1. A plumbing inspector is reviewing a rough-in for a new multi-story residential building. The inspector observes a common vent serving two fixture traps. What is the maximum developed length of the common vent, measured from the farthest trap arm to the vent stack, before it requires an additional vent or different venting method, assuming 1 1/2-inch pipe size?
Rough-in Plumbing
A.8 feet
B.15 feet
C.12 feet
D.10 feet
Show answerAnswer
D. 10 feet
The California Plumbing Code (CPC) limits the developed length of a common vent based on its size. For a 1 1/2-inch common vent, the maximum developed length from the farthest trap weir to the vent stack or branch vent connection is 10 feet to ensure adequate air circulation and prevent siphonage.
2. A plumbing contractor is preparing to backfill a trench containing a newly installed underground water supply pipe. What is the minimum depth of cover required for underground potable water piping outside of a building, when not located under a slab or driveway?
Rough-in Plumbing
A.24 inches
B.12 inches
C.6 inches
D.18 inches
Show answerAnswer
B. 12 inches
The California Plumbing Code (CPC) requires a minimum of 12 inches of cover for underground potable water piping outside of a building, unless it is located under a slab or driveway where it may be less, or in areas subject to vehicular traffic which typically requires more cover.
3. A plumbing inspector is reviewing the rough-in for a new residential DWV system. The inspector notes that a horizontal wet vent serves a lavatory and a shower. What is the maximum developed length permitted for the wet vent from the furthest fixture trap weir to the vent stack or stack vent?
Rough-in Plumbing
A.12 feet
B.8 feet
C.6 feet
D.10 feet
Show answerAnswer
C. 6 feet
The California Plumbing Code (CPC) limits the developed length of horizontal wet vents to prevent excessive pressure fluctuations and ensure proper venting. For a 2-inch wet vent (typical for lavatory and shower), the maximum developed length is 6 feet from the furthest trap weir to the connection to a vent stack or stack vent.
4. A plumbing contractor is installing a new storm drainage system for a commercial building. The system includes several roof drains connected to a common horizontal storm drain. What is the minimum size of a horizontal storm drain pipe that serves a roof area of 1,000 square feet with a maximum rainfall rate of 4 inches per hour?
Rough-in Plumbing
A.4 inches
B.3 inches
C.6 inches
D.5 inches
Show answerAnswer
A. 4 inches
To size a horizontal storm drain, the CPC references tables based on rainfall rate and drained area. For a rainfall rate of 4 inches per hour, a 1,000 sq ft area requires a minimum 4-inch pipe. (Calculation: CPC Table 1101.8, 4" rainfall rate, 1000 sq ft, shows 4" pipe for up to 1200 sq ft).
5. A plumber is preparing to conduct an air test on a new DWV system rough-in. The system consists of 3-inch PVC piping. What is the minimum air pressure that must be maintained in the system for at least 15 minutes during the test?
Rough-in Plumbing
A.3 psi
B.2 psi
C.5 psi
D.10 psi
Show answerAnswer
C. 5 psi
According to the California Plumbing Code (CPC), DWV systems tested with air must be subjected to a minimum pressure of 5 psi for at least 15 minutes. This pressure is sufficient to detect leaks without overstressing the piping system.
6. A plumbing contractor is roughing in a new gas piping system for a commercial building. The system uses Schedule 40 black steel pipe. What is the maximum allowable length of an unthreaded (plain end) steel pipe nipple that can be used in the system without requiring special engineering or approval?
Rough-in Plumbing
A.3 inches
B.6 inches
C.8 inches
D.12 inches
Show answerAnswer
B. 6 inches
According to the California Plumbing Code (CPC), unthreaded gas pipe nipples should generally not exceed 6 inches in length. Longer nipples can be more prone to damage or bending, especially in an unthreaded configuration, unless specifically engineered and approved.
7. A plumbing contractor is installing a new residential drain, waste, and vent (DWV) system. For a 4-inch horizontal drain pipe, what is the minimum required slope per foot to ensure proper drainage?
Rough-in Plumbing
A.1/8 inch per foot
B.1/2 inch per foot
C.1/16 inch per foot
D.1/4 inch per foot
Show answerAnswer
D. 1/4 inch per foot
The California Plumbing Code (CPC) specifies minimum slopes for horizontal drainage piping. For pipes 2-1/2 inches or larger, the minimum slope is 1/4 inch per foot.
8. A plumber is installing a new underground storm drainage system for a commercial building. The system includes a 6-inch diameter PVC pipe. What is the minimum required cover for this pipe under a landscape area not subject to vehicular traffic?
Rough-in Plumbing
A.24 inches
B.6 inches
C.12 inches
D.18 inches
Show answerAnswer
C. 12 inches
According to the California Plumbing Code (CPC), underground drainage piping not subject to vehicular traffic, such as in a landscape area, must have a minimum cover of 12 inches. This protects the pipe from damage due to routine ground disturbances.
9. A plumbing inspector notes that a relief valve discharge pipe from a water heater is terminated directly into a floor drain. What is the primary reason this installation violates the California Plumbing Code (CPC)?
Rough-in Plumbing
A.The discharge pipe must be insulated.
B.The discharge pipe must terminate with an air gap.
C.The discharge pipe must be larger than the relief valve outlet.
D.The discharge pipe must be made of copper or galvanized steel.
Show answerAnswer
B. The discharge pipe must terminate with an air gap.
The California Plumbing Code (CPC) mandates that the discharge pipe from a temperature and pressure (T&P) relief valve must terminate with an air gap. This prevents potential back-siphonage of contaminated water from the drain into the potable water system through the relief valve, protecting the water supply from contamination.
10. A plumbing contractor is conducting an inspection of an existing DWV system. The contractor notices that a vent terminal is located too close to an operable window. According to the California Plumbing Code (CPC), what is the minimum horizontal distance required between a vent terminal and an operable window, door, or other opening into a building?
Rough-in Plumbing
A.3 feet
B.10 feet
C.1 foot
D.5 feet
Show answerAnswer
B. 10 feet
To prevent foul odors and potentially harmful gases from entering a building, the California Plumbing Code (CPC) requires a minimum horizontal distance of 10 feet between a vent terminal and any operable window, door, or other opening into the building.
11. A plumbing contractor is installing a new residential DWV system. A 3-inch horizontal drain pipe transitions to a 3-inch vertical stack. What is the maximum permissible angle for a fitting connecting a horizontal drain to a vertical stack to be considered a 'stack fitting' for DWV purposes?
Rough-in Plumbing
A.60 degrees (1/6 bend)
B.22.5 degrees (1/16 bend)
C.45 degrees (1/8 bend)
D.90 degrees (1/4 bend)
Show answerAnswer
C. 45 degrees (1/8 bend)
The California Plumbing Code (CPC) specifies that horizontal drainage pipes connecting to vertical stacks must do so with fittings that allow for a smooth transition to prevent flow impedance and turbulence. A 45-degree (1/8 bend) fitting is the maximum permissible angle for a horizontal drain to enter a vertical stack without requiring additional consideration for flow dynamics, although smoother transitions with lesser angles are also permitted.
12. A plumbing contractor is installing an underground drain pipe that will pass through a concrete foundation wall. What type of sleeve is required around the pipe where it penetrates the foundation, according to CPC?
Rough-in Plumbing
A.A foam insulation sleeve
B.A tightly fitted metal sleeve
C.No sleeve is required if the concrete is poured carefully
D.A loosely fitted, non-corrosive sleeve
Show answerAnswer
D. A loosely fitted, non-corrosive sleeve
The California Plumbing Code (CPC) requires that pipes passing through or under concrete foundation walls be protected by a loosely fitted, non-corrosive sleeve. This prevents damage to the pipe from building settlement or expansion/contraction of the concrete, and allows for minor movement.
13. A plumbing contractor is installing a new water supply system for a multi-story commercial building. Which of the following materials is generally NOT permitted for potable water distribution piping within the building according to current California Plumbing Code (CPC) standards?
Rough-in Plumbing
A.Copper tubing (Type L or K)
B.Galvanized steel pipe
C.CPVC pipe
D.PEX tubing
Show answerAnswer
B. Galvanized steel pipe
While historically used, galvanized steel pipe is generally not permitted for new potable water distribution systems in California due to corrosion issues, which can lead to reduced flow and water quality problems over time. The CPC has largely phased it out for new installations.
14. A plumbing contractor is installing a new water supply system for a single-family dwelling. The water service pipe is run horizontally under the front yard. What is the minimum required distance the water service pipe must be from a parallel building sewer pipe?
Rough-in Plumbing
A.24 inches
B.6 inches
C.12 inches
D.18 inches
Show answerAnswer
C. 12 inches
To prevent potential contamination, the California Plumbing Code (CPC) requires that a water service pipe be installed at least 12 inches horizontally from any parallel building sewer or drainage pipe. This separation helps safeguard potable water quality.
15. A plumbing contractor is installing a backflow prevention device on a potable water supply line to an irrigation system. Which type of backflow preventer is typically required for this high-hazard application where there is a constant pressure condition and potential for back-siphonage and backpressure?
C. Reduced Pressure Principle Backflow Assembly (RPBA)
For high-hazard applications like irrigation systems with constant pressure, the Reduced Pressure Principle Backflow Assembly (RPBA) is typically required. It provides the highest level of protection against both back-siphonage and backpressure by incorporating a relief valve that opens to atmosphere when pressure differentials are compromised.
16. A plumbing contractor is installing a new residential gas piping system. The exposed portion of the gas piping outside the building is made of black steel pipe. What is the required protective coating or treatment for this exposed piping?
Rough-in Plumbing
A.Galvanized finish or approved corrosion-resistant coating
B.No coating is required if it's Schedule 40 steel
C.A mastic coating and fabric wrap
D.A layer of epoxy paint
Show answerAnswer
A. Galvanized finish or approved corrosion-resistant coating
The California Plumbing Code (CPC) requires that exposed portions of gas piping that are subject to corrosion (such as black steel pipe outdoors) must be protected by a galvanized finish or an approved corrosion-resistant coating. This prevents oxidation and degradation of the pipe over time.
17. A plumbing inspector is reviewing a rough-in installation for a new gas piping system in a commercial kitchen. The inspector observes that the gas piping is run through a concrete slab. What specific protection is required for gas piping installed within a concrete slab?
Rough-in Plumbing
A.No special protection is required if the pipe is Schedule 40 steel.
B.The pipe must be painted with a corrosion-resistant coating.
C.The pipe must be wrapped with approved electrical tape.
D.The pipe must be encased in a continuous sleeve or conduit.
Show answerAnswer
D. The pipe must be encased in a continuous sleeve or conduit.
Gas piping installed in or under a concrete slab must be protected from corrosion and damage. The California Plumbing Code (CPC) mandates that such piping be encased in a continuous, approved sleeve or conduit that extends through the slab and is sealed at the ends to prevent water or concrete from contacting the pipe.
18. A plumbing contractor is roughing in a new residential drain, waste, and vent (DWV) system. What is the minimum required slope for a 3-inch horizontal drain pipe serving a water closet?
Rough-in Plumbing
A.1/4 inch per foot
B.1/2 inch per foot
C.1/16 inch per foot
D.1/8 inch per foot
Show answerAnswer
A. 1/4 inch per foot
The California Plumbing Code (CPC) specifies minimum slopes for horizontal drainage piping. For pipes 3 inches or larger, the minimum slope is 1/4 inch per foot to ensure proper drainage and prevent clogging.
19. A plumbing contractor is installing a new residential water supply system. A water hammer arrestor is required for a quick-closing valve on a washing machine connection. What is the minimum approved type of water hammer arrestor that should be installed?
Rough-in Plumbing
A.Any type listed in the CPC as an approved device
B.A permanently sealed air chamber type
C.A piston-type with an air chamber
D.A spring-loaded accumulator type
Show answerAnswer
A. Any type listed in the CPC as an approved device
The California Plumbing Code (CPC) does not specify a single 'minimum approved type' of water hammer arrestor beyond requiring that it be a listed and approved device. Various types (piston, bellows, permanently charged air chambers, etc.) are acceptable as long as they meet the performance standards of the applicable listing (e.g., ASSE 1010) and are approved for use.
20. A plumber is installing a new residential drain, waste, and vent (DWV) system. A water closet (toilet) is being installed on the ground floor. What is the minimum required size for the trap arm connecting the water closet to the main horizontal drain?
Rough-in Plumbing
A.3 inches
B.2 inches
C.1.5 inches
D.4 inches
Show answerAnswer
A. 3 inches
The California Plumbing Code (CPC) mandates specific pipe sizes for fixtures. A water closet (toilet) requires a minimum 3-inch trap and trap arm to ensure proper waste removal and prevent clogging.
21. A plumbing contractor is installing a new water heater in a residential garage. The water heater is gas-fired. What is the minimum required height above the igniter for the vent termination, measured from the highest point where the vent passes through the roof?
Rough-in Plumbing
A.12 inches
B.6 inches
C.24 inches
D.18 inches
Show answerAnswer
A. 12 inches
According to the California Plumbing Code (CPC), the vent for a gas appliance must terminate at least 12 inches above the highest point where it passes through the roof to ensure proper draft and dispersion of combustion byproducts.
22. A plumber is performing a final pressure test on a newly installed potable water supply system. The system is to be tested with air. According to the California Plumbing Code (CPC), what is the minimum air pressure that the system must be subjected to, and for what minimum duration?
Rough-in Plumbing
A.100 psi for 15 minutes
B.50 psi for 15 minutes
C.80 psi for 30 minutes
D.125 psi for 30 minutes
Show answerAnswer
B. 50 psi for 15 minutes
For potable water supply systems, the California Plumbing Code (CPC) allows for testing with air pressure. The minimum requirement is 50 psi, maintained for at least 15 minutes, with no perceptible loss of pressure.
23. A plumbing contractor is installing a new residential gas piping system using Corrugated Stainless Steel Tubing (CSST). What specific protective requirement applies when CSST is installed in concealed locations, such as within wall cavities or attics, to prevent damage from nails or screws?
Rough-in Plumbing
A.No special protection is required if the CSST is installed according to manufacturer's instructions.
B.The CSST must be painted with a high-visibility color for inspection.
C.The CSST must be sleeved in PVC conduit when passing through studs.
D.Steel strike plates or shields must be installed on the studs or joists where the CSST passes within 1.5 inches of the edge.
Show answerAnswer
D. Steel strike plates or shields must be installed on the studs or joists where the CSST passes within 1.5 inches of the edge.
To protect CSST from puncture by nails or screws in concealed locations, the California Plumbing Code (CPC) requires the installation of steel strike plates or shields on wood framing members where the tubing is within 1.5 inches of the framing edge. This is similar to electrical wiring protection.
24. A plumbing contractor is installing a new residential gas piping system. The gas line passes through a concrete foundation wall. To prevent damage to the pipe, what is the minimum annular space required around the gas pipe where it passes through the sleeve in the foundation wall, according to the California Plumbing Code (CPC)?
Rough-in Plumbing
A.1/2 inch
B.1 inch
C.1/4 inch
D.2 inches
Show answerAnswer
A. 1/2 inch
When gas piping passes through a foundation or structural wall, a sleeve is required to protect the pipe. The California Plumbing Code mandates a minimum 1/2-inch annular space between the pipe and the sleeve to allow for movement and prevent corrosion.
25. A client reports that their basement floor drain is backing up with sudsy water whenever the washing machine discharges, but the toilets and other drains in the house function normally. What is the most likely cause?
Service, Repair, and Maintenance
A.A broken or collapsed sewer line under the foundation.
B.A blockage in the main sewer line downstream of all fixtures.
C.A partially clogged branch line specific to the laundry drain.
D.A clogged plumbing vent for the basement fixtures.
Show answerAnswer
C. A partially clogged branch line specific to the laundry drain.
If only the basement floor drain backs up when the washing machine discharges, but other fixtures are fine, it indicates a localized blockage. The most likely culprit is a partial clog in the branch line serving the laundry area, which is too small to handle the washing machine's high-volume discharge. The sudsy water confirms it's laundry waste.
The total length of a common vent pipe, measured along the centerline of the pipe and fittings from the farthest trap weir to the vent stack or branch vent connection.
Ensures proper air circulation for multiple fixtures.
Prevents trap seal loss due to siphonage or backpressure.
Length limits are specified by plumbing codes based on pipe size.
The maximum permissible developed length of a horizontal wet vent pipe from the furthest fixture trap weir to its connection to a dry vent or stack vent.
Prevents trap siphonage or backpressure.
Length limits vary by pipe size and fixture units.
Ensures adequate air circulation in the DWV system.
A short piece of pipe, often threaded on both ends, used to connect other fittings or pipes in a gas system. Unthreaded nipples have specific length limitations.
Used for short connections.
Threaded nipples are common; unthreaded are less so in gas.
Length limits prevent excessive leverage or stress on connections.
The safe and visible termination of the pipe carrying hot water from a water heater's temperature and pressure relief valve, designed to prevent scalding and system overpressure.
Prevents building of dangerous pressure/temperature.
The method and maximum angle of fittings used to connect a horizontal drainage pipe to a vertical drainage stack, critical for maintaining proper flow and preventing blockages.
Ensures smooth wastewater flow.
Prevents turbulence and blockages.
Specific fitting types and angles are code-mandated.
A protective conduit installed around a pipe where it passes through a structural element like a foundation wall, to prevent damage and allow for movement.
Protects pipes from crushing or shearing forces.
Accommodates building settlement and thermal expansion/contraction.
Mandated by plumbing codes for structural penetrations.
Requirement for steel plates or shields to protect Corrugated Stainless Steel Tubing (CSST) from puncture by nails or screws in concealed wall or ceiling cavities.
Mandatory for CSST in concealed spaces.
Protects against damage from building fasteners.
Required when CSST is near framing edges (1.5 inches).
The minimum clear distance required between a gas pipe and its protective sleeve when passing through a structural element, allowing for movement and preventing damage.
Questions are original practice items written to match the published exam objectives. Step2Study is not affiliated with or endorsed by any certification body.