What Is A OK-MECH?

What Is a OK-MECH, Exactly?

"OK-MECH" is the identifier used on this site for the Oklahoma Mechanical Trade License Exam covering the HVACR Contractor Unlimited classification. It is not a national certification badge you print on a business card - it is the state-administered trade competency examination that a person must pass, alongside a separate Business and Law exam, before the Oklahoma Construction Industries Board (CIB) will issue an Unlimited mechanical contractor license authorizing HVAC/R work without tonnage or Btu/h restrictions.

If you've searched other sites and found conflicting numbers about fees, question counts, or domain weights, that's because the "OK-MECH" acronym is sometimes reused for unrelated credentials. Everything on this page describes the Oklahoma HVACR Contractor Unlimited trade exam specifically, sourced from the current PSI candidate bulletin and CIB rules. For a broader look at how this fits into the full mechanical licensing structure, see OK-MECH Certification and What Is OK-MECH?.

Who Governs and Administers the Exam

Two organizations sit behind every OK-MECH question and every licensing decision:

• Oklahoma Construction Industries Board (CIB): The state agency that sets licensing rules, reviews applications, verifies experience, and issues the contractor license once both exam portions are passed.
• PSI Services LLC: The third-party testing vendor that writes and delivers the computer-based exam, publishes the candidate bulletin, and enforces testing-center policies on references, tabs, and calculators.

The current PSI bulletin governing this exam is effective August 31, 2026, and it's the authoritative source for question counts, allowed references, and timing. If you want the full picture of eligibility rules before you register, read OK-MECH Requirements 2026: Eligibility, Prerequisites & How to Qualify.

Trade Exam Format: Questions, Time, Passing Score

The HVACR Contractor Unlimited trade exam consists of 90 computer-based questions delivered over 240 minutes, with a required score of 70% to pass. PSI may embed up to 10 additional unscored, experimental questions used to evaluate future exam content - these look identical to scored items, and importantly, the time spent answering them does not count against your 240-minute allotment.

The practical implication: you can't identify which questions are experimental, so every item deserves your full attention. Pacing yourself at roughly 2.5 minutes per question (accounting for the possibility of extra unscored items) keeps you comfortable rather than rushed.

For a deeper dive into exactly how the 70% threshold is calculated and what score you need to clear on test day, see OK-MECH Passing Score 2026: Exactly What You Need to Pass. If you're wondering how tough this exam actually feels compared to other trade exams, How Hard Is the OK-MECH Exam? Complete Difficulty Guide 2026 breaks that down in detail.

The Six Content Domains

The trade exam's 90 questions are divided into six official subject areas. Together they add up to the full exam, and the allocation tells you exactly where to concentrate your review time.

For a domain-by-domain study plan with recommended resources for each of these six areas, see OK-MECH Exam Domains 2026: Complete Guide to All 6 Content Areas.

The Separate Business and Law Exam

OK-MECH candidates must also pass a distinct Business and Law examination before licensure. This portion has 50 questions in 120 minutes and also requires a 70% passing score. It is scheduled and paid for separately from the trade exam, and both portions must be completed within three years of your eligibility approval under CIB rules.

Because the Business and Law content is unrelated to HVAC/R technical knowledge - covering contracting regulations, licensing law, and business practices - many candidates study for it independently rather than folding it into their trade-exam prep schedule.

Who Can Sit for the Unlimited Trade Exam

Eligibility for the HVACR Contractor Unlimited exam is more specific than simply "having HVAC experience." Applicants must:

• Be at least 18 years old.
• Meet the mechanical journeyman experience requirements, plus one additional year of qualifying experience beyond journeyman level.
• Be an owner, partner, officer, or permanent employee of a mechanical firm.
• Document qualifying work specifically on equipment above 25 tons and 500,000 Btu/h - this is what distinguishes the Unlimited classification from a limited-tonnage contractor license.

The standard experience-only path totals four years, though approved education can reduce the journeyman-level experience component. Experience certifications and, where applicable, school transcripts are submitted to the CIB as part of the application package. Full eligibility mechanics, including how education credit is calculated, are covered in OK-MECH Requirements 2026: Eligibility, Prerequisites & How to Qualify.

Fees and Costs at Each Stage

Budgeting for OK-MECH involves several distinct payments, not a single exam fee:

Active contractor licensing also requires maintaining a $5,000 surety bond and $50,000 commercial general liability insurance - ongoing costs that exist outside the CIB fee schedule but are mandatory for holding the license. For the complete cost picture, including how retake fees stack up if you need multiple attempts, see OK-MECH Certification Cost 2026: Complete Pricing Breakdown.

Open-Book References Allowed at the Testing Center

Unlike closed-book exams, OK-MECH permits candidates to bring specific approved references into the PSI testing center. The current allowed list includes:

• The specified mechanical and fuel-gas codes
• An approved refrigeration textbook
• An OSHA reference
• ACCA Manual N
• Mathematics for Plumbers and Pipefitters
• An ACCA ductulator

Pre-highlighting and permanent tabs in your reference books are allowed, but handwritten notes are prohibited - PSI proctors check for this during check-in. A PSI-compliant non-programmable calculator is also permitted.

Code and textbook editions matter and change on fixed dates. The 2024 IMC and IFGC become usable on September 14, 2026, while the 2018 editions stop being allowed on December 14, 2026 - creating a transition window where either edition may be acceptable. Similarly, Modern Refrigeration and Air Conditioning, 22nd edition, became usable August 13, 2026, and both its 20th edition and Refrigeration and Air Conditioning Technology, 5th edition, cease to be allowed on November 1, 2026. Check the current PSI bulletin before your test date to make sure your physical copies are the correct editions - bringing an outdated edition after its cutoff date can mean it's turned away at check-in.

Scheduling Your Study Around the Six Domains

Because Air Distribution Systems and Refrigeration and Air Conditioning Systems together account for 45 of the 90 questions, your study calendar should weight those two domains heaviest, while still touching every domain at least once before test day.

This is a light structural framework, not a rigid formula - some candidates need more weeks depending on how much field experience they already have in each domain. For a complete first-attempt study system built specifically around this exam's format and references, see OK-MECH Study Guide 2026: How to Pass on Your First Attempt. You can also run realistic timed practice sessions through our practice test platform to build familiarity with the 240-minute pacing before test day.

Retakes, Renewal, and Continuing Education

If you don't pass on your first attempt, Oklahoma's retake rules impose waiting periods: 30 days after a first failure and 90 days after each subsequent failure. Both the trade exam and the Business and Law exam must be passed within three years of eligibility approval, so repeated failures on either portion can put your approval window at risk.

Once licensed, contractors renew annually in their birth month for a $200 renewal fee. Continuing education requires six approved hours every 36 months, though there's an initial three-year exemption from this requirement right after first obtaining the license.

Understanding how retake timing interacts with the three-year eligibility clock is one of the more overlooked planning details - for a data-informed look at how candidates typically perform and where retakes tend to happen, see OK-MECH Pass Rate 2026: What the Data Shows.

Who Actually Hires for This License

The Unlimited mechanical contractor license built around OK-MECH is typically sought by HVAC/R professionals who want to operate or lead work on larger commercial systems - beyond the 25-ton, 500,000 Btu/h residential-scale threshold. That includes mechanical contracting firm owners, project leads on commercial HVAC installations, and experienced journeymen moving into ownership or supervisory roles. If you're evaluating whether pursuing this license fits your career goals and what it can mean for pay and job opportunities, Is the OK-MECH Certification Worth It? Complete ROI Analysis 2026 and OK-MECH Salary Guide 2026: Complete Earnings Analysis go into more depth, and OK-MECH Jobs looks at the kinds of positions this license opens up.

Whatever stage you're at, running full-length practice sessions on our OK-MECH practice test site before you schedule with PSI is one of the simplest ways to confirm you're ready for the real 240-minute format.

Frequently Asked Questions