Texas - Master Electrician - Calculations Portion

Texas Master Electrician Calculations Exam: Complete 2026 Prep Guide

The master electrician calculations exam is where a lot of candidates hit a wall. The math is real, the NEC is thick, and the pressure is on. But here's the good news: this exam is absolutely passable with the right preparation. If you're working toward your TX Master Electrician license, the Calculations Portion tests the skills you've been building throughout your career — transformer sizing, conductor ampacity, motor protection, conduit fill, and more. This guide walks you through everything you need to know about the exam format, the topics covered, and how to study smart. You can also start testing yourself right now with our free practice exam.

Texas Master Electrician Calculations Exam Overview

The Calculations Portion of the Texas Master Electrician exam consists of 33 total items, but only 30 of those are scored — 3 items are non-scored pilot questions that don't affect your result. You have 170 minutes to complete the exam, and you need to answer at least 70% of the scored questions correctly to pass.

The exam is administered by PSI and is open book — you must bring your own soft-bound copy of the NEC 2023. Loose-leaf, spiral-bound, or ring-bound copies are not allowed. The NEC Handbook is also not permitted. You may use a calculator, but it must be non-programmable, silent, battery-operated, and free of an alphabetic keyboard or paper tape printer.

One important detail: the Master Electrician exam has two portions — the NEC Knowledge Portion and the Calculations Portion. The combined exam fee is $78. If you fail one or both portions, the retake fee is also $78. Check the official exam bulletin for the latest scheduling and eligibility information.

Topics Covered on the Master Electrician Calculations Exam

The Calculations Portion spans ten subject areas. Here's what you'll see:

• Calculations and Theory — Foundational math and electrical theory underlying all other topics
• Electrical Services, Service Equipment, and Separately Derived Systems — Service entrance sizing, transformer secondaries, system grounding
• Electrical Feeders — Feeder conductor sizing, demand factors, overcurrent protection
• Branch Circuit Calculations and Conductors — Load calculations, conductor ampacity, OCPD sizing for branch circuits
• Electrical Wiring Methods and Electrical Materials — Conduit fill, raceway selection, box fill
• Electrical Equipment and Devices — Box volume calculations, device ratings, equipment requirements
• Motors and Generators — Full-load current, conductor sizing, overcurrent and overload protection
• Electrical Control Devices and Disconnecting Means — Disconnect ratings, control circuit requirements
• Special Occupancies, Equipment, and Conditions — Hazardous locations, healthcare facilities, swimming pools
• Renewable Energy Technologies — Solar PV, battery systems, inverter calculations

Motors and Generators and Electrical Services tend to be heavily tested areas, so give those topics extra attention during your study sessions.

Sample Texas Master Electrician Calculations Questions

These sample questions give you a realistic feel for what you'll face on exam day. Work through them — but we're not going to give you the answers here. Take our free practice exam to check your thinking.

Question 1 — Electrical Equipment and Devices

A device box contains the following 12 AWG conductors: 4 circuit conductors entering from one cable, 2 circuit conductors entering from another cable, and 3 equipment grounding conductors. The box also contains one duplex receptacle (connected to 12 AWG conductors) and one set of internal cable clamps. What is the MINIMUM volume required for this box?

• A) 18.00 cu in
• B) 20.25 cu in
• C) 22.50 cu in
• D) 27.00 cu in

This is a box fill calculation — you'll need to count each conductor, device, and fitting according to NEC Article 314 and apply the correct cubic-inch allowance per conductor size.

Question 2 — Electrical Wiring Methods and Electrical Materials

An electrician needs to install 12 THHN copper conductors (6 AWG) and 8 THHN copper conductors (10 AWG) in a single EMT raceway. What is the minimum trade size EMT required?

• A) 1-1/4"
• B) 1-1/2"
• C) 2"
• D) 2-1/2"

Conduit fill problems require you to look up the cross-sectional area of each conductor, total them up, and find the minimum raceway size from the NEC fill tables.

Question 3 — Electrical Services, Service Equipment, and Separately Derived Systems

A separately derived system uses a 112.5 kVA, 3-phase transformer with a 480V delta primary and 208Y/120V secondary. What is the minimum ampacity required for the secondary conductors if the load is continuous?

• A) 312A
• B) 390A
• C) 541A
• D) 676A

This one involves calculating secondary full-load current from kVA and voltage, then applying the continuous load factor. Harder questions like this one reward candidates who practice the math until it's second nature.

Question 4 — Electrical Services, Service Equipment, and Separately Derived Systems

A 208Y/120V, 3-phase, 4-wire service has a calculated demand load of 86,000 VA. What is the minimum ampacity required for the ungrounded service entrance conductors?

• A) 207A
• B) 239A
• C) 358A
• D) 414A

Service conductor sizing requires the right 3-phase power formula. Knowing whether to apply a continuous load multiplier here is part of what makes these questions tricky.

Question 5 — Electrical Control Devices and Disconnecting Means

A 75 HP, 208V, 3-phase motor is to be protected with time-delay (dual-element) fuses. Per NEC Table 430.52, what is the maximum standard fuse size permitted (disregarding exceptions)?

• A) 350A
• B) 369A
• C) 400A
• D) 500A

Motor overcurrent protection questions require you to find the full-load current from NEC Table 430.250, multiply by the correct percentage from Table 430.52, then round to the next standard fuse size.

What Types of Questions to Expect — by Topic

Our full practice exam bank contains 178 questions across all ten topic areas. Here's a breakdown of what each section covers and how many practice questions we offer:

• Calculations and Theory (12 questions) — Ohm's Law applications, power factor, apparent vs. true power, and the foundational formulas that show up throughout the rest of the exam.
• Electrical Services, Service Equipment, and Separately Derived Systems (48 questions) — This is the largest section in our bank and for good reason. Expect transformer secondary sizing, service entrance conductor ampacity, grounded conductor requirements, and system grounding calculations.
• Electrical Feeders (18 questions) — Feeder sizing based on demand load, conductor ampacity corrections, and overcurrent device selection for multi-circuit feeders.
• Branch Circuit Calculations and Conductors (24 questions) — Load calculations for lighting, receptacles, and appliances; conductor sizing with correction and adjustment factors; and OCPD selection.
• Electrical Wiring Methods and Electrical Materials (12 questions) — Conduit fill calculations for various raceway types (EMT, PVC, rigid), conductor cross-sections, and material selection requirements.
• Electrical Equipment and Devices (12 questions) — Box fill calculations, device volume allowances, and equipment rating problems like the sample question above.
• Motors and Generators (34 questions) — Full-load current lookup, conductor sizing at 125%, overload protection sizing, and short-circuit/ground-fault protection selection using Table 430.52. This is one of the most heavily tested areas.
• Electrical Control Devices and Disconnecting Means (6 questions) — Disconnect ampere rating requirements and control circuit sizing.
• Special Occupancies, Equipment, and Conditions (6 questions) — Calculations specific to hazardous locations, health care facilities, and other special conditions covered in NEC Chapters 5 and 7.
• Renewable Energy Technologies (6 questions) — PV system current calculations, inverter sizing, and battery system requirements from NEC Article 690 and related sections.

Study Materials for the TX Master Electrician Exam

You really only need one book — but you need to know it inside and out.

NEC 2023 — Required

The National Electrical Code 2023 is the only reference you're allowed in the exam room, and it's the source for every question on the Calculations Portion. Owning the right edition matters — Texas requires the 2023 edition specifically. Make sure your copy is soft-bound; hardcover, spiral-bound, or ring-bound copies will not be admitted.

Before exam day, invest time getting familiar with the layout. Know where Articles 220, 230, 240, 310, 314, 430, and 690 live. Use the index. Practice flipping to tables quickly — in 170 minutes, speed matters.

You may highlight, underline, and add written notes to your NEC before the exam. Publisher-manufactured index tabs are permitted. Homemade tabs are not, and you cannot write in the book or add tabs during the exam session.

Study Tips for Master Electrician Calculations Exam Prep

Work through the exam once, then go back. On an open-book test, answer the questions you know first and flag the ones you don't. Then go back to the flagged ones. Don't sink 15 minutes into a single transformer problem while easy questions sit unanswered. Our practice exams let you bookmark questions for later review — same idea.

Practice in exam format. Our full practice exam matches the real PSI exam: same number of questions, same time limit, same topic breakdown. Practicing in that format means no surprises on test day.

Don't race. You have 170 minutes for 33 questions — that's more than 5 minutes per question. Other people finishing early is not your concern. Work at a steady pace, show your math, and review your answers before submitting.

Drill motors until they're automatic. Motor calculations (Articles 430 and the associated tables) show up repeatedly. If you can do full-load current lookups, conductor sizing, and OCPD selection without hesitation, you've cleared a major hurdle.

Know your formulas cold. The NEC doesn't include a formula sheet. You need to know the 3-phase power formula, the single-phase current formula, and the conduit fill process without hunting for them.

Frequently Asked Questions

How many questions are on the Texas Master Electrician Calculations Portion?
The Calculations Portion contains 33 total items, but only 30 are scored. The remaining 3 are non-scored pilot questions that don't count toward your result. You won't know which ones they are, so treat every question as if it matters.

How long do I have to complete the exam?
You have 170 minutes. One important detail: if you finish early, unused time does not carry over to the NEC Knowledge Portion. The two portions are timed independently.

What is the passing score?
You need to answer at least 70% of the scored questions correctly. That's 21 out of 30 scored items.

What does the exam cost?
The combined exam fee for both portions (NEC Knowledge and Calculations) is $78. If you fail one or both portions, the retake fee is also $78.

Is the exam open book?
Yes. You must bring your own soft-bound copy of the NEC 2023. The NEC 2023 is available on Amazon. Loose-leaf, spiral-bound, ring-bound, and the NEC Handbook are all prohibited.

Can I write in or tab my NEC?
You may highlight, underline, add written notes, and use publisher-made index tabs before the exam. You cannot add markings or tabs during the exam session, and homemade tabs are not allowed.

Can I use a calculator?
Yes — but it must be non-programmable, silent, battery-operated, and have no alphabetic keyboard or paper tape printing capability.

How do I schedule the exam?
After TDLR approves your eligibility, you'll receive instructions to schedule with PSI. You can register through the exam registration page, by phone at (833) 333-4741, or by mail. Visit the state licensing website for eligibility requirements.

What ID do I need to bring?
One valid government-issued photo ID — driver's license, state ID, or passport — that includes your printed name, photo, signature or fingerprint, date of birth, and expiration date. The name must match what's on file with TDLR.

What topics are covered?
The Calculations Portion covers ten areas: Calculations and Theory, Electrical Services and Separately Derived Systems, Electrical Feeders, Branch Circuit Calculations and Conductors, Electrical Wiring Methods and Materials, Electrical Equipment and Devices, Motors and Generators, Electrical Control Devices and Disconnecting Means, Special Occupancies, and Renewable Energy Technologies.

Ready to Start Preparing?

The Texas Master Electrician Calculations Portion is challenging — but it's designed to test skills you've been using on the job. With solid NEC knowledge, practiced calculations, and the right study approach, you can pass this on your first attempt.

Start with our free practice exam — 10 questions, no account required — to see where you stand. When you're ready to get serious, upgrade to the full practice exam for 178 questions, topic-by-topic scoring, and a format that mirrors the real PSI test. Get your NEC 2023 marked up and ready, and go earn that master electrician license.