CSLB C-36 Plumbing Contractor practice questions
200 free questions with answers and explanations.
- 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
- 2.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
- 3.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
- 4.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
- 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
- 6.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
- 7.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
- 8.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
- 9.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
- 10.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
- 11.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
- 12.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?Rough-in Plumbing
- 13.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
- 14.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
- 15.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
- 16.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
- 17.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
- 18.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
- 19.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
- 20.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
- 21.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
- 22.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
- 23.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
- 24.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
- 25.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
- 26.A plumbing contractor is installing a new water supply system for a multi-story commercial building. Which of the following materials is NOT approved for potable water distribution within the building?Rough-in Plumbing
- 27.A plumbing contractor is installing a new residential drain, waste, and vent (DWV) system. What is the minimum required slope for a 4-inch horizontal drainage pipe?Rough-in Plumbing
- 28.A technician is installing a new water heater and notices that the old galvanized steel nipple connecting to the hot water outlet shows significant corrosion where it was previously connected to copper piping. To prevent this issue in the new installation, what component should be used?Service, Repair, and Maintenance
- 29.A plumber is servicing a hydronic heating system and notices that one radiator is significantly colder than the others, despite the boiler operating normally. The system is a two-pipe reverse return system. What is the most likely cause for this specific radiator's issue?Service, Repair, and Maintenance
- 30.A plumbing contractor is installing a new storm drainage system for a commercial building. The system includes a 6-inch diameter storm drain pipe that will be connected to a public storm sewer. What is the maximum allowable depth of water in this 6-inch storm drain pipe when flowing at design capacity, according to good engineering practice and common plumbing code principles?Rough-in Plumbing
- 31.A plumbing contractor is installing a new drain, waste, and vent (DWV) system. A water closet (toilet) is being installed, and its trap arm extends 4 feet horizontally to connect to a 3-inch vertical stack. What is the maximum allowable length for this 3-inch water closet trap arm, according to the California Plumbing Code (CPC)?Rough-in Plumbing
- 32.A client complains that their dishwasher is not draining properly, leaving standing water in the bottom of the tub after a cycle. You've already checked the drain hose for kinks and cleared the food trap. What is the next most probable component to inspect?Service, Repair, and Maintenance
- 33.A technician is called to a residence where the homeowner reports that their clothes dryer is not drying clothes effectively, and there's a strong musty smell coming from the laundry room. Upon inspection, the dryer vent hose appears intact. What is the most likely cause of these symptoms?Service, Repair, and Maintenance
- 34.During a routine commercial plumbing inspection, you notice a constant slight drip from the stem of a gate valve on a main water supply line. The valve is fully open. What is the most appropriate immediate action to address this issue?Service, Repair, and Maintenance
- 35.A plumbing contractor is preparing to backfill a trench containing a newly installed 2-inch copper water service pipe. The trench is located in an area not subject to vehicular traffic. What is the minimum depth of cover required for this water service pipe before backfilling, according to the California Plumbing Code (CPC)?Rough-in Plumbing
- 36.A plumbing inspector is reviewing a rough-in installation for a new gas piping system in a residential garage. The inspector notes that a section of 1-inch diameter black iron gas pipe is unsupported horizontally for a length of 12 feet. According to the UPC, what is the maximum unsupported horizontal length permitted for this pipe size?Rough-in Plumbing
- 37.A homeowner reports that their toilet is flushing weakly, and the bowl does not fully empty, often requiring a second flush. The tank fills normally, and there are no visible clogs in the bowl or drain opening. What is the most likely cause of this issue?Service, Repair, and Maintenance
- 38.A plumbing inspector is reviewing the rough-in for a new multi-story commercial building. The inspector observes a common vent serving two adjacent lavatories, both located on the same floor level. What is the maximum developed length permitted for the common vent from the farthest trap weir to the vent connection?Rough-in Plumbing
- 39.A plumbing inspector is reviewing a new residential gas piping system. The inspector notes that a flexible gas appliance connector, 3 feet in length, is being used to connect a range. The connector is partially concealed within a cabinet wall and extends through a floor. Is this installation compliant with the California Plumbing Code?Rough-in Plumbing
- 40.A client reports that their gas clothes dryer is taking an unusually long time to dry clothes, and the dryer itself feels excessively hot to the touch. The lint trap is regularly cleaned. What is the most likely cause of this issue?Service, Repair, and Maintenance
- 41.A commercial building owner reports a sudden drop in water pressure throughout the entire building. The municipal water supply confirms no issues on their end. What is the most likely cause of this widespread pressure loss?Service, Repair, and Maintenance
- 42.A plumbing contractor is roughing in a new residential DWV system. A 2-inch horizontal wet vent is planned to serve a shower and a lavatory. What is the maximum developed length permitted for this 2-inch horizontal wet vent?Rough-in Plumbing
- 43.A commercial property manager reports that their water bill has significantly increased over the past two months, and they've noticed damp spots on a basement wall that are not associated with any visible leaks from exposed pipes. The building has a copper water supply system. What is the most likely cause of this hidden water loss?Service, Repair, and Maintenance
- 44.A plumber is inspecting a residential sewer cleanout and observes that wastewater containing solids is backing up into the cleanout when the toilets are flushed. However, the kitchen sink and laundry drains are still flowing slowly but not backing up at the same rate. What does this pattern of backup most likely indicate?Service, Repair, and Maintenance
- 45.A plumbing contractor is performing a final inspection of a newly installed residential gas piping system. The system includes a sediment trap (drip leg) installed on the branch line serving a water heater. Where should this sediment trap be located relative to the equipment shut-off valve and the appliance inlet?Rough-in Plumbing
- 46.A plumbing contractor is installing a new drain, waste, and vent (DWV) system in a single-family home. The main building sewer line is being connected to the public sewer lateral at the property line. What is the minimum required slope for this 4-inch building sewer pipe, according to the California Plumbing Code (CPC)?Rough-in Plumbing
- 47.A client notices a faint sulfur or 'rotten egg' smell coming from their hot water only, specifically when using the shower or hot water faucet. The cold water does not have this smell. What is the most likely cause?Service, Repair, and Maintenance
- 48.A client reports that their tankless water heater is producing lukewarm water and occasionally shuts off. The unit has been regularly maintained. Which of the following is the most likely cause of this issue?Service, Repair, and Maintenance
- 49.A plumbing contractor is installing a new underground storm drainage system for a commercial building. The storm drain pipe runs beneath a heavily trafficked parking lot. What is the minimum cover required for a 6-inch storm drain pipe installed in this location?Rough-in Plumbing
- 50.A plumber is installing a new residential drain, waste, and vent (DWV) system. A 3-inch horizontal drain pipe receives discharge from a toilet. What is the minimum required slope for this 3-inch horizontal drain pipe, according to the California Plumbing Code (CPC)?Rough-in Plumbing