Motor calculations on the Texas journeyman exam, and the split that decides most of the points

What the exam asks about motors

Motor work carries more weight on a Texas journeyman paper than its share of the code book suggests. In our 500 question bank, 43 questions sit in the motor and transformer calculation area, and another 18 reach a motor from somewhere else, so 61 of the 500 put a motor in front of you in one form or another. Those 18 arrive through the theory area, through the installation and grounding areas and through the Article 100 definitions, which means a candidate who files motors under Article 430 alone meets them again under headings they thought were settled.

The difficulty spread inside those 43 is worth knowing before you plan revision. Two sit at the easiest level, 12 at the second, 20 at the third and nine at the hardest, so the bulk of the area sits above the midpoint. That shape comes from the arithmetic being easy while the sourcing carries the work. Twenty-nine of the 43 carry numeric options, and in nearly every one of those the wrong options are correct arithmetic performed on the wrong current or with a multiplier borrowed from a neighboring rule.

Six of the 43 hand you both currents in the stem, and that is the question type to recognize on sight. A stem printing a nameplate figure and a table figure within an ampere or two of each other has already told you what it is testing.

The split that decides the answer

NEC 430.6 sets out which current feeds which calculation, and it is the section to read before anything else in the article. 430.6(A)(1) sends conductor ampacity, the ampere ratings of switches and the branch-circuit short-circuit and ground-fault protection to the full-load current table, selected by horsepower, voltage and phase. 430.6(A)(2) sends separate overload protection to the current marked on the motor itself.

Hold it as two jobs. Protecting the motor means reading the nameplate, because overload protection watches this particular machine and cares what it actually draws. Protecting the wire and the circuit means reading the table, because the code wanted a standardized figure that a designer and an inspector would arrive at independently without chasing a locked rotor value for every unit on site.

The disconnecting means sits on the table side of that split, which catches people who file it under equipment. A disconnect is a switch, and switches are one of the three things 430.6(A)(1) names. Ten of the 43 questions touch the disconnect and several are built on exactly that misfiling. The three devices on a motor circuit have a page of their own, because the exam asks the sourcing question and the device question separately.

The wrong answers people actually pick

Every question in our bank carries a line against each wrong option saying what a person who chose it did. Across the motor area those lines fall into four shapes, and recognizing the shape is faster than rechecking the arithmetic.

• The other current. The commonest by a distance. A candidate applies 125 percent to the nameplate when the conductor step wanted the table figure, or selects the overload off the table when 430.32 wanted the nameplate.
• The other multiplier. Three percentages land on the same motor in the same problem, and each wrong option is one of them applied correctly to the right current.
• A comparison no rule asks for. Options offering the average of the two currents, or whichever of them is larger, are written for a candidate who remembers that two figures exist and forgets that the code names one of them.
• The step that got skipped. A raw full-load current with no multiplier on it, or a base overload selection offered on a question whose stem says the motor would not start.

The third shape deserves a moment. One question sets the table value above the nameplate value on purpose, so a candidate who picks whichever is larger lands on the correct answer for the wrong reason, and then meets the same setup reversed later in the set.

Three multipliers, one motor

A single motor problem can call for three different percentages. 430.22 sets branch-circuit conductor ampacity at 125 percent of the table full-load current for a continuous duty motor. 430.110(A) sets the disconnect at 115 percent of that same table current. 430.52 caps the branch-circuit short-circuit and ground-fault device at a percentage running into the hundreds, chosen by motor type and by device type together.

A fourth multiplier appears on one narrow arrangement. Where a general-use switch acts as the controller for a stationary motor of 2 horsepower or less at 300 volts or less, 430.83(C) asks for a switch rated at least twice the motor full-load current, because that switch has to make and break starting current. A candidate who has drilled 115 and 125 into place will reach for one of those two and lose the point to a doubling.

Rounding runs in three directions

Three rules in one problem all talk about standard ampere ratings and they point different ways, which makes this a reliable place to drop a point.

• 430.52(C)(1) permits the next higher standard rating where the calculated branch-circuit device value misses one, with no conditions attached to the permission.
• 430.62(A) is a ceiling on the feeder device, so the answer is the standard rating at or below the calculated figure. Feeder sizing is where that reversal bites hardest.
• 240.4(B) permits rounding up in the general case only where all three of its conditions hold, and 240.4(C) requires the conductor to meet or beat the device above 800 amperes.

What moved in the 2026 edition

Texas examinations reference the 2026 National Electrical Code from 1 September 2026, adopted at 16 TAC 73.100, so the edition on the desk beside you is the edition the paper was written against. Three changes reach motor work.

• Article 404 lost the snap switches. General-use snap switches, dimmers and electronic control switches went to Article 406 under a new Wiring Devices title. Motor-circuit switches, isolating switches, pullout switches, molded-case switches and the enclosed general-use disconnect stayed behind in Article 404.
• 430.6(A)(1) tightened both of its equipment marking exceptions. The fan and blower exception now asks that the equipment nameplate marking be at least the current marked on the fan or blower motor itself, and the appliance exception now asks for horsepower and full-load current together on a listed motor-operated appliance, where the 2023 text asked only for a motor type marking.
• 430.24 gained a conductor temperature provision for Design BE and CE motors, which is where those designations enter the article.

The section template the 2026 edition ran through the book is better learned as a pattern than as a list of moved numbers. Listing requirements went to .2 of an article and reconditioned equipment to .3, and whatever had been sitting in those slots moved down. The best known casualty sits in the transformer article, where overcurrent protection left 450.3 for 450.5, and a tab reading 450.3 now opens on a heading whose subsections are marked reserved. An occupied wrong number costs more time than a vacant one, because it reads as though you are in the right neighborhood.

What this costs on the job

Two of the bank questions describe failures that surface in the field long after the paper is marked.

The first is a motor swap. Horsepower and voltage are what you carry into the table, so a replacement of the same rating leaves the conductors, the disconnect and the short-circuit device exactly where they were. The nameplate current can still differ, and 430.32 selects the overload from the nameplate, so a swap that looks identical on paper can leave the old overload sitting at the wrong percentage of the new winding. Everything about the installation looks unchanged while the protection has quietly moved.

The second is a disconnect that misses by an ampere. A 27 ampere table current asks for 31.05 amperes under 430.110(A), and a 30 ampere general-use switch falls short of it. That is the margin that gets waved through on site because the two numbers look close together, and it is the margin an inspector checks with a calculator. A rejected disconnect on a rooftop unit buys a return trip, a re-inspection and a conversation with a general contractor about the schedule.

Voltage drop carries a third cost that candidates underrate. Motor torque follows the square of the applied voltage, so a motor starting on 92 percent of nominal develops about 85 percent of its rated starting torque. A machine that cannot accelerate its load keeps drawing starting current, which deepens the drop that caused the trouble, and the condition feeds itself until the overload device opens.

What to do before test day

The Texas examination is open book and you bring your own copy, so none of this is a memory exercise. What you are rehearsing is the order of operations and the sourcing.

1. Write both currents at the top of your scratch paper and label them before you start. Table on the left, nameplate on the right. Every step afterward points at one column.
2. Add a line above them naming the kind of motor. Motors built for low speeds under 1200 RPM, motors built for high torques and multispeed motors are excluded from the table by the opening words of 430.6(A)(1), and two marked-equipment exceptions hand the whole branch circuit to a marked current.
3. Tab 430.6, 430.22, 430.32, 430.52, 430.62 and 430.110. Six tabs cover the great majority of the 43 questions in this area.
4. Work a set against a clock. The thirty free questions here are timed and show the section behind every miss, which is the part that changes how you read the next stem.

For the same steps with the figures filled in line by line, the question sets carries the motor calculation page, which is where the worked arithmetic lives.

Questions people ask

How many motor questions should I expect on the Texas journeyman exam?

We can only tell you what our own bank looks like, because every question we publish is original and none of them come from a live exam. In our 500 question bank, 43 sit in the motor and transformer area and another 18 reach a motor through theory, installation, grounding or the definitions. That is 61 of 500, or a little over one question in eight. Treat that as a guide to how much revision the topic deserves, and check the current PSI candidate information bulletin for the published outline weighting on the examination you are booked for.

Which current sizes the conductors on a motor branch circuit?

The table full-load current, selected by horsepower, voltage and phase. NEC 430.6(A)(1) names three things that come from the table: conductor ampacity, the ampere ratings of switches, and branch-circuit short-circuit and ground-fault protection. The nameplate current is held back for the overload device under 430.6(A)(2). Order matters as much as sourcing here. Pick the current first, then apply the multiplier, because a candidate who applies 125 percent to the nameplate has done correct arithmetic on the wrong input and will find that answer waiting among the options.

Is the motor disconnect sized at 115 percent or 125 percent?

115 percent, under NEC 430.110(A), applied to the table full-load current. The 125 percent belongs to the branch-circuit conductors at 430.22 and it sizes wire. One bank question puts a 30 ampere switch on a motor with a 27 ampere table current, which needs 31.05 amperes and fails by a single ampere, and it offers 33.75 amperes as the trap for anyone who reached for the conductor multiplier. Where one disconnect serves a group that can all run together, 430.110(C) sums the full-load currents first and then applies the 115 percent to the total.

When do branch-circuit conductors come off the nameplate?

On a motor whose duty is short-time, intermittent, periodic or varying. NEC 430.22(E) applies its duty-cycle percentages to the nameplate current rating, which makes it a genuine exception to the pattern the rest of the article follows. It changes two things at once, the multiplier and the current the multiplier acts on, so mark it in your book as the place where conductors read the nameplate. Any motor application counts as continuous duty unless the machine it drives is unable to run continuously under load, so the classification describes the driven equipment.

Which code edition will my Texas exam be written against?

The 2026 National Electrical Code, for examinations from 1 September 2026, adopted statewide at 16 TAC 73.100. Texas adopted the edition with at least one amendment inside it, so a nationally written summary can be correct everywhere else and wrong here. The examination is open book and you bring your own current copy. Nothing about your license term or renewal date moves with the edition, and there is no filing or fee attached to the adoption, so the change shows up in your study material and in your next continuing education course.

Do I need to memorize the full-load current tables?

No. The examination is open book, the tables are in the code you carry in, and time spent memorizing them buys nothing. What repays practice is the sequence: decide whether the table covers this motor at all, pick the current, apply the multiplier that belongs to the step you are on, then round in the direction that step allows. Candidates lose points on the motor area by working straight down a remembered list without noticing that step three changes source current, and no amount of table recall repairs that.