North Carolina (NC) Public Utilities
Contractor Practice Exam –Questions and
Correct Answers (Verified Answers) Plus
Rationales 2025/2026 Q&A
1. What is the primary responsibility of a public utilities contractor?
A. Residential wiring
B. Installation and maintenance of water/sewer systems
C. Landscaping
D. Road paving only
Answer: B
Rationale: Public utilities contractors handle water, sewer, and related infrastructure
systems.
2. What type of permit is typically required before beginning utility work?
A. Electrical permit
B. Building permit
C. Utility construction permit
D. Plumbing permit
Answer: C
Rationale: Utility-specific permits are required for water/sewer installations.
3. What is the purpose of trench shoring?
A. Improve drainage
B. Prevent trench collapse
C. Increase depth
D. Speed excavation
Answer: B
Rationale: Shoring protects workers from cave-ins.
,4. What is the minimum safe oxygen level in a confined space?
A. 15%
B. 19.5%
C. 25%
D. 30%
Answer: B
Rationale: OSHA defines 19.5%–23.5% as safe.
5. Which pipe material is commonly used for water distribution systems?
A. PVC
B. Wood
C. Clay
D. Rubber
Answer: A
Rationale: PVC is widely used due to durability and corrosion resistance.
6. What is the purpose of a backflow preventer?
A. Increase pressure
B. Prevent contamination of water supply
C. Improve drainage
D. Filter debris
Answer: B
Rationale: Prevents contaminated water from reversing flow.
7. What does “invert elevation” refer to?
A. Top of pipe
B. Bottom inside of pipe
C. Ground level
D. Pipe thickness
, Answer: B
Rationale: Critical for gravity sewer design.
8. What is the most common cause of trench collapse?
A. Wind
B. Water infiltration
C. Vibration
D. Soil instability
Answer: D
Rationale: Unstable soil is the primary hazard.
9. Which system relies on gravity flow?
A. Pressurized water system
B. Sanitary sewer system
C. Electrical system
D. Gas system
Answer: B
Rationale: Sewers rely on slope for flow.
10. What is the purpose of bedding in pipe installation?
A. Protect pipe and provide support
B. Increase flow
C. Reduce cost
D. Improve pressure
Answer: A
Rationale: Bedding stabilizes and protects pipes.
11. What does OSHA require for trenches deeper than 5 feet?
A. Painting
B. Protective systems
Contractor Practice Exam –Questions and
Correct Answers (Verified Answers) Plus
Rationales 2025/2026 Q&A
1. What is the primary responsibility of a public utilities contractor?
A. Residential wiring
B. Installation and maintenance of water/sewer systems
C. Landscaping
D. Road paving only
Answer: B
Rationale: Public utilities contractors handle water, sewer, and related infrastructure
systems.
2. What type of permit is typically required before beginning utility work?
A. Electrical permit
B. Building permit
C. Utility construction permit
D. Plumbing permit
Answer: C
Rationale: Utility-specific permits are required for water/sewer installations.
3. What is the purpose of trench shoring?
A. Improve drainage
B. Prevent trench collapse
C. Increase depth
D. Speed excavation
Answer: B
Rationale: Shoring protects workers from cave-ins.
,4. What is the minimum safe oxygen level in a confined space?
A. 15%
B. 19.5%
C. 25%
D. 30%
Answer: B
Rationale: OSHA defines 19.5%–23.5% as safe.
5. Which pipe material is commonly used for water distribution systems?
A. PVC
B. Wood
C. Clay
D. Rubber
Answer: A
Rationale: PVC is widely used due to durability and corrosion resistance.
6. What is the purpose of a backflow preventer?
A. Increase pressure
B. Prevent contamination of water supply
C. Improve drainage
D. Filter debris
Answer: B
Rationale: Prevents contaminated water from reversing flow.
7. What does “invert elevation” refer to?
A. Top of pipe
B. Bottom inside of pipe
C. Ground level
D. Pipe thickness
, Answer: B
Rationale: Critical for gravity sewer design.
8. What is the most common cause of trench collapse?
A. Wind
B. Water infiltration
C. Vibration
D. Soil instability
Answer: D
Rationale: Unstable soil is the primary hazard.
9. Which system relies on gravity flow?
A. Pressurized water system
B. Sanitary sewer system
C. Electrical system
D. Gas system
Answer: B
Rationale: Sewers rely on slope for flow.
10. What is the purpose of bedding in pipe installation?
A. Protect pipe and provide support
B. Increase flow
C. Reduce cost
D. Improve pressure
Answer: A
Rationale: Bedding stabilizes and protects pipes.
11. What does OSHA require for trenches deeper than 5 feet?
A. Painting
B. Protective systems
