One real building — a 5-story, 120,000 sq ft office on a 480Y/277V service — carried through all 8 stages of commercial electrical design, in the order a working engineer actually uses them. Every step links to a real calculator on the site.
8 steps, from load calculation to a finished, phase-balanced panel schedule. Steps 1-2 are free. Steps 3-8 unlock with a one-time $4.99 purchase.
Lighting, receptacle, HVAC, and elevator load, combined into a single building demand figure per NEC Article 220.
Turning the calculated demand into a main switchboard selection, with real spare-capacity margin.
Sizing floor feeders, the chiller feeder, and the elevator feeder per NEC 310.15 ampacity and conduit fill.
Checking every feeder against voltage-drop design targets, not just ampacity.
Point-to-point fault current at the main switchboard and every floor panel — the number every downstream device rating depends on.
Verifying a downstream fault trips only the nearest device, using time-current curves.
Incident energy, arc-flash boundary, and required PPE category at every study point, per IEEE 1584 and NFPA 70E.
The finished, phase-balanced panel schedule — every prior step made visible in one document.
Educational project reference. This project walks through a realistic scenario using the site's real calculators and written guides — it is a learning and reference resource, not a permit-ready construction document. Final system design, code compliance, and installation require a licensed engineer or contractor. See our full disclaimer.