California Plumbing Contractor (C-36) License Exam Practice Questions And Correct Answers

California Plumbing Contractor (C-36)
License Exam Practice Questions And
Correct Answers

1. What is the minimum slope required for a 3-inch horizontal drain
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pipe?
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• 1/16 inch per foot
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• 1/8 inch per foot
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• 1/4 inch per foot
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• 1/2 inch per foot
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A 3-inch or smaller pipe requires a minimum slope of 1/4 inch per
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foot to maintain proper flow per UPC guidelines.
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2. Which type of valve allows water to flow in one direction only?
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• Gate valve |




• Ball valve
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• Globe valve |

,• Check valve |



A check valve prevents backflow by allowing water to flow in only
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one direction.
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3. What does the “DWV” in plumbing refer to?
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• Drain, Waste, and Vent
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• Down Water Valve | |




• Drain Water Ventilation
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• Direct Waste Valve | |



DWV stands for Drain, Waste, and Vent — the three basic
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components of a residential drainage system.
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4. Which tool is best for threading steel pipe?
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• Tubing cutter |




• Pipe threading machine
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• Pipe bender |




• Reamer
A pipe threading machine is designed to cut threads on steel pipe
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ends for fittings.
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5. The purpose of a trap in a plumbing system is to:
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• Increase water pressure | |




• Prevent sewer gases from entering the building
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• Provide a place to collect sediment
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,• Reduce water velocity | |



Traps use a water seal to block sewer gases from entering the
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structure.
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6. The term “fixture unit” is used to:
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• Determine fire suppression requirements | | |




• Calculate drainage and venting needs| | | |




• Rate fixture quality
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• Size water heaters
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Fixture units are a measure used to calculate the load on a plumbing
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system.
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7. What is the maximum distance between a trap and its vent in a 2-inch
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horizontal drain?
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• 1 foot
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• 2 feet
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• 5 feet
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• 10 feet |



According to the UPC, the maximum trap-to-vent distance for a 2-
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inch pipe is 5 feet.
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8. What type of pipe is most commonly used for residential hot and cold
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water supply?
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• Galvanized steel |




• CPVC

• PEX

, • ABS
PEX is flexible, resistant to corrosion, and commonly used for water
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supply lines.
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9. What is the color code for potable water pipes?
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• Red

• Blue

• Black

• Orange
Blue is typically used to denote potable cold water lines.
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10. Which of the following materials is NOT allowed for gas piping?
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• Black steel |




• Copper (in some jurisdictions)
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• PVC

• CSST
PVC is not approved for gas piping because it is not pressure-rated or
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fire-resistant.
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11. What is the purpose of a cleanout?
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• Reduce pipe pressure | |




• Provide access for clearing clogs
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• Increase pipe diameter | |




• Connect to vent stack | | |



Cleanouts are installed to allow access for drain cleaning equipment.
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