National Electrical Code (NEC)
The model electrical safety code, published and updated every three years, that individual states and municipalities adopt, sometimes with local amendments, as the legal standard electrical work in their jurisdiction has to meet.
Why it matters
Nearly every specific electrical requirement discussed on a jobsite, from box fill limits to GFCI and AFCI placement to solar interconnection rules, traces back to a specific section of the NEC. Electricians and inspectors both work from the same code, which is what makes electrical inspection consistent and enforceable from one jurisdiction to the next.
On a real project
An electrician references the current NEC edition adopted by the local jurisdiction when planning a rough-in, since an older or newer edition can have different requirements for the same type of installation.
Who this matters most to
An Electrician works to the NEC on every job, and a building inspector checks electrical work specifically against the NEC edition the local jurisdiction has formally adopted.
Where this goes wrong
An electrician used to working in a jurisdiction on an older NEC edition takes a job in a jurisdiction that has already adopted a newer edition with stricter requirements, and plans the rough-in to the older rules out of habit. An inspector cites several code violations that wouldn't have been violations under the edition the electrician was used to.