California C-36 Plumbing Contractor (C-36) Practice Test 2026 - Free Diagnostic

Introduction

The California C-36 Plumbing Contractor license exam is a 115-question, closed-book test administered by PSI Services on behalf of the Contractors State License Board (CSLB). You have 3 hours and 30 minutes to complete it and need a score of 72% or higher to pass — 83 correct answers out of 115. The exam covers five topic areas drawn from the CSLB content outline: Planning and Estimating and Underground and Rough Systems are the two largest sections at 22% each, followed by Finish Plumbing Installations at 20%, Service, Repair and Remodel at 19%, and Safety at 17%. Unlike the ICC inspector exams, the C-36 is a contractor trade exam — it tests practical installation knowledge, job site safety, and business judgment alongside code knowledge. Candidates with field experience but limited exam prep consistently underperform on the Planning and Safety sections, which together make up nearly 40% of the exam.

Exam overview

The C-36 exam is administered by PSI Services at testing centers throughout California. It is closed book — no code books, notes, or reference materials are permitted in the testing room. A non-programmable calculator is permitted. The exam is computer-administered and draws from the 2022 California Plumbing Code, Cal/OSHA Title 8 regulations, and CSLB business and trade law. Before sitting the exam, you must meet CSLB experience requirements: four years of journeyman-level experience in the plumbing trade within the last ten years, with at least one year as a foreman or supervising employee. The exam fee is $60 per attempt. PSI reports your result immediately at the end of your session. There is no waiting period between retakes.

Hardest topics on the exam

Three areas cause the most failures on the C-36. First, the Safety section: at 17% of the exam, Cal/OSHA Title 8 is a significant weight that many experienced plumbers underestimate. The exam tests specific regulatory requirements — trench protective system requirements at different soil types and depths, confined space classification, and PPE requirements for specific hazards — not general safety awareness. Candidates who have been working safely for years without studying the specific Title 8 regulations consistently miss 8 to 10 questions in this section. Second, pipe sizing calculations in the Planning section: the exam presents commercial or residential scenarios and asks candidates to size pipe based on fixture unit counts and developed length. These require knowing the sizing tables and the calculation method — not just recognizing when to use them. Third, permit and code compliance judgment: the Service and Remodel section tests when a permit is required for repair work, what triggers a full upgrade to current code, and how to handle existing non-compliant conditions discovered during service calls. These are scenario-based questions with no single code section to look up — they require applied judgment built through practice.

Frequently asked questions

• How many questions are on the California C-36 plumbing contractor exam?

  115 multiple-choice questions, all scored. You have 3 hours and 30 minutes — roughly 109 seconds per question. The exam is closed book with no reference materials permitted.

• What score do you need to pass?

  72% — at least 83 correct answers out of 115. PSI reports your result immediately when you finish the exam session.

• Is the C-36 exam open book?

  No. The C-36 is closed book — no code books, notes, or reference materials are permitted in the testing room. A non-programmable calculator is permitted. This makes memorization of key code requirements, pipe sizing tables, and Cal/OSHA regulations essential.

• What topics are on the C-36 exam?

  Five topics weighted by the CSLB content outline: Planning and Estimating (22%), Underground and Rough Systems (22%), Finish Plumbing Installations (20%), Service, Repair and Remodel (19%), and Safety — Cal/OSHA Title 8 (17%).

• What experience do I need before I can sit the exam?

  CSLB requires four years of journeyman-level experience in the plumbing trade within the last ten years. At least one year of that experience must be as a foreman, supervising employee, or contractor. You must also pass a CSLB Law and Business exam in addition to the C-36 trade exam.

• Who administers the C-36 exam?

  PSI Services, contracted by the CSLB. You register through CSLB's licensing process, which issues an authorization to test (ATT) letter. You then schedule your exam session directly with PSI.

• Is there a waiting period to retake if I fail?

  No mandatory waiting period. You can reschedule with PSI as soon as a test slot is available, though CSLB limits the total number of attempts before requiring additional review.

• Does the C-36 exam cover business and law topics?

  The C-36 trade exam focuses on plumbing installation, code, and safety. However, CSLB also requires a separate Law and Business exam covering contractor licensing law, workers' compensation, contracts, and business practices. Both exams must be passed to obtain the C-36 license.

• Which code edition does the C-36 use?

  The 2022 California Plumbing Code (CPC) is the primary code reference, along with Cal/OSHA Title 8 regulations for the Safety section. The CSLB updates exam content to current code editions on a rolling basis — confirm the active edition with CSLB before your exam date.

• What is the difference between the C-36 and the I3 plumbing inspector exam?

  The C-36 licenses you to perform plumbing work as a contractor. The I3 certifies you to inspect plumbing installations for code compliance as a building inspector. The C-36 is closed book and tests practical installation, estimating, and safety knowledge. The I3 is open book and tests code enforcement and inspection procedures. Both cover the 2022 CPC but from different perspectives.