- AZ-PLB refers to the Arizona C-37/CR-37 Plumbing Contractor trade exam administered through PSI.
- The trade exam has 100 scored questions, a 240-minute limit, and a 70% passing score.
- It's open book, but only with approved references like the 2018 IPC, IMC, IFGC, and specific NFPA standards.
- Drainage Waste and Vents is the largest of the 13 domains and deserves extra study time.
What Is AZ-PLB, Exactly?
AZ-PLB is the site identifier used on this site for the Arizona Plumbing Contractor (C-37/CR-37) Trade Exam, the trade competency test required by the Arizona Registrar of Contractors (ROC) for anyone seeking a plumbing contractor license in the state. It is not a generic industry credential - it's a state-specific licensing exam tied directly to Arizona statute and ROC classification rules.
There are two closely related license classifications built around this exam. The C-37 classification covers commercial plumbing work, while CR-37 covers dual commercial and residential plumbing work. A separate residential-only exam, the R-37R, exists outside the scope of this trade exam and should not be confused with it. If you're unsure which classification applies to your business plans, the ROC's classification list is the authoritative reference.
Because "AZ-PLB" is used loosely elsewhere online for unrelated credentials, it's worth being precise here: everything on this site refers specifically to the Arizona C-37/CR-37 trade exam, its PSI-administered content outline, and the licensing process that surrounds it.
Who Administers the Exam
The Arizona Registrar of Contractors sets the licensing requirements, while PSI is the testing organization that develops and delivers the C-37 (CR-37) Plumbing trade examination itself. Candidates also need to complete a separate Statutes and Rules Exam (SRE), which is an online course and exam delivered through GMetrix rather than PSI. The trade exam and the SRE are two distinct requirements with separate costs and separate delivery systems - don't assume passing one satisfies the other.
For a broader breakdown of exactly what each exam covers and how the two relate to the licensing process, the AZ-PLB Requirements 2026: Eligibility, Prerequisites & How to Qualify guide walks through the full sequence.
Exam Format and Scoring
The trade exam outline is built around 100 scored questions, with a time allowance of 240 minutes. PSI may also insert 5 to 10 unscored experimental questions within that same time block - these are indistinguishable from scored items during the test, which is one reason time management across the full 240 minutes matters even if the scored count is fixed at 100.
To pass, candidates need to score 70%. The exam is delivered as computer-based multiple choice, and you can take it either at a physical PSI test center or through remote proctoring, depending on what's available and what you're comfortable with.
Key Takeaway
Budget your 240 minutes as if all 100-110 questions count, since you can't identify which items are unscored experimental questions during the test.
One important logistical difference: test centers allow a basic silent, nonprinting, nonprogrammable, nonscientific calculator, but remote proctored sessions prohibit scratch paper and do not allow breaks. If you know you'll need to work multi-step pipe-sizing or drainage calculations, that distinction alone may steer you toward an in-person test center rather than remote testing. For a deeper look at how tough the format actually feels in practice, see How Hard Is the AZ-PLB Exam? Complete Difficulty Guide 2026.
The 13 Content Domains
The trade exam outline (last revised January 20, 2022) is organized into 13 domains. Each represents a distinct area of plumbing code knowledge and field practice that the exam draws questions from. Understanding relative weight matters: Drainage Waste and Vents is the largest domain, meaning it deserves proportionally more of your prep time than any single other topic.
Domain 1: Drainage Waste and Vents (Largest Domain)
This is the anchor domain of the exam. Expect questions on pipe sizing, slope requirements, vent placement, trap arm limits, and how drainage and venting systems interact under the 2018 IPC.
- Fixture unit calculations for drain and vent sizing
- Vent types (common, wet, circuit, individual) and when each applies
- Cleanout placement and access requirements
Domains 2-5: Indirect Waste, Water Supply, Backflow Prevention, Roof Drains/Storm Drainage
These domains cover how water moves into and out of a building safely. Backflow prevention questions often test device selection based on hazard level, while water supply questions lean on pipe sizing and pressure loss concepts.
- Indirect waste receptor sizing and air-gap requirements
- Water distribution pipe sizing methods
- Backflow preventer types matched to cross-connection risk
- Roof drain and secondary (overflow) drainage sizing
Domains 6-9: Fixtures, General Knowledge, Specialty/Interceptors/Traps, Fuel Gas
This block spans fixture installation (including water heaters and accessibility clearances), broad code-application knowledge, grease and oil interceptors, and fuel gas piping under the 2018 IFGC.
- Water heater venting, relief valves, and seismic strapping
- ADA-influenced accessibility clearances for fixtures
- Interceptor and trap sizing for specialty waste
- Fuel gas pipe sizing and appliance venting categories
Domains 10-13: Septic/Sewer, Hydronics, Fire Sprinklers, Excavation
The final domains cover onsite wastewater systems (governed by Arizona-specific rules), hydronic heating piping, fire sprinkler basics tied to NFPA 13/13D/13R, and excavation safety referencing OSHA 1926.
- Septic and sewer connection requirements under Arizona onsite-wastewater rules
- Hydronic piping and system component identification
- NFPA 13, 13D, and 13R distinctions for sprinkler systems
- Trench safety and excavation protection per OSHA 1926
For a full breakdown of every domain with study emphasis and cross-references to the code books, see AZ-PLB Exam Domains 2026: Complete Guide to All 13 Content Areas.
Open-Book References You're Allowed to Use
Unlike many licensing exams, the AZ-PLB trade exam is open book - but only with the specific approved references, not any code book you own. The approved list includes:
- 2018 International Plumbing Code (IPC)
- 2018 International Mechanical Code (IMC)
- 2018 International Fuel Gas Code (IFGC)
- NFPA 13 (2016)
- NFPA 13D (2007)
- NFPA 13R (2007)
- OSHA 1926
- Listed Arizona onsite-wastewater rules
You're allowed to bring pre-existing notes, highlighting, and permanent tabs already in your references. What's prohibited: extra loose papers and writing directly in the references during the exam. This means your prep work - tabbing key tables, highlighting sizing charts - has to happen before test day, not during it.
Registration, Fees, and Retakes
The trade exam costs $66 per attempt, paid to PSI. This is separate from the Statutes and Rules Exam, which runs $61 and is delivered as an online GMetrix course and exam rather than an in-person or remote-proctored test. Candidates should plan for both costs as part of the total path to licensure. A full pricing breakdown, including how these two exams stack against license and bond costs, is covered in AZ-PLB Certification Cost 2026: Complete Pricing Breakdown.
If you don't pass on your first try, you'll need to wait 30 days before retaking the trade exam. That wait extends to 90 days once you've failed three attempts. This escalating retake structure is a strong argument for treating your first attempt seriously rather than planning to "test and see."
| Item | Detail |
|---|---|
| Trade exam fee | $66 per attempt (PSI) |
| Statutes and Rules Exam fee | $61 (GMetrix, online) |
| Scored questions | 100 |
| Unscored experimental questions | 5-10 (blended in) |
| Time allowed | 240 minutes |
| Passing score | 70% |
| Retake wait (attempts 1-3) | 30 days |
| Retake wait (after 3rd fail) | 90 days |
For exact scheduling windows and how to book a seat at a test center or remotely, check AZ-PLB Exam Dates 2026: Testing Windows, Deadlines & Scheduling. And if you want the numeric breakdown of exactly what 70% means in terms of missed questions, AZ-PLB Passing Score 2026: Exactly What You Need to Pass covers it in detail.
Who Needs to Take AZ-PLB
The trade exam is required for the individual acting as the qualifying party on a C-37 or CR-37 contractor license application. To sit for it, that person generally needs four years of practical or management trade experience, with at least two of those years falling within the preceding ten years. Qualifying technical education can offset up to two years of that experience requirement.
In practice, this means the exam is aimed at experienced plumbers stepping into a contractor or qualifying-party role - not entry-level apprentices. Companies hiring for licensed plumbing contractor positions, foremen who plan to run their own crews, or plumbers looking to formally qualify a business all end up needing this exam. If you're researching whether pursuing this license fits your career plans, AZ-PLB Jobs and Is the AZ-PLB Certification Worth It? Complete ROI Analysis 2026 both dig into how the license gets used in the field.
After You Pass: Licensing Steps
Passing the trade exam isn't the finish line - it's a gate you pass through on the way to an actual ROC license. Once you pass, you have two years to apply for the license before the passing score expires. After that, licenses must be renewed every two years, along with applicable fees, a contractor bond, and business-compliance requirements set by the ROC.
This two-year application window is easy to overlook if you pass the exam early and then get busy with other licensing steps like bonding or business registration. Mark the date you passed and build your application timeline around it.
Key Takeaway
You have two years after passing to apply for your license - don't let bonding or paperwork delays push you past that window.
Preparing for the Content, Not Just the Test
Because Drainage Waste and Vents carries the most weight, it makes sense to schedule it earliest and revisit it most often, rather than treating every domain equally in a generic study rotation. A simple way to structure a multi-week plan: front-load the largest domain, then work through the mid-weight domains (water supply, backflow, fixtures, fuel gas) before finishing with the smaller, more specialized domains like hydronics, fire sprinklers, and excavation.
Drainage Waste and Vents Deep Dive
- Work through IPC drainage and venting chapters
- Practice fixture-unit and pipe-sizing problems by hand
- Tab your code book's sizing tables ahead of test day
Water Systems and Fixtures
- Cover Water Supply, Backflow Prevention, and Indirect Waste domains
- Review fixture installation, water heater code, and accessibility clearances
Fuel Gas, Septic/Sewer, Roof Drainage
- Study IFGC pipe sizing and venting categories
- Review Arizona onsite-wastewater rules for septic/sewer questions
Specialty Topics and Full Review
- Cover Hydronics, Fire Sprinklers, and Excavation domains
- Run full-length timed practice sessions using your tabbed references
For a structured, week-by-week plan built entirely around AZ-PLB's domain weighting, see the AZ-PLB Study Guide 2026: How to Pass on Your First Attempt. And if you want a condensed reference for last-minute review, the AZ-PLB Cheat Sheet 2026: One-Page Review of Must-Know Facts is built for exactly that. Running full-length timed practice questions on our practice test platform before test day is one of the most direct ways to get comfortable with the 240-minute pacing and open-book reference workflow.
FAQ
No. AZ-PLB refers to the C-37 (commercial) and CR-37 (dual commercial/residential) trade exam. The R-37R residential-only exam is a separate test with its own outline.
You can bring the specific approved references, including the 2018 IPC, IMC, IFGC, NFPA 13/13D/13R, OSHA 1926, and listed Arizona onsite-wastewater rules, with pre-existing notes, highlighting, and permanent tabs already in place. Extra loose papers and writing in the references during the exam are not allowed.
There are 100 scored questions, plus PSI may add 5 to 10 unscored experimental questions within the same 240-minute time limit. You won't know which questions are experimental during the test.
You must wait 30 days before retaking the exam. If you fail three attempts, that wait increases to 90 days before your next attempt.
No, they're separate. The trade exam ($66, PSI) tests plumbing code and field knowledge. The Statutes and Rules Exam ($61) is a separate online course and exam delivered through GMetrix.