat delivery.
  • Review the purpose of pressure-reducing valves and test shutoff valves for operation and leakage after fixture work.
  • For fuel-burning equipment and rated-wall penetrations, connect the installation detail to combustion safety or preservation of the fire barrier.
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