Electrical Code and Plan Review Fundamentals
What this domain tests
Plan review is about reading a drawing set the way an inspector will: finding the service, the panel schedules, the load calculations, the grounding details, and the notes that govern them. Candidates must know how the code is organized (articles, parts, tables, exceptions), how to apply the mandatory and permissive language, and how to trace a plan from the utility connection through the distribution equipment.
Concepts to master
- Code structure and hierarchy: articles, parts, sections with numbering that tells you the article (e.g., a section number beginning 2xx belongs to Chapter 2).
- Chapter map: Chapter 1 definitions and general rules; Chapters 2-4 wiring and protection; Chapters 5-7 special occupancies, equipment, and conditions; Chapter 8 communications; Chapter 9 tables.
- Mandatory vs. permissive language: "shall" is required, "shall not" is prohibited, "may" is permitted.
- Drawing set components: cover sheet, symbols legend, one-line diagram, panel schedules, load calculation worksheets, fault-current information, and installation notes.
- Plan review workflow: verify scope, check service and feeder sizing against calculated load, confirm conductor and overcurrent protection coordination, confirm grounding and bonding details, then check special occupancies.
Traps in questions
Questions often test the difference between a code requirement and a design preference, or between the minimum code and a local amendment. Another common trap is a plan that is internally inconsistent - the panel schedule sums to more than the feeder ampacity - and the question asks which item is the violation. Read for the specific code section cited, not the general principle.
Rule of thumb
When reviewing any plan, start at the service and work downstream: service size, feeder, panel, branch circuits, then devices. Most review findings are mismatch errors along that chain, not obscure code sections.
Worked example
A plan shows a 200 A service with a 4/0 aluminum feeder to a 200 A panel. The calculated load is 165 A. The feeder and panel are adequate; the review point is whether the calculated load documentation is attached and whether the neutral and grounding electrode conductor sizes match the service conductors.