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Free Practice Questions for CA C-36 Plumbing

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Key Facts: CA C-36 Plumbing Exam

C-36

Contractor Classification

CSLB C-36 classification

3.5 hours

Time Allowance

CSLB examination FAQ

Closed-book

Test Format

CSLB C-36 study guide

$51.43

PSI Exam Registration

PSI C-36 candidate guide; application and license fees separate

At test site

Passing Percentage

CSLB studying for the examination

California C-36 is a plumbing contractor examination. It is closed-book, uses four-choice multiple-choice questions, and allows 3.5 hours. CSLB provides the required passing percentage at the test site; the cited candidate guides do not publish an exact question count.

Sample CA C-36 Plumbing Practice Questions

Try these sample questions to review concepts for the CA C-36 Plumbing exam. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Under the CPC as adopted in California, what is the minimum size drain pipe required for a water closet?
A.2 inches
B.3 inches
C.4 inches
D.1-1/2 inches
Explanation: Per CPC drainage pipe sizing tables, the minimum drain size for a water closet is 3 inches. This applies to all types of water closets and ensures adequate capacity to convey solid waste through the drainage system.
2According to the CPC as enforced in California, what is the minimum slope for a 4-inch horizontal drainage pipe?
A.1/16 inch per foot
B.1/8 inch per foot
C.1/4 inch per foot
D.1/2 inch per foot
Explanation: Per CPC slope requirements, horizontal drainage pipes 3 inches and larger must have a minimum slope of 1/8 inch per foot. Pipes smaller than 3 inches require 1/4 inch per foot. Proper slope ensures self-scouring velocity.
3Under California's plumbing code, what is the DFU value for a residential lavatory?
A.1 DFU
B.2 DFU
C.3 DFU
D.0.5 DFU
Explanation: Per CPC fixture unit tables, a residential lavatory is assigned 1 DFU. This value represents the probable discharge rate and is used to size drainage and venting systems.
4Per the CPC as adopted in California, what is the minimum depth of a fixture trap seal?
A.1 inch
B.2 inches
C.3 inches
D.4 inches
Explanation: Per CPC trap requirements, each fixture trap must have a water seal of not less than 2 inches and not more than 4 inches. The 2-inch minimum prevents sewer gases from passing through under normal conditions.
5According to the CPC as enforced in California, at what intervals must cleanouts be installed on horizontal drainage piping 4 inches and smaller?
A.Every 50 feet
B.Every 75 feet
C.Every 100 feet
D.Every 150 feet
Explanation: Per CPC cleanout requirements, cleanouts must be installed at intervals not exceeding 100 feet for pipes 4 inches and smaller. Additional cleanouts are required at each change of direction greater than 45 degrees.
6Under the CPC as adopted in California, what is the maximum number of DFUs that can be connected to a 3-inch horizontal branch?
A.12 DFU
B.20 DFU
C.36 DFU
D.42 DFU
Explanation: Per CPC drain sizing tables, a 3-inch horizontal branch can serve a maximum of approximately 20 DFU. Exceeding this limit risks drainage backup and surcharging.
7Per the CPC as enforced in California, what is the required slope for a 2-inch horizontal drainage pipe?
A.1/16 inch per foot
B.1/8 inch per foot
C.1/4 inch per foot
D.1/2 inch per foot
Explanation: Per CPC slope requirements, pipes smaller than 3 inches require a minimum slope of 1/4 inch per foot. The steeper slope is necessary for smaller pipes to maintain self-scouring velocity.
8According to the CPC as adopted in California, what is the minimum size building sewer when serving more than one water closet?
A.3 inches
B.4 inches
C.6 inches
D.2 inches
Explanation: Per CPC building sewer requirements, a building sewer serving more than one water closet must be at least 4 inches. A single water closet may use a 3-inch sewer in some configurations.
9Under the CPC as enforced in California, what is the maximum tailpiece length from a fixture outlet to the trap weir?
A.12 inches
B.18 inches
C.24 inches
D.36 inches
Explanation: Per CPC trap requirements, the vertical distance from the fixture outlet to the trap weir must not exceed 24 inches. Longer tailpieces risk siphonage and waste buildup.
10Per the CPC as adopted in California, what is the DFU value for a residential bathtub with shower?
A.1 DFU
B.2 DFU
C.3 DFU
D.4 DFU
Explanation: Per CPC fixture unit tables, a residential bathtub with or without a shower is assigned 2 DFU. The shower head does not add fixture units since it shares the same drain and trap.

About the CA C-36 Plumbing Exam

The C-36 Plumbing examination is the trade examination for California plumbing contractor applicants. CSLB develops the examination and PSI administers it in person. It assesses the planning, installation, repair, and safety knowledge needed by a plumbing contractor. Original applicants generally also take the separate Law and Business examination, subject to CSLB waiver rules.

Exam sponsor: Contractors State License Board (CSLB). The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

Closed-book computer-based multiple choice; four answer choices per question; calculator provided

Time Limit

3.5 hours

Passing Score

Required correct-answer percentage disclosed at the test site

Exam / Certification Fees

$51.43 per C-36 exam registration (PSI); CSLB application and license fees are separate

Exam sponsor website

Fees, eligibility, and exam policies can change. Confirm them with the exam sponsor before applying or paying.

Official sources

Our practice resources: topics covered

We aim to reflect publicly available exam outlines and topic information in our study resources. Coverage, format, and difficulty may differ from the actual exam, and we cannot guarantee that every detail is accurate or current. Confirm exam requirements, fees, and policies with the official exam sponsor.

22%

Planning and Estimating

Project scope, compliance, pipe and vent sizing, plan interpretation, inspections, conservation, coordination, and job costing

22%

Underground and Rough Systems

Excavation, underground work, piping installation and layout, fuel gas systems, insulation, and testing

20%

Finish Plumbing Installations

Fixtures, appliances, water heaters, valves, specialty work, and commercial or industrial piping and sanitary systems

19%

Service, Repair, and Remodel Plumbing Systems

Diagnosing faults, finding damage and leaks, repairs, retrofits, and disposal of removed materials

17%

Safety

Protection of workers, safe job sites, and environmental precautions; CSLB describes blueprint weights as approximate

Preparing for the CA C-36 Plumbing Exam

What You Need to Know

  • Passing score: Required correct-answer percentage disclosed at the test site
  • Assessment: Closed-book computer-based multiple choice; four answer choices per question; calculator provided
  • Time limit: 3.5 hours
  • Exam / certification fees: $51.43 per C-36 exam registration (PSI); CSLB application and license fees are separate Official sources

Using Our Practice Resources

  • Work through all 100 available questions
  • Review every answer and explanation
  • Track weak areas and revisit them
  • Use our AI tutor for tough concepts

CA C-36 Plumbing: Suggested Study Strategy

1Use the five official content areas to organize your preparation, including planning, repair, and safety alongside installation knowledge.
2Practice reading plans and setting up job-cost calculations, checking units before using the calculator.
3Review unfamiliar commercial and specialty plumbing work as well as the systems you encounter regularly.
4Use the current CSLB study guide to choose reference editions and safety resources.
5Practice answering without reference materials and review why each incorrect option fails.

Frequently Asked Questions

Which California plumbing credential does this page cover?

It covers the CSLB C-36 Plumbing Contractor trade examination. Journey-level plumbing experience is part of qualifying for a contractor license; it is not the name of this examination.

How many questions are on the C-36 examination, and what score passes?

The cited CSLB and PSI candidate guides do not publish an exact question count. CSLB states that the required percentage of correct answers is provided at the test site. The time allowance is 3.5 hours.

Can I bring a code book or calculator?

The C-36 examination is closed-book and reference materials are prohibited. A calculator is provided for questions requiring calculations.

Which code edition is listed in the official study guide?

The CSLB C-36 guide revised in March 2026 lists the 2025 California Plumbing Code among its suggested references. It also lists other California construction codes and safety resources. Use the current official guide when selecting study materials.

What experience and education are required?

The qualifying individual must be at least 18 and document four years of qualifying experience in the classification within the last 10 years. No formal education is required. CSLB may credit up to three years of qualifying education or training, with at least one year of practical experience.

What fees are separate from the examination fee?

PSI lists $51.43 per examination registration. CSLB charges a separate $450 original application processing fee and an initial license fee of $200 for a sole owner or $350 for a non-sole owner. Fingerprinting, bond premiums, insurance, and study materials can add costs.

What happens if I fail the examination?

A retake requires a 21-calendar-day wait and a new PSI registration fee. The required examinations must be passed within the application's 18-month eligibility period. After the void date, submit a new application with new fees.