Plumbing Contractor Licensing Examination Questions
and correct detailed answers{verified
answers}|already graded A+
1. Which code is most commonly adopted for plumbing installations in the
United States?
A. NEC
B. IPC
C. IMC
D. NFPA 70
Answer: B. IPC
The International Plumbing Code (IPC) is widely adopted for plumbing systems.
2. The primary purpose of a plumbing vent system is to:
A. Increase water pressure
B. Remove sewage
C. Prevent trap siphonage
D. Supply potable water
Answer: C. Prevent trap siphonage
Vents balance air pressure to protect trap seals.
3. What is the minimum slope for a 3-inch horizontal drainage pipe?
A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1/2 inch per foot
D. Level
Answer: B. 1/4 inch per foot
Standard drainage slope ensures proper flow and self-cleaning.
4. A plumbing contractor is primarily responsible for:
,A. Design approval
B. Code enforcement
C. Installation compliance
D. Material manufacturing
Answer: C. Installation compliance
Contractors must ensure installations meet applicable codes.
5. Which material is approved for potable water supply?
A. ABS
B. PVC DWV
C. PEX
D. Cast iron
Answer: C. PEX
PEX is approved for potable water distribution.
6. Backflow prevention is required to:
A. Increase flow rate
B. Prevent contamination
C. Reduce water bills
D. Improve drainage
Answer: B. Prevent contamination
Backflow devices protect potable water from contamination.
7. Which fitting provides the least resistance to flow?
A. Tee
B. 90° elbow
C. Long-sweep elbow
D. Sanitary tee
Answer: C. Long-sweep elbow
Long sweeps improve flow efficiency in drainage systems.
, 8. What is the minimum trap seal depth?
A. 1 inch
B. 2 inches
C. 4 inches
D. 6 inches
Answer: B. 2 inches
Minimum trap seal depth prevents sewer gas entry.
9. A plumbing permit is typically issued by the:
A. Contractor
B. Property owner
C. Local authority having jurisdiction
D. Supplier
Answer: C. Local authority having jurisdiction
Permits are issued by the local code authority.
10. What device protects against thermal expansion in a closed system?
A. Check valve
B. Pressure regulator
C. Expansion tank
D. Gate valve
Answer: C. Expansion tank
Expansion tanks absorb excess pressure from heated water.
11. Which pipe is most commonly used for sanitary sewers?
A. Copper
B. PEX
C. Cast iron
D. Galvanized steel
Answer: C. Cast iron
Cast iron is durable and sound-dampening for drainage.
and correct detailed answers{verified
answers}|already graded A+
1. Which code is most commonly adopted for plumbing installations in the
United States?
A. NEC
B. IPC
C. IMC
D. NFPA 70
Answer: B. IPC
The International Plumbing Code (IPC) is widely adopted for plumbing systems.
2. The primary purpose of a plumbing vent system is to:
A. Increase water pressure
B. Remove sewage
C. Prevent trap siphonage
D. Supply potable water
Answer: C. Prevent trap siphonage
Vents balance air pressure to protect trap seals.
3. What is the minimum slope for a 3-inch horizontal drainage pipe?
A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1/2 inch per foot
D. Level
Answer: B. 1/4 inch per foot
Standard drainage slope ensures proper flow and self-cleaning.
4. A plumbing contractor is primarily responsible for:
,A. Design approval
B. Code enforcement
C. Installation compliance
D. Material manufacturing
Answer: C. Installation compliance
Contractors must ensure installations meet applicable codes.
5. Which material is approved for potable water supply?
A. ABS
B. PVC DWV
C. PEX
D. Cast iron
Answer: C. PEX
PEX is approved for potable water distribution.
6. Backflow prevention is required to:
A. Increase flow rate
B. Prevent contamination
C. Reduce water bills
D. Improve drainage
Answer: B. Prevent contamination
Backflow devices protect potable water from contamination.
7. Which fitting provides the least resistance to flow?
A. Tee
B. 90° elbow
C. Long-sweep elbow
D. Sanitary tee
Answer: C. Long-sweep elbow
Long sweeps improve flow efficiency in drainage systems.
, 8. What is the minimum trap seal depth?
A. 1 inch
B. 2 inches
C. 4 inches
D. 6 inches
Answer: B. 2 inches
Minimum trap seal depth prevents sewer gas entry.
9. A plumbing permit is typically issued by the:
A. Contractor
B. Property owner
C. Local authority having jurisdiction
D. Supplier
Answer: C. Local authority having jurisdiction
Permits are issued by the local code authority.
10. What device protects against thermal expansion in a closed system?
A. Check valve
B. Pressure regulator
C. Expansion tank
D. Gate valve
Answer: C. Expansion tank
Expansion tanks absorb excess pressure from heated water.
11. Which pipe is most commonly used for sanitary sewers?
A. Copper
B. PEX
C. Cast iron
D. Galvanized steel
Answer: C. Cast iron
Cast iron is durable and sound-dampening for drainage.
