Electrician Exam Calculation Ladder
Eight rungs in the order the exam gets harder, box fill on the first rung and tap conductors on the last, ten problems on each one with the arithmetic shown line by line after you answer. Every rule is cited to the 2026 National Electrical Code.
The Michigan examinations reference the 2023 National Electrical Code, and the state enforces the same 2023 edition with the Michigan amendments. This page holds 2026 table values, so check anything you rely on against your own 2023 copy.
Chapter 9 is still the tables in both editions, so the tables this page uses carry the same numbers in a 2023 book, and Annex C is still Annex C. Ampacity is still Article 310 and overcurrent is still Article 240 in both editions, so Table 310.16, the 310.15 correction and adjustment tables, 110.14(C) and 240.4(D) carry the same numbers in a 2023 book. Two rungs name numbers that moved: the transformer rung, where 450.3 became 450.5, and the dwelling service rung, where the load calculations moved from Article 220 to Article 120.
Get one worked question a week, the same style as these rungs. One original question in the Michigan style, the arithmetic shown, and a line on each wrong answer naming the mistake that produces it.
Box fill is one addition against one table value, so it is where the method shows up with nothing else in the way. Conduit fill adds a second table and a rounding rule, voltage drop adds a formula, derating adds two factors and a cap, and by the time you reach the service calculation you are running six rules in sequence and any one of them can lose the mark.
The practice exam mixes all of this to the mix this site sets. The ladder does the opposite on purpose: one calculation at a time until that one is not the problem any more.
How the ladder works
Pick a rung and it gives you ten problems, one at a time, four numeric options each. Answer and the page prints the whole calculation, step by step with your numbers substituted, plus the section it comes from and one sentence naming the trap that particular problem is built around.
Seven right out of ten opens the rung above. Fewer than seven and the rung stays where it is, which is the point: the ladder is not trying to be generous, it is trying to be a floor you can stand on.
Progress lives in this browser under a key starting with txee, so there is no account and nothing to log into. Clear the browser and the ladder starts again at rung one, and the paid rungs come back with the get it back link.
Rung one ships inside the page and needs no network at all. Rungs two to eight are fetched once from this site's own server when the browser holds a paid token, and then they run in the page the same way.
What each rung tests
| Rung | What it asks | Cited to |
|---|---|---|
| 1 | Box fill. Required volume for a box, with the count rules for clamps, yokes and grounding conductors | 314.16(B)(1) through (B)(5), Table 314.16(A), Table 314.16(B)(4) |
| 2 | Conduit fill. Largest count that fits a raceway, and percent fill for a given count | Chapter 9 Table 1 and its Notes 3, 4 and 7, Table 4, Table 5 |
| 3 | Voltage drop. Volts dropped and percent of source, single-phase and three-phase | Chapter 9 Table 8, with the note figures at 210.19 and 215.4(A)(2) |
| 4 | Ampacity derating. Ambient correction, conductor count adjustment, then the termination cap | 310.15(B)(1), 310.15(C)(1), 110.14(C), Table 310.16 |
| 5 | Motor conductors and overload. Conductor ampacity, overload setting, and the largest branch circuit fuse | 430.6(A)(1), 430.22, 430.32(A)(1), Table 430.52(C)(1) |
| 6 | Transformer current and protection. Primary and secondary current, and the primary device allowed | 450.5(B), Table 450.5(B) and its Note 1, Table 240.6(A) |
| 7 | Dwelling service, standard method. Total calculated load for a one-family dwelling, standard method | 120.41, 120.45, 120.52, 120.53, 120.54, Table 120.55, 120.6 |
| 8 | Tap rules. Minimum tap conductor ampacity under each of the three tap rules | 240.21(B)(1), 240.21(B)(2), 240.21(B)(3) |
The 2026 renumbering, in two lines
Load calculations were Article 220 for as long as most of us have been reading the book and they are Article 120 in the 2026 edition. Rung seven is worked against 120.41, 120.45, 120.52, 120.53, 120.54 and Table 120.55, and the dwelling unit load in 120.41 is 2 volt-amperes per square foot rather than the 3 that older material prints.
The 3 volt-ampere figure did not disappear. It sits at 120.13 and it sizes branch circuits, which is a different question from sizing a service, so reaching for it out of habit inflates a service calculation by half. Transformer overcurrent protection moved the same way, from 450.3 to 450.5, and rung six cites the section that is actually in the 2026 book.
Questions people ask
What is on the calculation ladder?
Eight rungs in the order the exam gets harder: box fill, conduit fill, voltage drop, ampacity derating, motor conductors and overload, transformer current and protection, the dwelling service load by the standard method, and tap rules. Each rung holds ten problems with different given values, and each one shows the working line by line once you answer.
How do you open the next rung?
Seven right out of ten opens the rung above it. The score is kept in this browser, so the ladder remembers where you got to without an account. Rung one is free and works with no network at all.
Which code edition do the answers use?
The 2026 National Electrical Code. That matters most on the service calculation, which moved from Article 220 to Article 120 and now sets the dwelling unit load at 2 volt-amperes per square foot under 120.41, and on transformer protection, which moved from 450.3 to 450.5.
Is the ladder included with the practice exam purchase?
Yes. One payment of $79 opens the question bank on the practice page and all eight rungs here. If you have already paid, use the get it back link and the same email you paid with.
Why does the ladder show the arithmetic instead of just marking the answer?
Because the marks go to the method rather than to the number. Almost every wrong answer on these rungs is a step taken out of order or a factor left out, and you cannot see which one it was from a red cross.
The 2023 to 2026 section crosswalk maps every section that moved, both directions, $29 once.
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