NL Journeyperson Plumber Certification Exam
Questions And Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
Download Pdf
1. Which of the following is the primary purpose of a trap in a
plumbing system?
a) To increase water pressure
b) To prevent sewer gases from entering the building
c) To allow air into the drainage system
d) To heat water in the pipes
b) To prevent sewer gases from entering the building
Traps create a water seal that blocks sewer gases from traveling back
into occupied spaces.
2. What is the minimum slope for a 2-inch diameter horizontal
drainage pipe?
a) 1/16 inch per foot
b) 1/8 inch per foot
c) 1/4 inch per foot
d) 1/2 inch per foot
c) 1/4 inch per foot
Building codes require a 1/4 inch per foot slope for 2-inch pipes to
ensure proper drainage.
3. Which type of valve is commonly used for controlling water flow to
individual fixtures?
,a) Gate valve
b) Globe valve
c) Ball valve
d) Check valve
c) Ball valve
Ball valves provide quick shut-off and are reliable for controlling water
to fixtures.
4. What is the purpose of a water hammer arrestor?
a) Increase water flow
b) Reduce pressure in the system
c) Prevent pipe vibration and banging
d) Filter sediment from water
c) Prevent pipe vibration and banging
A water hammer arrestor absorbs sudden pressure spikes, preventing
noisy banging in pipes.
5. Which material is commonly used for potable water supply lines in
residential plumbing?
a) PVC
b) CPVC
c) Cast iron
d) Galvanized steel
b) CPVC
CPVC is suitable for hot and cold potable water and meets plumbing
codes in NL.
6. What is the maximum distance a vent can be from the fixture it
serves?
a) 2 feet
,b) 4 feet
c) 6 feet
d) Depends on pipe diameter
d) Depends on pipe diameter
The maximum distance varies by pipe size to ensure proper venting and
prevent siphoning.
7. What type of joint is commonly used for copper tubing in
plumbing?
a) Threaded joint
b) Soldered (sweat) joint
c) Flanged joint
d) Compression joint
b) Soldered (sweat) joint
Copper tubing is typically joined with soldering for a watertight
connection.
8. Which of the following devices prevents backflow into the potable
water system?
a) Gate valve
b) Check valve
c) Ball valve
d) Pressure-reducing valve
b) Check valve
Check valves allow water to flow in one direction only, preventing
contamination.
9. What is the primary reason for insulating hot water pipes?
a) Reduce noise
b) Prevent freezing
, c) Maintain water temperature and reduce energy loss
d) Increase pipe strength
c) Maintain water temperature and reduce energy loss
Insulation reduces heat loss, saving energy and maintaining desired
water temperatures.
10. What is the minimum size of a vent pipe for a 1-1/2 inch drainage
pipe?
a) 1 inch
b) 1-1/4 inch
c) 1-1/2 inch
d) 2 inches
a) 1 inch
The vent size is determined by building code tables to ensure proper
venting for the drain pipe.
11. Which type of pipe is typically used for sanitary sewer drainage in
residential buildings?
a) CPVC
b) PVC
c) PEX
d) Copper
b) PVC
PVC is durable, corrosion-resistant, and suitable for underground
sanitary drainage.
12. What is the main purpose of a pressure-reducing valve?
a) Increase water flow
b) Reduce water pressure to safe levels
c) Control temperature
Questions And Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
Download Pdf
1. Which of the following is the primary purpose of a trap in a
plumbing system?
a) To increase water pressure
b) To prevent sewer gases from entering the building
c) To allow air into the drainage system
d) To heat water in the pipes
b) To prevent sewer gases from entering the building
Traps create a water seal that blocks sewer gases from traveling back
into occupied spaces.
2. What is the minimum slope for a 2-inch diameter horizontal
drainage pipe?
a) 1/16 inch per foot
b) 1/8 inch per foot
c) 1/4 inch per foot
d) 1/2 inch per foot
c) 1/4 inch per foot
Building codes require a 1/4 inch per foot slope for 2-inch pipes to
ensure proper drainage.
3. Which type of valve is commonly used for controlling water flow to
individual fixtures?
,a) Gate valve
b) Globe valve
c) Ball valve
d) Check valve
c) Ball valve
Ball valves provide quick shut-off and are reliable for controlling water
to fixtures.
4. What is the purpose of a water hammer arrestor?
a) Increase water flow
b) Reduce pressure in the system
c) Prevent pipe vibration and banging
d) Filter sediment from water
c) Prevent pipe vibration and banging
A water hammer arrestor absorbs sudden pressure spikes, preventing
noisy banging in pipes.
5. Which material is commonly used for potable water supply lines in
residential plumbing?
a) PVC
b) CPVC
c) Cast iron
d) Galvanized steel
b) CPVC
CPVC is suitable for hot and cold potable water and meets plumbing
codes in NL.
6. What is the maximum distance a vent can be from the fixture it
serves?
a) 2 feet
,b) 4 feet
c) 6 feet
d) Depends on pipe diameter
d) Depends on pipe diameter
The maximum distance varies by pipe size to ensure proper venting and
prevent siphoning.
7. What type of joint is commonly used for copper tubing in
plumbing?
a) Threaded joint
b) Soldered (sweat) joint
c) Flanged joint
d) Compression joint
b) Soldered (sweat) joint
Copper tubing is typically joined with soldering for a watertight
connection.
8. Which of the following devices prevents backflow into the potable
water system?
a) Gate valve
b) Check valve
c) Ball valve
d) Pressure-reducing valve
b) Check valve
Check valves allow water to flow in one direction only, preventing
contamination.
9. What is the primary reason for insulating hot water pipes?
a) Reduce noise
b) Prevent freezing
, c) Maintain water temperature and reduce energy loss
d) Increase pipe strength
c) Maintain water temperature and reduce energy loss
Insulation reduces heat loss, saving energy and maintaining desired
water temperatures.
10. What is the minimum size of a vent pipe for a 1-1/2 inch drainage
pipe?
a) 1 inch
b) 1-1/4 inch
c) 1-1/2 inch
d) 2 inches
a) 1 inch
The vent size is determined by building code tables to ensure proper
venting for the drain pipe.
11. Which type of pipe is typically used for sanitary sewer drainage in
residential buildings?
a) CPVC
b) PVC
c) PEX
d) Copper
b) PVC
PVC is durable, corrosion-resistant, and suitable for underground
sanitary drainage.
12. What is the main purpose of a pressure-reducing valve?
a) Increase water flow
b) Reduce water pressure to safe levels
c) Control temperature
