Electrical Load Case Studies

Electrical Load Case Studies is a hands-on engineering companion for designers, students, and apprentices learning electrical distribution. Instead of static reference pages, every calculation walks you through each step with the NEC article it cites — so you build judgment, not just answers.
Whether you're sizing a residential service, sanity-checking a feeder before submittal, or studying for a code exam, you have the working tools and the reasoning behind them in one place.
CALCULATORS
• Residential service load — both the standard method (NEC 220 Part III) and the optional method (220.82). Editable inputs for square footage, small-appliance and laundry circuits, fixed appliances, range, dryer, HVAC noncoincident loads, and EV chargers. Every demand factor is shown with the article it comes from.
• Commercial service load — unit-load by occupancy, receptacle demand factor, motor branch sizing, continuous-load adjustment.
• Conductor & breaker sizing — adjusts 90°C ampacity for ambient temperature and bundling, enforces 110.14(C) terminal limits and 240.4(D) small-conductor caps, picks the next standard OCPD per 240.6(A).
• Voltage drop — branch and feeder, single-phase or three-phase, with an automatic upsize suggestion when drop exceeds 3%.
• Box volume fill — Table 314.16(B) per-conductor volume, with proper handling of devices, clamps, support fittings, and grouped equipment grounds.
CASE STUDIES
Three progressive worked examples — single-family dwelling, six-unit multifamily with 220.84 diversity, and a small commercial tenant build-out. Each includes a scenario brief, load schedule, single-line representation, decision-point quizzes that explain the reasoning behind each choice, and a one-tap link into the live calculator with the values pre-loaded.
CODE BROWSER
Searchable summaries of the NEC articles you actually use — 220, 230, 240, 250, 310, 314, 625, 705 — with plain-English explanations and a "common mistakes" list for each.
SCENARIO SIMULATOR
Take a finished residential calculation and layer on a real-world change: add a Level-2 EV charger, convert AC to a heat pump, add an ADU, or test a PV interconnection against the 705.12 120% rule. See the before/after demand, line current, and required service size side-by-side.
PRACTICE MODE
Self-assessment problems with numeric answer fields, tolerance-based grading, and full worked solutions when you want to compare your work line-by-line.
DIAGRAMS
22 reference illustrations covering services, branch wiring, grounding systems, and motor circuits, with pinch-zoom viewing.
EXPORT
Generate a project-ready PDF of any calculation — header, summary, full step-by-step trace, NEC references, footer disclaimer — sized for letter paper and ready to share, file, or print.
Educational tool. NEC values reflect common 2023 NEC practice; verify against your codebook and have all designs reviewed by a licensed engineer before installation.