CT Limited Plumbing Journeyperson (P-
4) Exam – State Of Connecticut
Questions And Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A |
Instant Download Pdf
Question 1
What is the primary purpose of a plumbing vent system?
A. Increase water pressure
B. Prevent sewer gases from entering the building
C. Speed up drainage flow
D. Reduce pipe corrosion
B. Prevent sewer gases from entering the building
Rationale: The vent system in plumbing is designed to maintain atmospheric
pressure within the drainage system and safely direct sewer gases out through
the roof. Without proper venting, trap seals could be siphoned or blown out,
allowing hazardous gases such as methane and hydrogen sulfide to enter the
building. Vents also ensure smooth drainage by balancing pressure in the
system.
Question 2
Which tool is commonly used to cut copper tubing?
A. Pipe wrench
B. Tubing cutter
,C. Hacksaw
D. Basin wrench
B. Tubing cutter
Rationale: A tubing cutter is specifically designed to produce clean, square cuts
on copper tubing without deforming the pipe. While a hacksaw can be used, it
often leaves rough edges that require deburring. Proper cutting ensures tight
soldered joints and prevents leaks.
Question 3
What is the minimum slope required for a 3-inch horizontal drain pipe?
A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1 inch per foot
D. Level installation
B. 1/4 inch per foot
Rationale: Plumbing codes typically require a minimum slope of 1/4 inch per
foot for pipes 3 inches and smaller to ensure proper gravity flow and prevent
solids from settling. Larger pipes may allow 1/8 inch per foot, but 3-inch piping
still generally requires 1/4 inch per foot for effective drainage.
Question 4
Which material is most commonly used for DWV systems in modern residential
construction?
A. Lead
B. Cast iron
C. PVC
D. Galvanized steel
C. PVC
Rationale: PVC (polyvinyl chloride) is widely used in DWV systems due to its low
,cost, corrosion resistance, ease of installation, and smooth interior surface that
promotes efficient flow. Cast iron is still used in some commercial applications
but is heavier and more expensive.
Question 5
What is the function of a P-trap?
A. Increase water pressure
B. Prevent sewer gas entry
C. Filter debris from water supply
D. Regulate pipe temperature
B. Prevent sewer gas entry
Rationale: A P-trap holds a water seal that blocks sewer gases from entering the
building through fixtures. The curved shape retains water even when the fixture
is not in use, maintaining a barrier between the drain system and occupied
spaces.
Question 6
What is water hammer?
A. Slow drainage
B. Pipe freezing
C. Pressure surge caused by sudden valve closure
D. Pipe corrosion
C. Pressure surge caused by sudden valve closure
Rationale: Water hammer occurs when flowing water is suddenly stopped,
creating a shockwave in the piping system. This can damage pipes, fittings, and
fixtures. Air chambers or arrestors are used to reduce this effect.
Question 7
, Which fitting changes pipe direction by 90 degrees?
A. Tee
B. Coupling
C. Elbow
D. Reducer
C. Elbow
Rationale: An elbow fitting is specifically designed to change the direction of
piping, commonly at 45° or 90° angles. It is essential in routing piping systems
around obstacles and maintaining proper alignment.
Question 8
Which of the following is a potable water pipe material?
A. ABS
B. PVC sewer pipe
C. Copper Type L
D. Orange drain tile
C. Copper Type L
Rationale: Copper Type L is commonly approved for potable water systems due
to its durability, corrosion resistance, and safety for drinking water. PVC used for
drainage is not always rated for potable use unless specifically marked.
Question 9
What is the purpose of a cleanout in a drainage system?
A. Increase flow rate
B. Provide access for clearing blockages
C. Reduce pipe size
D. Increase venting capacity
B. Provide access for clearing blockages
Rationale: Cleanouts allow plumbers to access the interior of drainage pipes for
4) Exam – State Of Connecticut
Questions And Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A |
Instant Download Pdf
Question 1
What is the primary purpose of a plumbing vent system?
A. Increase water pressure
B. Prevent sewer gases from entering the building
C. Speed up drainage flow
D. Reduce pipe corrosion
B. Prevent sewer gases from entering the building
Rationale: The vent system in plumbing is designed to maintain atmospheric
pressure within the drainage system and safely direct sewer gases out through
the roof. Without proper venting, trap seals could be siphoned or blown out,
allowing hazardous gases such as methane and hydrogen sulfide to enter the
building. Vents also ensure smooth drainage by balancing pressure in the
system.
Question 2
Which tool is commonly used to cut copper tubing?
A. Pipe wrench
B. Tubing cutter
,C. Hacksaw
D. Basin wrench
B. Tubing cutter
Rationale: A tubing cutter is specifically designed to produce clean, square cuts
on copper tubing without deforming the pipe. While a hacksaw can be used, it
often leaves rough edges that require deburring. Proper cutting ensures tight
soldered joints and prevents leaks.
Question 3
What is the minimum slope required for a 3-inch horizontal drain pipe?
A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1 inch per foot
D. Level installation
B. 1/4 inch per foot
Rationale: Plumbing codes typically require a minimum slope of 1/4 inch per
foot for pipes 3 inches and smaller to ensure proper gravity flow and prevent
solids from settling. Larger pipes may allow 1/8 inch per foot, but 3-inch piping
still generally requires 1/4 inch per foot for effective drainage.
Question 4
Which material is most commonly used for DWV systems in modern residential
construction?
A. Lead
B. Cast iron
C. PVC
D. Galvanized steel
C. PVC
Rationale: PVC (polyvinyl chloride) is widely used in DWV systems due to its low
,cost, corrosion resistance, ease of installation, and smooth interior surface that
promotes efficient flow. Cast iron is still used in some commercial applications
but is heavier and more expensive.
Question 5
What is the function of a P-trap?
A. Increase water pressure
B. Prevent sewer gas entry
C. Filter debris from water supply
D. Regulate pipe temperature
B. Prevent sewer gas entry
Rationale: A P-trap holds a water seal that blocks sewer gases from entering the
building through fixtures. The curved shape retains water even when the fixture
is not in use, maintaining a barrier between the drain system and occupied
spaces.
Question 6
What is water hammer?
A. Slow drainage
B. Pipe freezing
C. Pressure surge caused by sudden valve closure
D. Pipe corrosion
C. Pressure surge caused by sudden valve closure
Rationale: Water hammer occurs when flowing water is suddenly stopped,
creating a shockwave in the piping system. This can damage pipes, fittings, and
fixtures. Air chambers or arrestors are used to reduce this effect.
Question 7
, Which fitting changes pipe direction by 90 degrees?
A. Tee
B. Coupling
C. Elbow
D. Reducer
C. Elbow
Rationale: An elbow fitting is specifically designed to change the direction of
piping, commonly at 45° or 90° angles. It is essential in routing piping systems
around obstacles and maintaining proper alignment.
Question 8
Which of the following is a potable water pipe material?
A. ABS
B. PVC sewer pipe
C. Copper Type L
D. Orange drain tile
C. Copper Type L
Rationale: Copper Type L is commonly approved for potable water systems due
to its durability, corrosion resistance, and safety for drinking water. PVC used for
drainage is not always rated for potable use unless specifically marked.
Question 9
What is the purpose of a cleanout in a drainage system?
A. Increase flow rate
B. Provide access for clearing blockages
C. Reduce pipe size
D. Increase venting capacity
B. Provide access for clearing blockages
Rationale: Cleanouts allow plumbers to access the interior of drainage pipes for
