PC Installation Techniques 2 — Questions and Answers
Question 1: When installing a bathtub drain assembly, what is the correct sequence?
- Install overflow plate first, then drain flange
- Install drain flange first, then connect overflow plate (Correct answer)
- Install both simultaneously with a helper
- Sequence does not matter as long as both are sealed
Correct answer: Install drain flange first, then connect overflow plate
The drain flange is installed first into the tub opening, then the overflow plate is connected via the drain linkage to allow the assembly to function properly.
Question 2: What is the minimum slope required per foot for a 4-inch horizontal drain pipe under the International Plumbing Code?
- 1/16 inch per foot
- 1/8 inch per foot (Correct answer)
- 1/4 inch per foot
- 1/2 inch per foot
Correct answer: 1/8 inch per foot
Under the IPC, a 4-inch horizontal drain pipe requires a minimum slope of 1/8 inch per foot (1% grade) to ensure adequate flow.
Question 3: Which fitting is used to transition from cast iron hub-and-spigot pipe to PVC pipe?
- Fernco flexible coupling (Correct answer)
- Dielectric union
- Compression fitting
- Sweat fitting
Correct answer: Fernco flexible coupling
A Fernco (mission coupling) flexible rubber coupling is the standard fitting used to connect dissimilar pipe materials such as cast iron and PVC.
Question 4: When installing PEX tubing through a fire-rated wall assembly, what is required?
- A metal sleeve only
- An intumescent firestop fitting or wrap (Correct answer)
- No special treatment is required
- The tubing must be replaced with copper at the penetration
Correct answer: An intumescent firestop fitting or wrap
PEX penetrations through fire-rated assemblies require intumescent firestop fittings or wraps that expand when heated to seal the opening if the plastic melts.
Question 5: What is the purpose of a vacuum breaker installed on a hose bibb?
- To regulate water pressure at the hose connection
- To prevent backflow from the hose into the potable water supply (Correct answer)
- To allow air into the system to prevent water hammer
- To filter sediment from the water supply
Correct answer: To prevent backflow from the hose into the potable water supply
A hose bibb vacuum breaker prevents backflow by admitting air into the line if negative pressure occurs, protecting the potable water supply from contamination.
Question 6: When installing a pressure-balancing shower valve, what is the primary code requirement for its temperature limit?
- Maximum 100°F (38°C)
- Maximum 110°F (43°C)
- Maximum 120°F (49°C) (Correct answer)
- Maximum 140°F (60°C)
Correct answer: Maximum 120°F (49°C)
ASSE 1016 and plumbing codes require pressure-balancing shower valves to limit hot water delivery to a maximum of 120°F (49°C) to prevent scalding.
Question 7: Which pipe support spacing is correct for 1-inch horizontal copper water supply pipe?
- Every 4 feet
- Every 6 feet (Correct answer)
- Every 8 feet
- Every 10 feet
Correct answer: Every 6 feet
The IPC requires horizontal copper pipe of 1 inch nominal diameter to be supported at maximum 6-foot intervals to prevent sagging and stress on joints.
PC Installation Techniques 2
When installing a bathtub drain assembly, what is the correct sequence?