Residential wiring, in brief

Background reading. Jeffrey’s current work, as listed on his resume, is commercial. This page does not say he wires houses for a living.

Houses are usually wired in nonmetallic sheathed cable, with a 120/240-volt single-phase service. Commercial buildings are usually conduit or cable assemblies at 480Y/277, with a separate 208Y/120 system for receptacles. The habits do not copy straight across.

Device circuits in dwellings have required locations: kitchens, bathrooms, outdoors, garages, and other rooms named in the adopted NEC. GFCI and AFCI protection have grown with each code cycle. The city’s adopted year is the list that matters.
Box fill (Article 314) counts conductors, devices, clamps, and grounds. A crowded box is a heat problem and a code problem.
A dwelling service disconnect is not permitted to be smaller than 100 amperes under the usual reading of 230.79. Load calculations for a house live in Article 220, and the 2026 NEC reorganized some of that material. Do not quote a volt-per-square-foot number without naming the code year.
The neutral and the equipment ground bond at the service, and not at a subpanel. That rule is the same idea as on the grounding page.

The useful crossover from commercial work is the discipline: read the print, support the cable, torque the device, label the panel, and do not work in a live box because it is a house.

Code section numbers, energy-code rules, and utility practices change by edition and by city. The authority having jurisdiction, and the employer’s written program, decide what applies on a given job.