Master Plumber Exam Plumbing Codes and Regulations 5 — Questions and Answers
Question 1: Under the IPC, which backflow prevention device provides the highest level of protection for a high-hazard cross-connection?
- Atmospheric vacuum breaker
- Pressure vacuum breaker
- Double check valve assembly
- Reduced pressure zone (RPZ) assembly (Correct answer)
Correct answer: Reduced pressure zone (RPZ) assembly
An RPZ assembly is required for high-hazard connections because it protects against both back-siphonage and back-pressure through a monitored relief port.
Question 2: According to the IPC, potable water supply piping must be separated from drain, waste, and vent piping by at least:
- No specific separation is required as long as there is no cross-connection (Correct answer)
- 6 inches vertically
- 12 inches horizontally
- 18 inches in all directions
Correct answer: No specific separation is required as long as there is no cross-connection
The IPC does not require a specific physical separation distance; it prohibits cross-connections between potable and non-potable systems.
Question 3: A master plumber is sizing a grease interceptor for a restaurant with two 3-compartment sinks. Which standard governs grease interceptor sizing?
- ASME A112.14.3
- PDI G-101 (Correct answer)
- ASSE 1018
- IAPMO PS 23
Correct answer: PDI G-101
PDI G-101 (Plumbing & Drainage Institute) provides the standard sizing method for grease interceptors based on flow rate and retention time.
Question 4: Under model plumbing codes, an approved water heater pressure relief valve must be set to open at or below:
- 100 psi
- 125 psi
- 150 psi (Correct answer)
- 175 psi
Correct answer: 150 psi
Plumbing codes and ASME standards require T&P relief valves on water heaters to open at no more than 150 psi.
Question 5: Per the IPC, what is the minimum diameter of a stack vent or vent stack that serves a building drain handling more than 100 fixture units?
- 2 inches
- 3 inches
- 4 inches (Correct answer)
- 6 inches
Correct answer: 4 inches
IPC vent sizing tables require a minimum 4-inch vent stack when the connected drainage system exceeds 100 DFU.
Question 6: Which of the following code violations would most likely result in a sewer gas odor inside a building?
- Oversized vent pipe
- P-trap installed with the outlet higher than the inlet (Correct answer)
- Vent stack extended 6 inches above the roof
- Horizontal drain sloped at 1/4 inch per foot
Correct answer: P-trap installed with the outlet higher than the inlet
A trap installed backward or sloped so the outlet is higher than the inlet will not retain a water seal, allowing sewer gas to enter.
Question 7: Under the IPC, medical gas systems in healthcare facilities are regulated by which standard?
- IPC Chapter 12
- NFPA 99 (Correct answer)
- ASSE 6010
- ASME B31.3
Correct answer: NFPA 99
NFPA 99, the Health Care Facilities Code, governs the design, installation, and testing of medical gas piping systems.
Master Plumber Exam Plumbing Codes and Regulations 5
Under the IPC, which backflow prevention device provides the highest level of protection for a high-hazard cross-connection?