Commercial electrical work spans two related but distinct skills: designing a code-compliant system from the ground up, and reading, verifying, or troubleshooting a drawing set that someone else produced. This comprehensive guide teaches both, combining a complete commercial electrical design methodology with a full construction-drawing-literacy course in one reference. Starting with codes, standards, and power distribution fundamentals, this book walks through reading and producing key plans, floor plans, electrical plans, and wiring layouts; NEC Article 220 load calculations including lighting, receptacle, HVAC, show window, and sign circuit loads; conductor sizing and the nine-step feeder sizing procedure; panel schedule development; voltage drop analysis; and construction documentation standards. Five fully worked case studies anchor the material in real design work. Two multi-tenant retail buildings are developed at different scales -- a 10,400-square-foot strip mall with 200A tenant panels and rooftop HVAC loads, and a compact three-unit tenant building with 20-50A panels and branch-circuit-level derating detail -- so readers see the same methodology applied at both ends of a real practice. A full-service restaurant introduces concentrated kitchen equipment loads. A medical office building applies NEC Article 517 essential electrical system requirements. And a multi-building corporate campus scales the methodology up to medium-voltage distribution, emergency power, and UPS-protected critical loads. Appendices provide a conductor ampacity reference, a combined symbols and abbreviations guide, a common design errors checklist, a comprehensive glossary, practice questions, and a master drawing index -- built for daily use on the job.