- NV-C21 is the Nevada C-21 Refrigeration and Air Conditioning Contractor Trade Exam, administered via PSI Services LLC for the Nevada State Contractors Board.
- The trade exam has 85 scored questions in 180 minutes, and you need 60 correct to pass.
- Trade-only registration costs $95; adding the Construction Management Survey business-and-law package brings it to $140.
- Fuel Systems carries the most weight at 10 items, followed by Refrigerants and Refrigeration at 7.
What Is NV-C21, Exactly?
NV-C21 refers specifically to the Nevada C-21 Refrigeration and Air Conditioning Contractor Trade Exam - the licensing exam Nevada requires for contractors seeking the C-21 classification. This is not a generic HVAC certificate you print off after an online course. It is a state-regulated trade competency exam tied directly to Nevada contractor licensing, and passing it is one of the gates you must clear before the Nevada State Contractors Board will consider issuing you a C-21 license.
If you've landed here searching for background on what this exam covers, how it's scored, or what it costs, you're in the right place. For a broader introduction to the credential itself, see our companion piece on NV-C21 Certification, and if you want the short version of what the acronym means, check NV-C21 Meaning or What Does NV-C21 Stand For?.
Who Administers the Exam
Two organizations sit behind the NV-C21 process. The Nevada State Contractors Board is the licensing authority - it approves your application, verifies your experience, and ultimately issues (or denies) the C-21 license. PSI Services LLC is the third-party testing vendor that builds, delivers, and scores the actual computer-based exam.
Practically speaking, this means your path runs through two systems: you apply to the Board and get an eligibility notice, then you schedule and sit for the exam through PSI. The PSI candidate bulletin governing this exam was last updated March 25, 2026, so always confirm current rules against the official bulletin before test day rather than relying solely on secondhand summaries.
Exam Format and Question Style
The C-21 trade exam is computer-based and multiple-choice. Here's what the format looks like on paper:
- 85 scored questions
- 180 minutes total testing time
- 60 correct answers minimum to pass
- PSI may insert 1 to 10 unscored experimental questions that look identical to real questions but don't count toward your score - and importantly, these still consume your clock time
That experimental-question detail matters more than most candidates realize. Because you can't tell which questions are experimental, you have to treat every question with equal seriousness, and you have to budget your 180 minutes assuming a handful of items won't contribute to your pass/fail outcome. For a deeper breakdown of how this affects pacing, see NV-C21 Passing Score 2026: Exactly What You Need to Pass.
Key Takeaway
With 85 questions and 180 minutes, you have roughly two minutes per question on average - but since experimental items eat into that time without adding to your score, moving efficiently through familiar territory (like basic piping or insulation questions) preserves time for calculation-heavy domains like Load Calculations and Fuel Systems.
The 22 Content Domains
The NV-C21 trade exam is built from 22 distinct content domains, each carrying a specific number of items out of the 85 total. Understanding this weighting is the single most useful thing you can do before you open a study guide, because it tells you exactly where to spend your limited prep hours.
| Domain | Item Count |
|---|---|
| 1. Piping | 6 |
| 2. Insulation | 1 |
| 3. Hangers and Supports | 3 |
| 4. Sound, Vibration and Seismic Control | 1 |
| 5. Heating and Cooling Principles | 3 |
| 6. Refrigerants and Refrigeration | 7 |
| 7. Load Calculations | 6 |
| 8. Testing, Adjusting and Balancing | 3 |
| 9. Controls | 5 |
| 10. Machine Room | 1 |
| 11. A/C and Heat Pump Equipment | 4 |
| 12. Furnaces and Heaters | 4 |
| 13. Hydronics | 2 |
| 14. Chimneys, Flues and Vents | 5 |
| 15. Combustion Air | 2 |
| 16. Fuel Systems | 10 |
| 17. Ducts | 6 |
| 18. Evaporative Cooling | 2 |
| 19. Chillers | 3 |
| 20. Solar | 4 |
| 21. Ventilation and Exhausts | 3 |
| 22. Safety | 4 |
Notice that Fuel Systems (Domain 16) is the single largest domain at 10 items - nearly 12% of the entire exam - followed by Refrigerants and Refrigeration (Domain 6) at 7 items. Piping, Load Calculations, and Ducts each carry 6 items. On the other end, Insulation, Sound/Vibration/Seismic Control, and Machine Room each contribute just 1 item apiece.
Fuel Systems
As the highest-weighted domain, Fuel Systems deserves disproportionate study time. Candidates should be comfortable with gas piping sizing, appliance connections, and code-driven installation requirements referenced in NFPA 54.
- Highest single-domain weight on the exam at 10 items
- Closely tied to the NFPA 54 National Fuel Gas Code reference allowed in the testing room
- Frequently intersects with Chimneys, Flues and Vents and Combustion Air questions
Refrigerants and Refrigeration
The second-heaviest domain at 7 items. Expect questions on refrigerant handling, cycle principles, and equipment behavior under varying load conditions.
- Pairs conceptually with Heating and Cooling Principles and Chillers
- Worth prioritizing early in a study plan given its weight
For a full domain-by-domain breakdown with study strategy for each of the 22 areas, see our dedicated guide: NV-C21 Exam Domains 2026: Complete Guide to All 22 Content Areas.
Fees and Registration Mechanics
Money and paperwork trip up more candidates than the technical content does. Here's exactly how the fee structure breaks down:
- $95 - trade portion of the exam alone
- $140 - trade exam plus the Construction Management Survey (business-and-law) package combined
- $300 - license application fee (separate from exam fees)
- $600 - biennial license fee once licensed
The Construction Management Survey is normally required for licensure unless it's waived, and it has its own separate passing standard distinct from the trade exam's 60-correct threshold. Don't assume passing the trade portion alone satisfies every licensing requirement - check with the Board on whether your situation qualifies for a waiver.
Licenses renew on a biennial cycle, and renewal requires paying the renewal fee and maintaining continued licensing compliance. For a complete, itemized cost picture including how these figures stack up across the whole licensing journey, read NV-C21 Certification Cost 2026: Complete Pricing Breakdown.
Eligibility and Experience Requirements
Before you're even eligible to sit for the NV-C21 trade exam, the Board needs to confirm you meet experience thresholds. Ordinarily, candidates need four years of qualifying experience as a journeyman, foreman, supervising employee, or contractor within the preceding fifteen years. Approved education can substitute for up to three of those four years, but it cannot eliminate the experience requirement entirely.
Beyond raw experience, expect the Board to conduct experience verification along with a financial and background review. A license bond and applicable insurance requirements accompany the licensing process as well - these aren't optional extras, they're part of what stands between eligibility notice and an active license.
Only after the Board approves your application and issues an eligibility notice can you schedule your computer-based test through PSI. For the complete rundown of qualifying experience categories, education substitutions, and documentation expectations, see NV-C21 Requirements 2026: Eligibility, Prerequisites & How to Qualify.
Open-Book References Allowed
Unlike many licensing exams, the NV-C21 trade exam is open book - but the list of what you can bring is short and strictly enforced:
- 2018 Uniform Mechanical Code
- NFPA 54 National Fuel Gas Code, 2012 edition
That's it. No other code books, manuals, or reference material are permitted. Within those two allowed books, you're permitted to bring copies with pre-highlighting, underlining, and permanent tabs already in place. What's not allowed: handwritten notes, temporary tabs (like sticky flags you can move around), or any loose inserted material such as printed cheat sheets or index cards tucked between pages.
A silent, non-programmable calculator that meets PSI's restrictions is also allowed - useful given how many Load Calculations and Fuel Systems questions involve numeric work.
Key Takeaway
Because only pre-marked tabs and highlighting are permitted, your prep work should happen on your actual reference copies well before test day - tab your 2018 UMC and 2012 NFPA 54 by domain (Fuel Systems, Chimneys/Flues/Vents, Combustion Air) so you can navigate quickly under time pressure.
Who Takes the NV-C21 and Why
The NV-C21 trade exam is aimed at people pursuing a C-21 Refrigeration and Air Conteering Contractor license in Nevada - typically journeyman-level HVAC/R technicians, foremen, and supervising employees who've accumulated the required field experience and are ready to operate as licensed contractors rather than employees. Passing this exam (plus, in most cases, the Construction Management Survey) is a prerequisite step toward that license, not an end in itself.
If you're weighing whether pursuing this path is worth the time and fees involved, our analysis piece walks through the tradeoffs: Is the NV-C21 Certification Worth It? Complete ROI Analysis 2026. And if you're curious about how licensed C-21 contractors typically find work once licensed, see NV-C21 Jobs.
How to Approach Preparation
Generic study advice only goes so far here - the smarter approach is to let the domain weighting drive your schedule. Since Fuel Systems (10 items) and Refrigerants and Refrigeration (7 items) together account for roughly a fifth of the exam, they deserve early, repeated attention rather than being treated as "just another chapter."
High-Weight Domains
- Fuel Systems (10 items) - gas piping, appliance hookups, NFPA 54 references
- Refrigerants and Refrigeration (7 items) - cycle principles, handling procedures
Mid-Weight Domains
- Piping, Load Calculations, and Ducts (6 items each)
- Controls and Chimneys/Flues/Vents (5 items each)
Remaining Domains and Full Practice
- A/C and Heat Pump Equipment, Furnaces and Heaters, Solar, Safety (4 items each)
- Timed practice sets simulating the 85-question, 180-minute format
- Review reference-book tabbing on the 2018 UMC and 2012 NFPA 54
Practicing under realistic timed conditions matters especially given the experimental-question wrinkle - you won't know which questions count, so building stamina across the full 180 minutes is important. Our step-by-step walkthrough goes deeper into structuring a complete plan: NV-C21 Study Guide 2026: How to Pass on Your First Attempt. If you're still calibrating how difficult this exam actually is relative to your current experience level, read How Hard Is the NV-C21 Exam? Complete Difficulty Guide 2026, and for outcome data see NV-C21 Pass Rate 2026: What the Data Shows.
Once you're ready to test your recall against realistic scored practice questions modeled on the real domain weighting, our practice test platform lets you drill each of the 22 domains individually before attempting a full timed simulation. Many candidates also use the main practice site to track weak domains over multiple sessions rather than guessing where they stand.
Frequently Asked Questions
No. NV-C21 refers to the Nevada C-21 Refrigeration and Air Conditioning Contractor Trade Exam, administered by the Nevada State Contractors Board through PSI Services LLC. It applies specifically to Nevada contractor licensing.
The trade exam has 85 scored questions delivered over 180 minutes, and you need at least 60 correct answers to pass. PSI may also include up to 10 unscored experimental questions that count against your time but not your score.
The exam is open book, but only the 2018 Uniform Mechanical Code and the 2012 NFPA 54 National Fuel Gas Code are allowed. You may bring copies with pre-highlighting, underlining, and permanent tabs, plus a silent non-programmable calculator meeting PSI's rules. Handwritten notes, temporary tabs, and loose inserts are not permitted.
You must wait two weeks before retesting. If you fail three times, your application is voided, and you'd need to wait 30 days before reapplying from scratch.
Normally yes, unless waived. It's a separate business-and-law exam component with its own passing standard, distinct from the C-21 trade exam. Registering for both together costs $140 versus $95 for the trade exam alone.