NC Plumbing, Heating & Fire Sprinkler Contractors
Board – Plumbing Contractor Examination
(Intermediate) Questions and Correct Answers
(Verified Answers) Plus Rationale 2027 Q&A|
Instant Download Pdf
Question 1
What is the primary purpose of a plumbing trap?
A. To increase water pressure
B. To prevent sewer gases from entering a building
C. To increase drainage velocity
D. To prevent water hammer
Answer: B. To prevent sewer gases from entering a building
Rationale: A plumbing trap maintains a water seal between the
drainage system and the occupied space. This water seal prevents
sewer gases and odors from entering the building while still allowing
wastewater to discharge through the fixture drain.
,Question 2
Which type of fitting is normally used to change the direction of a
drainage pipe from horizontal to vertical?
A. Sanitary tee
B. Wye
C. Elbow
D. Coupling
Answer: C. Elbow
Rationale: An elbow is designed to change the direction of piping. In
drainage systems, the specific type and configuration of fitting must be
appropriate for the direction of flow and applicable plumbing
requirements.
Question 3
What is the primary function of a venting system in a sanitary drainage
system?
A. Increase the water pressure
B. Supply hot water to fixtures
C. Protect trap seals and allow proper drainage-system airflow
D. Remove sediment from water heaters
,Answer: C. Protect trap seals and allow proper drainage-system
airflow
Rationale: Drainage vents allow air to enter and leave the drainage
system so pressure changes do not siphon or blow out fixture trap seals.
Proper venting also helps wastewater flow smoothly through the
drainage piping.
Question 4
A water closet is commonly connected to the drainage system using
which type of fitting?
A. Sanitary cross
B. Closet bend
C. Straight coupling
D. Reducing bushing
Answer: B. Closet bend
Rationale: A closet bend is specifically designed to connect a water
closet outlet to the building drainage system while providing the
appropriate change in direction. Its configuration also facilitates proper
connection to the closet flange and drainage piping.
, Question 5
What is the main purpose of a cleanout?
A. To increase water pressure
B. To provide access for cleaning and servicing drainage piping
C. To prevent condensation
D. To reduce hot-water temperature
Answer: B. To provide access for cleaning and servicing drainage
piping
Rationale: Cleanouts provide accessible openings into drainage piping
so obstructions can be removed and the system can be maintained.
They are especially important at locations where changes in direction or
pipe configuration make maintenance more difficult.
Question 6
Which condition is most likely to cause a fixture trap to lose its water
seal through siphonage?
A. Excessive positive pressure in the water supply
B. Improper or inadequate venting
C. Oversized water supply piping
D. Low water temperature
Board – Plumbing Contractor Examination
(Intermediate) Questions and Correct Answers
(Verified Answers) Plus Rationale 2027 Q&A|
Instant Download Pdf
Question 1
What is the primary purpose of a plumbing trap?
A. To increase water pressure
B. To prevent sewer gases from entering a building
C. To increase drainage velocity
D. To prevent water hammer
Answer: B. To prevent sewer gases from entering a building
Rationale: A plumbing trap maintains a water seal between the
drainage system and the occupied space. This water seal prevents
sewer gases and odors from entering the building while still allowing
wastewater to discharge through the fixture drain.
,Question 2
Which type of fitting is normally used to change the direction of a
drainage pipe from horizontal to vertical?
A. Sanitary tee
B. Wye
C. Elbow
D. Coupling
Answer: C. Elbow
Rationale: An elbow is designed to change the direction of piping. In
drainage systems, the specific type and configuration of fitting must be
appropriate for the direction of flow and applicable plumbing
requirements.
Question 3
What is the primary function of a venting system in a sanitary drainage
system?
A. Increase the water pressure
B. Supply hot water to fixtures
C. Protect trap seals and allow proper drainage-system airflow
D. Remove sediment from water heaters
,Answer: C. Protect trap seals and allow proper drainage-system
airflow
Rationale: Drainage vents allow air to enter and leave the drainage
system so pressure changes do not siphon or blow out fixture trap seals.
Proper venting also helps wastewater flow smoothly through the
drainage piping.
Question 4
A water closet is commonly connected to the drainage system using
which type of fitting?
A. Sanitary cross
B. Closet bend
C. Straight coupling
D. Reducing bushing
Answer: B. Closet bend
Rationale: A closet bend is specifically designed to connect a water
closet outlet to the building drainage system while providing the
appropriate change in direction. Its configuration also facilitates proper
connection to the closet flange and drainage piping.
, Question 5
What is the main purpose of a cleanout?
A. To increase water pressure
B. To provide access for cleaning and servicing drainage piping
C. To prevent condensation
D. To reduce hot-water temperature
Answer: B. To provide access for cleaning and servicing drainage
piping
Rationale: Cleanouts provide accessible openings into drainage piping
so obstructions can be removed and the system can be maintained.
They are especially important at locations where changes in direction or
pipe configuration make maintenance more difficult.
Question 6
Which condition is most likely to cause a fixture trap to lose its water
seal through siphonage?
A. Excessive positive pressure in the water supply
B. Improper or inadequate venting
C. Oversized water supply piping
D. Low water temperature
