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Every Exam Formula.
One Page. Free.
The Sparky NEC formula sheet: every calculation the journeyman electrician exam can throw at you — with worked examples — on a single page. Tape it inside your Code book cover and drill it until it's reflex.
Based on the 2023 NEC · Built by a master electrician
What's on it
Formulas to Memorize. Tables to Look Up.
The exam is open-book — but the clock isn't. The calculations in Section D are where test-takers bleed time, because they flip through the book for things they should know cold.
This sheet splits the difference: memorize the 12 formulas, and memorize where the tables live so every lookup takes seconds.
One page. Burn the formulas in — everything else lives in your Code book.
Testing on the 2026 NEC? The formulas don't change between editions — and inside the Sparky app you pick your edition (2023 or 2026) when you start, so every drill and tab reference uses the right numbers for yours.
Single-phase and 3-phase, with worked examples.
125% / 115% rules, nameplate vs. table amps.
The 83% rule and the 40% remainder shortcut.
The 12.9 constant, 53% / 31% / 40% fills.
All 12 P-I-E-R combinations at a glance.
240.4(D), 250.66, 310.16, 314.16, 430.52, Ch. 9 — know where, not what.
FAQ
Frequently Asked Questions
Is the formula sheet really free?
Yes. Download the PDF — no signup, no email required.
Which NEC edition is it based on?
The sheet itself follows the 2023 NEC — but the formulas don't change between editions. And inside the Sparky app, you pick your edition (2023 or 2026) when you start, so every drill and tab reference uses the right numbers for yours.
Can I bring it into the exam?
No — testing centers don't allow outside notes. This sheet is for studying: memorize the formulas, and use your tabbed Code book for everything else on test day.
Formulas memorized? Now drill them.
The sheet is the what. Sparky is the reps — 1,087 codebook-first questions, 15 minutes a day.
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