Texas Tradesman Plumber-Limited
License Practice Exam Questions And
Correct Answers (Verified Answers) Plus
Rationales 2025 Q&A | Instant
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1. What is the minimum diameter pipe allowed for a building sewer?
a) 2 inches
b) 4 inches
c) 3 inches
d) 6 inches
Rationale: A building sewer must be at least 4 inches in diameter per
UPC/IPC standards to ensure proper flow and reduce clogging risk.
2. What is the developed length of a pipe?
a) Vertical measurement
b) Actual length of pipe including fittings
c) Straight-line distance between two points
d) Length before installation
,Rationale: Developed length includes the full measured run of pipe,
accounting for fittings and turns.
3. A plumbing vent must terminate at least how many inches above a
roof?
a) 4 inches
b) 12 inches
c) 6 inches
d) 8 inches
Rationale: Texas plumbing code requires vent terminals to be at least 6
inches above the roof surface to prevent obstruction.
4. What is the minimum horizontal slope required for a 4-inch drain?
a) 1/8 inch per foot
b) 3/8 inch per foot
c) 1/4 inch per foot
d) 1/2 inch per foot
Rationale: A minimum of 1/4 inch per foot is required to maintain flow and
prevent sediment buildup.
5. Which pipe material is typically used for water supply systems?
a) ABS
b) Cast iron
c) Copper
d) Clay
,Rationale: Copper is corrosion-resistant and approved for potable water
supply systems.
6. What device prevents backflow in potable water systems?
a) Air gap
b) Sump
c) Vacuum breaker
d) P-trap
Rationale: Vacuum breakers prevent back siphonage and contamination of
potable water.
7. When must a plumbing permit be obtained?
a) For all plumbing repairs
b) When installing new plumbing systems
c) Only for commercial buildings
d) When replacing fixtures
Rationale: Texas law requires permits for new installations or significant
modifications to plumbing systems.
8. What does the color green on a pipe indicate?
a) Hot water
b) Gas
c) Sewer or drain line
d) Cold water
Rationale: Green is the standard color code for sewage and drain piping.
, 9. What type of pipe joint is used for cast iron pipes?
a) Threaded
b) No-hub coupling
c) Solvent weld
d) Fusion
Rationale: No-hub couplings are common for connecting cast iron pipes
using clamps.
10. What is the minimum water pressure required at a building?
a) 10 psi
b) 20 psi
c) 40 psi
d) 50 psi
Rationale: Minimum water pressure is typically 40 psi to ensure proper
fixture operation.
11. What is the maximum fixture unit load allowed on a 2-inch vent
pipe?
a) 12
b) 16
c) 24
d) 8
Rationale: A 2-inch vent pipe can support up to 24 fixture units per most
code requirements.
License Practice Exam Questions And
Correct Answers (Verified Answers) Plus
Rationales 2025 Q&A | Instant
Download Pdf
1. What is the minimum diameter pipe allowed for a building sewer?
a) 2 inches
b) 4 inches
c) 3 inches
d) 6 inches
Rationale: A building sewer must be at least 4 inches in diameter per
UPC/IPC standards to ensure proper flow and reduce clogging risk.
2. What is the developed length of a pipe?
a) Vertical measurement
b) Actual length of pipe including fittings
c) Straight-line distance between two points
d) Length before installation
,Rationale: Developed length includes the full measured run of pipe,
accounting for fittings and turns.
3. A plumbing vent must terminate at least how many inches above a
roof?
a) 4 inches
b) 12 inches
c) 6 inches
d) 8 inches
Rationale: Texas plumbing code requires vent terminals to be at least 6
inches above the roof surface to prevent obstruction.
4. What is the minimum horizontal slope required for a 4-inch drain?
a) 1/8 inch per foot
b) 3/8 inch per foot
c) 1/4 inch per foot
d) 1/2 inch per foot
Rationale: A minimum of 1/4 inch per foot is required to maintain flow and
prevent sediment buildup.
5. Which pipe material is typically used for water supply systems?
a) ABS
b) Cast iron
c) Copper
d) Clay
,Rationale: Copper is corrosion-resistant and approved for potable water
supply systems.
6. What device prevents backflow in potable water systems?
a) Air gap
b) Sump
c) Vacuum breaker
d) P-trap
Rationale: Vacuum breakers prevent back siphonage and contamination of
potable water.
7. When must a plumbing permit be obtained?
a) For all plumbing repairs
b) When installing new plumbing systems
c) Only for commercial buildings
d) When replacing fixtures
Rationale: Texas law requires permits for new installations or significant
modifications to plumbing systems.
8. What does the color green on a pipe indicate?
a) Hot water
b) Gas
c) Sewer or drain line
d) Cold water
Rationale: Green is the standard color code for sewage and drain piping.
, 9. What type of pipe joint is used for cast iron pipes?
a) Threaded
b) No-hub coupling
c) Solvent weld
d) Fusion
Rationale: No-hub couplings are common for connecting cast iron pipes
using clamps.
10. What is the minimum water pressure required at a building?
a) 10 psi
b) 20 psi
c) 40 psi
d) 50 psi
Rationale: Minimum water pressure is typically 40 psi to ensure proper
fixture operation.
11. What is the maximum fixture unit load allowed on a 2-inch vent
pipe?
a) 12
b) 16
c) 24
d) 8
Rationale: A 2-inch vent pipe can support up to 24 fixture units per most
code requirements.
