Nevada Plumbing Contractor Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A Instant Download Pdf
1. What is the minimum water pressure required for residential plumbing
fixtures in Nevada?
A. 15 psi
B. 20 psi
C. 30 psi
D. 40 psi
Answer: 30 psi
Rationale: Residential plumbing fixtures must maintain at least 30 psi to
ensure adequate flow and functionality according to Nevada plumbing
codes.
2. Which pipe material is prohibited for potable water supply?
A. Copper
B. PEX
C. Lead
D. CPVC
Answer: Lead
Rationale: Lead pipes are banned for potable water due to toxicity.
3. What is the minimum slope for a 2-inch horizontal DWV (drain, waste, vent)
pipe?
, A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1/2 inch per foot
D. 1 inch per foot
Answer: 1/4 inch per foot
Rationale: A 1/4 inch per foot slope ensures proper gravity flow in 2-inch
DWV piping.
4. A plumbing contractor must hold which license to install a water heater
commercially?
A. Journeyman plumber
B. Contractor plumber
C. Apprentice plumber
D. HVAC license
Answer: Contractor plumber
Rationale: Installing water heaters commercially requires a licensed
plumbing contractor in Nevada.
5. When testing a new water system, the minimum test pressure for 10
minutes is:
A. 50 psi
B. 75 psi
C. 100 psi
D. 150 psi
Answer: 150 psi
Rationale: Code requires a 150 psi test for a minimum of 10 minutes to
verify integrity of potable water systems.
6. What is the standard thread type for domestic gas connections?
A. NPT
B. NPT (National Pipe Thread)
C. BSP
D. JIC
, Answer: NPT (National Pipe Thread)
Rationale: NPT threads are used in the U.S. for domestic gas piping.
7. Which venting method prevents siphoning of traps?
A. Loop venting
B. Relief venting
C. Wet venting
D. Circuit venting
Answer: Wet venting
Rationale: Wet venting allows one vent to serve multiple fixtures without
trap siphoning.
8. How far can a P-trap be installed from the fixture drain for a lavatory?
A. 12 inches
B. 24 inches
C. 36 inches
D. 48 inches
Answer: 24 inches
Rationale: The Nevada plumbing code limits the trap arm for a lavatory to
24 inches to maintain proper venting and drainage.
9. Which of the following is required for a backflow prevention device?
A. Only in commercial kitchens
B. Where potable water can be contaminated
C. Only for irrigation
D. Only in multi-story buildings
Answer: Where potable water can be contaminated
Rationale: Backflow preventers are mandated wherever cross-
contamination risks exist.
10.What is the maximum water temperature allowed at a residential fixture?
A. 110°F
B. 120°F
C. 125°F
D. 140°F
Practice Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A Instant Download Pdf
1. What is the minimum water pressure required for residential plumbing
fixtures in Nevada?
A. 15 psi
B. 20 psi
C. 30 psi
D. 40 psi
Answer: 30 psi
Rationale: Residential plumbing fixtures must maintain at least 30 psi to
ensure adequate flow and functionality according to Nevada plumbing
codes.
2. Which pipe material is prohibited for potable water supply?
A. Copper
B. PEX
C. Lead
D. CPVC
Answer: Lead
Rationale: Lead pipes are banned for potable water due to toxicity.
3. What is the minimum slope for a 2-inch horizontal DWV (drain, waste, vent)
pipe?
, A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1/2 inch per foot
D. 1 inch per foot
Answer: 1/4 inch per foot
Rationale: A 1/4 inch per foot slope ensures proper gravity flow in 2-inch
DWV piping.
4. A plumbing contractor must hold which license to install a water heater
commercially?
A. Journeyman plumber
B. Contractor plumber
C. Apprentice plumber
D. HVAC license
Answer: Contractor plumber
Rationale: Installing water heaters commercially requires a licensed
plumbing contractor in Nevada.
5. When testing a new water system, the minimum test pressure for 10
minutes is:
A. 50 psi
B. 75 psi
C. 100 psi
D. 150 psi
Answer: 150 psi
Rationale: Code requires a 150 psi test for a minimum of 10 minutes to
verify integrity of potable water systems.
6. What is the standard thread type for domestic gas connections?
A. NPT
B. NPT (National Pipe Thread)
C. BSP
D. JIC
, Answer: NPT (National Pipe Thread)
Rationale: NPT threads are used in the U.S. for domestic gas piping.
7. Which venting method prevents siphoning of traps?
A. Loop venting
B. Relief venting
C. Wet venting
D. Circuit venting
Answer: Wet venting
Rationale: Wet venting allows one vent to serve multiple fixtures without
trap siphoning.
8. How far can a P-trap be installed from the fixture drain for a lavatory?
A. 12 inches
B. 24 inches
C. 36 inches
D. 48 inches
Answer: 24 inches
Rationale: The Nevada plumbing code limits the trap arm for a lavatory to
24 inches to maintain proper venting and drainage.
9. Which of the following is required for a backflow prevention device?
A. Only in commercial kitchens
B. Where potable water can be contaminated
C. Only for irrigation
D. Only in multi-story buildings
Answer: Where potable water can be contaminated
Rationale: Backflow preventers are mandated wherever cross-
contamination risks exist.
10.What is the maximum water temperature allowed at a residential fixture?
A. 110°F
B. 120°F
C. 125°F
D. 140°F
