Electrical Rough-In Inspection: What Inspectors Look For

The electrical rough-in inspection is one of the most critical milestones in any construction or renovation project. It occurs after all wiring is run through walls and ceilings but before drywall is installed, giving the inspector access to verify that the wiring meets code. Failing this inspection delays your project. Knowing what inspectors look for helps you prepare properly.

Wire Gauge and Breaker Sizing

Inspectors verify that wire gauge matches circuit breaker rating. The basic relationships: 15-amp breakers require 14 AWG or larger, 20-amp breakers require 12 AWG or larger, 30-amp circuits require 10 AWG, 40-amp circuits require 8 AWG. Using 14-gauge wire on a 20-amp breaker is a code violation and common inspection failure point.

Box Fill Calculations

Electrical boxes have maximum fill limits based on cubic inch volume. Too many conductors in a too-small box is a fire hazard and common violation. The 2020 NEC allows 2 cubic inches per 14 AWG conductor and 2.25 cubic inches per 12 AWG conductor. Inspectors count conductors and verify box volume. Switch loops, pigtails, and equipment grounding conductors all count toward fill limits.

Cable Stapling and Support

NM cable (Romex) must be stapled within 12 inches of every box and then every 4.5 feet along runs. Cables must be protected by nail plates where they pass through studs within 1.25 inches of the stud face. Cables across open framing must be stapled flat or run through holes drilled in the center of studs.

AFCI and GFCI Requirements

The NEC requires AFCI protection for circuits in bedrooms, living rooms, dining rooms, kitchens, laundry rooms, and most habitable spaces. GFCI protection is required for all bathroom, kitchen, garage, outdoor, crawlspace, and basement circuits. Inspectors verify the correct protection types are in place for each circuit’s location.

Grounding and Bonding

All metal electrical boxes must be grounded. Ground wires must be continuous — no breaks. The grounding electrode system (ground rods, water pipe connections) must be correctly installed. In panels, the neutral bus and ground bus are bonded together at the main panel only — not at subpanels.

Service Panel Wiring

Inside the panel, inspectors check that wires are correctly sized, neutrals and grounds are on the correct buses, double-pole breakers are used for 240V circuits, and there’s no double-tapping (two wires under one breaker terminal, unless the breaker is rated for it).

Check your box fill. Use the Box Fill Calculator on electricalcalcpro.com to verify your electrical boxes have adequate volume before your inspection.