TX-ME Exam Domains 2026: Complete Guide to All 20 Content Areas

How the TX-ME Exam Is Structured

The Texas Master Electrician License Exam, administered through PSI on behalf of the Texas Department of Licensing and Regulation (TDLR), is not one test with a single score. It's two separately timed and separately passed portions that together draw from 20 content domains. Understanding how those domains are grouped - and how heavily each one is weighted - is the single most useful thing you can do before you open a study guide.

The NEC Knowledge portion covers Domains 1 through 10 and presents 75 administered questions (70 scored, 5 unscored) in 150 minutes. The Calculations portion covers Domains 11 through 20 and presents 33 administered questions (30 scored, 3 unscored) in 170 minutes. That's 108 total administered questions and 320 minutes of combined testing time - but the two clocks don't share time. If you finish Knowledge early, that leftover time cannot roll into Calculations.

Notice that several domain names repeat between the two portions - "Electrical Services," "Electrical Feeders," "Motors and Generators," and others appear in both the Knowledge list and the Calculations list. These are not duplicates. Domain 2 (Knowledge) tests your conceptual understanding of services; Domain 12 (Calculations) tests your ability to size and calculate them. Treat repeated names as two different skill sets, not one topic you can study once.

NEC Knowledge Portion: Domains 1-10

The Knowledge portion is built from ten domains, each with an official scored-item allocation out of 70 total scored questions. Two domains - Services and Branch Circuit Conductors - are jointly the largest, each accounting for 11 of the 70 scored questions.

Calculations Portion: Domains 11-20

The Calculations portion mirrors the Knowledge domain names but shifts the focus to math: load calculations, conductor sizing math, and demand factor application. Ten domains share 30 scored questions, and the distribution is far less even than on the Knowledge side.

Domain Weight Comparison Table

Laying the two portions side by side makes the priorities obvious: Services matters most everywhere, motors carry real weight in Calculations, and several domains barely register on the Calculations side despite being substantial on the Knowledge side.

For a deeper breakdown of how these weights translate into a required passing score, see the TX-ME Passing Score 2026: Exactly What You Need to Pass guide.

Registration, Fees, and Testing Mechanics

Before any domain content matters, you need to be eligible and registered. TDLR requires 12,000 supervised on-the-job hours under a Texas-licensed Master Electrician plus a Journeyman Electrician license held for at least two years - a Journeyman Industrial license does not satisfy this requirement. Supervising masters must verify your experience, and TDLR approval is required before you can schedule a test. Once approved, you must complete licensing requirements within one year after TDLR receives your application.

On the cost side, the TDLR license application fee is $45, and PSI charges $78 to take both portions together, or $78 to retake one or both portions if you need to reschedule after a failed attempt. Testing is computer-based, multiple-choice, and open-book, offered in English and Spanish at PSI test centers.

For a complete fee breakdown across the license, renewal, and exam attempts, see TX-ME Certification Cost 2026: Complete Pricing Breakdown. If you're trying to plan around PSI's testing calendar and TDLR's one-year completion window, check TX-ME Exam Dates 2026: Testing Windows, Deadlines & Scheduling.

Open-Book Rules and Allowed References

The exam is open-book, but "open-book" has strict limits. You must bring an approved softbound NEC - NEC Handbooks, loose-leaf, spiral, and ring-bound copies are prohibited, as are added papers inserted into the book. Notes, highlighting, and underlining prepared before test day are allowed, but tabs must be permanent, NEC-publisher-manufactured or supplied tabs, and you cannot write in your reference during testing itself.

You're also permitted a silent, battery-operated, nonprinting, nonprogrammable calculator without alphabetic capability - critical for the Calculations portion's load and sizing math across Domains 11 through 20.

Because the PSI bulletin revised July 9, 2026 requires the 2026 NEC for examinations from September 1, 2026, confirm which code edition your test date requires before tabbing your book - a 2023-edition codebook tabbed for the wrong domains wastes preparation time.

Mapping a Study Schedule to the 20 Domains

Generic study techniques only help if they're pointed at the right domains. Given that Domains 2, 4, and 12 alone account for a disproportionate share of scored questions across both portions, a reasonable framework is to front-load your calendar with the heaviest domains, then use spaced review sessions to keep lighter domains from being forgotten entirely.

For a fuller walkthrough of pacing, retake strategy, and how to structure practice sessions around the two separately timed portions, read the TX-ME Study Guide 2026: How to Pass on Your First Attempt. If you're still gauging overall difficulty before committing to a schedule, How Hard Is the TX-ME Exam? Complete Difficulty Guide 2026 and TX-ME Pass Rate 2026: What the Data Shows both provide useful context grounded in TDLR's own reported figures.

Running full-length, domain-tagged practice sets on our TX-ME practice test platform is one of the most direct ways to see which of the 20 domains still need work before you commit to a test date.

Who Hires for This License

A Texas Master Electrician license is the credential that lets an individual supervise electrical work, sign off on installations, and - if paired with a separate Electrical Contractor business license - operate or manage a contracting business. Electrical contracting firms, industrial facilities, and property management operations across Texas look for master-licensed electricians to supervise journeyman and apprentice crews, review plans, and take responsibility for code-compliant installations across the same systems tested in Domains 1-20: services, feeders, branch circuits, motors, special occupancies, and renewable energy systems.

Because the individual Master Electrician license is distinct from the Electrical Contractor business license, passing this exam qualifies you to hold the individual credential - running a contracting business is a separate licensing track. For a broader look at where the license leads professionally, see TX-ME Jobs and Is the TX-ME Certification Worth It? Complete ROI Analysis 2026.

Once licensed, maintaining the credential requires attention too: the individual license is valid for one year, renews for $45, and requires four TDLR-approved continuing education hours per cycle covering the NEC, Texas law and rules, and NFPA 70E electrical safety - a cycle that effectively keeps you revisiting several of the same 20 domains year after year.

Frequently Asked Questions