Study Guides
Free in-depth guides covering electrical theory, NEC code articles, HVAC fundamentals, and exam concepts — with fully worked examples.
Plain-English breakdowns of the NEC articles tested most on licensing exams, with worked examples.
A deep, worked-example-driven guide to Article 250 — the grounding electrode system, GEC and EGC sizing logic, bonding jumpers, separately derived systems, and why ground rods alone never clear a fault.
A deep guide to NEC Article 210 branch circuits — circuit classifications, the 80% continuous-load rule with worked examples, multiwire branch circuits, dwelling outlet spacing, and dedicated appliance circuits.
A step-by-step walkthrough of NEC Article 220 dwelling and commercial load calculations, with six fully worked examples covering small, mid-size, and large homes plus a simplified commercial building.
A deep, plain-English walkthrough of NEC Article 240 — how fuses and breakers actually interrupt current, why conductors (not loads) get protected, standard device sizes, tap rules, panel schedules, and selective coordination, with worked examples for the exam.
A deep, plain-English breakdown of how GFCI and AFCI devices actually work inside, where each type of protection is required, and how to troubleshoot nuisance trips — with worked examples for the exam and the field.
A clear, from-first-principles explanation of how electrical service works — overhead vs underground, the six-disconnect rule, grounding at the service, and worked examples sizing both a residential and a commercial service.
A deep, plain-English walkthrough of NEC Article 300 — the general wiring method rules that govern every conduit run and cable installation, plus how EMT, IMC, RMC, PVC, NM, MC, AC, and UF actually compare in the field.
A deep, plain-English walkthrough of NEC Article 430 motor circuit rules — why motors need special sizing math, and how to size branch circuit conductors, short-circuit/ground-fault protection, and overload protection with fully worked examples.
Key formulas · NEC articles · Ampacity tables · Exam tips
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