PC Plumber Safety & Code Compliance 3 — Questions and Answers
Question 1: Under the IPC, what type of pipe is prohibited from being used for underground installation inside a building for drain, waste, and vent systems?
- PVC Schedule 40
- ABS DWV
- Galvanized steel (Correct answer)
- Cast iron hub-and-spigot
Correct answer: Galvanized steel
Galvanized steel pipe is not approved for underground DWV use inside buildings because it corrodes rapidly when buried and in contact with waste.
Question 2: A permit is required to replace a water heater in most jurisdictions. Which of the following work typically does NOT require a plumbing permit?
- Installing a new bathroom
- Replacing a faucet washer or cartridge (Correct answer)
- Relocating a drain line
- Adding a hose bib to an existing water line
Correct answer: Replacing a faucet washer or cartridge
Minor repairs such as replacing faucet washers or cartridges are maintenance tasks exempt from permit requirements in most plumbing codes.
Question 3: What is the primary purpose of a backflow preventer installed on an irrigation system connected to potable water?
- Regulate water pressure to sprinkler heads
- Prevent contaminated water from flowing back into the drinking supply (Correct answer)
- Reduce water hammer in the irrigation lines
- Ensure equal water distribution across all zones
Correct answer: Prevent contaminated water from flowing back into the drinking supply
Backflow preventers protect the potable water supply from contamination caused by reverse flow from the irrigation system.
Question 4: According to OSHA's lockout/tagout standard (29 CFR 1910.147), before servicing a water heater with hazardous energy, what must a plumber do first?
- Notify building management only
- Isolate all energy sources and verify zero energy state (Correct answer)
- Install a warning sign near the equipment
- Test the equipment once at reduced power
Correct answer: Isolate all energy sources and verify zero energy state
LOTO requires the plumber to isolate all energy sources (gas, electric, water pressure) and verify zero energy state before servicing.
Question 5: The International Plumbing Code requires that all above-ground DWV piping be supported at intervals not exceeding how many feet for 2-inch horizontal PVC pipe?
- 2 feet
- 4 feet (Correct answer)
- 6 feet
- 8 feet
Correct answer: 4 feet
The IPC requires horizontal PVC DWV pipe 2 inches and smaller to be supported at maximum 4-foot intervals to prevent sagging and improper drainage slope.
Question 6: What is the required minimum slope for a 4-inch horizontal drain pipe per the IPC?
- 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
The IPC requires horizontal drain pipes 4 inches and larger to slope at a minimum of 1/8 inch per foot to maintain self-scouring velocity.
Question 7: Which personal protective equipment (PPE) is mandatory when soldering or brazing copper pipe with an open flame torch?
- Hard hat and steel-toed boots only
- Safety glasses and leather gloves (Correct answer)
- Full face shield, hard hat, and earplugs
- Chemical-resistant gloves and apron only
Correct answer: Safety glasses and leather gloves
Safety glasses protect against flux splatter and hot solder, while leather gloves protect against burns from hot pipe and torch flame during soldering.
PC Plumber Safety & Code Compliance 3
Under the IPC, what type of pipe is prohibited from being used for underground installation inside a building for drain, waste, and vent systems?