NEVADA PLUMBING CONTRACTOR EXAMINATION
COMPLETE QUESTIONS AND DETAILED SOLUTIONS
LATEST UPDATE THIS YEAR JUST RELEASED
1. When installing a new sanitary drainage branch serving several
fixtures, what is the primary purpose of maintaining the required slope
throughout the horizontal piping?
A. Increase water pressure at the fixtures
B. Maintain adequate drainage flow and prevent solids from settling
C. Reduce the amount of vent piping required
D. Eliminate the need for cleanouts
Answer: B
Rationale: Proper drainage slope promotes self-scouring flow, helping
wastewater and solids move through the piping without unnecessary
accumulation or blockages.
2. A plumber installs a trap beneath a plumbing fixture in a location
where sewer gases could otherwise enter the occupied building. What
function does this trap primarily provide?
A. Prevent excessive water pressure
B. Store potable drinking water
C. Provide a water seal against sewer gases
D. Increase drainage pipe velocity
Answer: C
,Rationale: The trap retains water that forms a seal, preventing gases
and odors from the drainage system from entering occupied spaces.
3. During installation of a sanitary drainage system, why should a
plumber avoid creating unnecessary sharp directional changes in
horizontal piping?
A. They increase potable water temperature
B. They can restrict flow and increase the likelihood of blockage
C. They eliminate required vent connections
D. They automatically increase pipe diameter
Answer: B
Rationale: Excessive or poorly designed directional changes can impede
drainage flow, promote deposits, and make maintenance more difficult.
4. Which plumbing component is specifically intended to provide access
to drainage piping so that obstructions can be removed during
maintenance?
A. Backflow preventer
B. Cleanout
C. Pressure regulator
D. Vacuum breaker
Answer: B
Rationale: Cleanouts provide accessible openings into drainage piping,
allowing equipment such as drain snakes to reach and clear
obstructions.
,5. A plumbing contractor is determining where a cleanout should be
installed on a long horizontal drainage run. What consideration is most
important?
A. Decorative appearance of the piping
B. Accessibility for future maintenance and cleaning
C. Distance from the nearest electrical outlet
D. Water heater recovery capacity
Answer: B
Rationale: Cleanouts must be positioned where maintenance personnel
can reasonably access them and use appropriate equipment to service
the drainage system.
6. Why is adequate venting necessary in a properly designed sanitary
drainage system serving multiple plumbing fixtures?
A. It increases hot-water temperature
B. It protects trap seals and permits proper drainage airflow
C. It eliminates the need for drainage piping
D. It prevents all fixture leaks
Answer: B
Rationale: Venting balances pressure within drainage piping and helps
prevent siphonage or pressure conditions that could compromise
fixture trap seals.
, 7. A fixture trap repeatedly loses its water seal whenever another
nearby fixture discharges. Which condition should the plumber
investigate first?
A. Insufficient venting or improper vent arrangement
B. Excessive insulation around the fixture
C. Oversized water heater
D. Excessive potable water temperature
Answer: A
Rationale: Repeated trap seal loss associated with nearby drainage
discharge commonly indicates pressure fluctuations caused by
inadequate or improperly configured venting.
8. What is the principal reason plumbing drainage systems are designed
to operate primarily by gravity rather than under pressure?
A. Gravity drainage simplifies flow and reduces pumping requirements
B. Gravity eliminates every possible drainage blockage
C. Gravity automatically disinfects wastewater
D. Gravity increases potable water pressure
Answer: A
Rationale: Properly sloped gravity drainage systems allow wastewater
to move naturally while reducing mechanical complexity and energy
requirements.
9. When connecting drainage piping to a building sewer, what
fundamental objective should the plumber maintain throughout the
installation?
COMPLETE QUESTIONS AND DETAILED SOLUTIONS
LATEST UPDATE THIS YEAR JUST RELEASED
1. When installing a new sanitary drainage branch serving several
fixtures, what is the primary purpose of maintaining the required slope
throughout the horizontal piping?
A. Increase water pressure at the fixtures
B. Maintain adequate drainage flow and prevent solids from settling
C. Reduce the amount of vent piping required
D. Eliminate the need for cleanouts
Answer: B
Rationale: Proper drainage slope promotes self-scouring flow, helping
wastewater and solids move through the piping without unnecessary
accumulation or blockages.
2. A plumber installs a trap beneath a plumbing fixture in a location
where sewer gases could otherwise enter the occupied building. What
function does this trap primarily provide?
A. Prevent excessive water pressure
B. Store potable drinking water
C. Provide a water seal against sewer gases
D. Increase drainage pipe velocity
Answer: C
,Rationale: The trap retains water that forms a seal, preventing gases
and odors from the drainage system from entering occupied spaces.
3. During installation of a sanitary drainage system, why should a
plumber avoid creating unnecessary sharp directional changes in
horizontal piping?
A. They increase potable water temperature
B. They can restrict flow and increase the likelihood of blockage
C. They eliminate required vent connections
D. They automatically increase pipe diameter
Answer: B
Rationale: Excessive or poorly designed directional changes can impede
drainage flow, promote deposits, and make maintenance more difficult.
4. Which plumbing component is specifically intended to provide access
to drainage piping so that obstructions can be removed during
maintenance?
A. Backflow preventer
B. Cleanout
C. Pressure regulator
D. Vacuum breaker
Answer: B
Rationale: Cleanouts provide accessible openings into drainage piping,
allowing equipment such as drain snakes to reach and clear
obstructions.
,5. A plumbing contractor is determining where a cleanout should be
installed on a long horizontal drainage run. What consideration is most
important?
A. Decorative appearance of the piping
B. Accessibility for future maintenance and cleaning
C. Distance from the nearest electrical outlet
D. Water heater recovery capacity
Answer: B
Rationale: Cleanouts must be positioned where maintenance personnel
can reasonably access them and use appropriate equipment to service
the drainage system.
6. Why is adequate venting necessary in a properly designed sanitary
drainage system serving multiple plumbing fixtures?
A. It increases hot-water temperature
B. It protects trap seals and permits proper drainage airflow
C. It eliminates the need for drainage piping
D. It prevents all fixture leaks
Answer: B
Rationale: Venting balances pressure within drainage piping and helps
prevent siphonage or pressure conditions that could compromise
fixture trap seals.
, 7. A fixture trap repeatedly loses its water seal whenever another
nearby fixture discharges. Which condition should the plumber
investigate first?
A. Insufficient venting or improper vent arrangement
B. Excessive insulation around the fixture
C. Oversized water heater
D. Excessive potable water temperature
Answer: A
Rationale: Repeated trap seal loss associated with nearby drainage
discharge commonly indicates pressure fluctuations caused by
inadequate or improperly configured venting.
8. What is the principal reason plumbing drainage systems are designed
to operate primarily by gravity rather than under pressure?
A. Gravity drainage simplifies flow and reduces pumping requirements
B. Gravity eliminates every possible drainage blockage
C. Gravity automatically disinfects wastewater
D. Gravity increases potable water pressure
Answer: A
Rationale: Properly sloped gravity drainage systems allow wastewater
to move naturally while reducing mechanical complexity and energy
requirements.
9. When connecting drainage piping to a building sewer, what
fundamental objective should the plumber maintain throughout the
installation?
