Journeyman Plumbers Plumbing Fixtures and Fittings Questions and Answers — Questions and Answers
Question 1: According to most plumbing codes, what is the maximum vertical distance allowed for a fixture tailpiece, measured from the fixture outlet to the trap weir?
- 12 inches
- 18 inches
- 24 inches (Correct answer)
- 30 inches
Correct answer: 24 inches
Most plumbing codes, including the Uniform Plumbing Code (UPC), limit the vertical length of a fixture tailpiece to 24 inches. This is to prevent self-siphonage of the trap seal due to excessive velocity and momentum of the draining water.
Question 2: A plumber is installing fixtures in a public-use restroom and needs to determine the drainage load. According to the Uniform Plumbing Code (UPC), what is the Drainage Fixture Unit (DFU) value for a public-use lavatory?
- 2.0 (Correct answer)
- 1.0
- 1.5
- 0.5
Correct answer: 2.0
The UPC table for Drainage Fixture Unit Values assigns a DFU of 2.0 for a public-use lavatory, which is higher than the 1.0 DFU for a private lavatory due to more frequent and demanding use. This value is critical for correctly sizing the drainage and vent pipes.
Question 3: To comply with the Americans with Disabilities Act (ADA) standards, what is the maximum height the rim of a lavatory or sink can be mounted above the finished floor?
- 36 inches
- 34 inches (Correct answer)
- 32 inches
- 30 inches
Correct answer: 34 inches
ADA guidelines require that the rim or counter surface of a lavatory or sink be no more than 34 inches above the finished floor to ensure it is accessible to individuals using a wheelchair.
Question 4: A newly installed shower compartment, regardless of its shape, must have a minimum finished interior area and be capable of encompassing a circle of what minimum diameter?
- 24 inches
- 36 inches
- 28 inches
- 30 inches (Correct answer)
Correct answer: 30 inches
Plumbing codes, such as the California Plumbing Code (CPC) and others based on model codes, mandate that a shower compartment must have a minimum finished interior of 1024 square inches and be large enough to contain a 30-inch diameter circle. This ensures adequate space for the user.
Question 5: Which of the following is the most effective and code-approved method for protecting the potable water supply from contamination at a fixture by creating a physical separation?
- Check Valve
- Air Gap (Correct answer)
- Vacuum Breaker
- Air Break
Correct answer: Air Gap
An air gap is the unobstructed vertical space between the water supply outlet and the flood-level rim of a fixture. It is the most reliable and simplest form of backflow prevention because it creates a complete physical separation, preventing any contaminated water from siphoning back into the potable supply.
Question 6: To prevent scalding, most plumbing codes mandate that the hot water supplied to residential bathtubs and showers be limited to a maximum temperature by a temperature-limiting device. What is this maximum temperature?
- 140°F (60°C)
- 110°F (43°C)
- 120°F (49°C) (Correct answer)
- 130°F (54°C)
Correct answer: 120°F (49°C)
To protect users, especially children and the elderly, from severe burns, plumbing codes and safety standards generally require that the maximum temperature of water delivered from fixtures like showers and tubs be limited to 120°F (49°C).
