An inspector who red-tags your rough-in is not making a point. The work did not meet code, and code is the floor, not the target. What makes it frustrating is how repetitive the failures are. The same handful of violations turn up on residential jobs year after year, in new construction and in remodels, and almost all of them cost more to fix after drywall than they would have cost to do right the first time.

This walks through the five NEC violations that show up most often on residential electrical inspections, why each one fails, and what it costs you when it does.

One note before the list. NEC adoption is not national. States and municipalities adopt on their own schedule, and plenty are still enforcing the 2017 or 2020 cycle while others have moved to 2023 or 2026. The article numbers below are stable across recent cycles, but the specific requirements have tightened in places. Verify against the code your AHJ actually enforces, not the newest book on the shelf.

1. Box fill violations

The most common citation in residential rough-in, and the one most likely to be dismissed as nitpicking right up until you have to open a wall.

The rule: NEC 314.16 sets the maximum number of conductors permitted in a box based on the box's cubic inch volume and the size of the conductors. Every current-carrying conductor counts. So does the equipment grounding conductor, but all grounds together count as one. Each device such as a receptacle or switch counts as two conductors at the size of the largest conductor connected to it. Internal cable clamps count as one.

Why it fails: Nobody does the arithmetic. A standard single-gang plastic old-work box runs somewhere around 14 to 18 cubic inches, and a 14 AWG conductor requires 2 cubic inches while a 12 AWG requires 2.25. Add a three-way switch to a box that already has two cables plus a ground and a clamp, and you are over before you notice. Remodel work is worse than new construction, because you inherit whatever box the last guy installed and then add to it.

How to avoid it: Size the box for the finished device count, not the rough-in count. If a room might get a dimmer, a smart switch, or a second three-way later, the extra dollar for a deeper box now is the cheapest insurance on the job. When you inherit a box, count before you add.

2. Cable support and securing

The rule: NEC 334.30 requires NM cable to be secured within 12 inches of every box with a cable clamp, and supported at intervals not exceeding 4.5 feet. Boxes without cable clamps have their own allowance, but the 12 inch rule is the one that gets missed.

Why it fails: Speed. Stapling is the least satisfying part of a rough-in and it is the easiest to leave for later, and later does not come. Long runs across a basement ceiling or through an attic get pulled, land in the box, and never get stapled at all. The inspector does not have to look hard.

How to avoid it: Staple as you pull, not after. Running the whole house and then going back to secure is how runs get missed, because by then you cannot see which cable you already did.

3. Missing physical protection where cable passes through framing

The rule: NEC 300.4(D) requires that cables run through bored holes in studs or joists be kept at least 1.25 inches from the nearest edge of the framing member. Where that distance cannot be maintained, a steel plate or bushing at least 1/16 inch thick has to protect the cable.

Why it fails: The 1.25 inch clearance is measured from the edge of the hole, not the center, and a 2x4 is 3.5 inches deep. Center a hole and you have room. Drill it slightly off, or notch instead of bore, or run through a furring strip or a doubled stud where the geometry is different, and you are inside the line. Notching almost always requires a plate.

How to avoid it: Keep nail plates in the pouch and use them whenever you are close. A plate costs pennies. A drywall screw through a hot conductor is a callback at best.

4. Neutrals and grounds bonded in a subpanel

The one on this list that is an actual safety defect rather than a technicality, and the one most likely to have been done wrong by whoever came before you.

The rule: The grounded conductor and the equipment grounding conductor are bonded together at exactly one point, the service disconnect. In a subpanel, neutrals land on an isolated neutral bar and grounds land on a separate grounding bar bonded to the enclosure. The bonding screw or strap that ships with the panel comes out.

Why it fails: Subpanels ship from the factory with the bonding means included, and installing the panel without removing it is the path of least resistance. It also fails because the panel looks fine and works fine. Nothing trips. The defect only shows itself when normal neutral current starts returning on the equipment grounding conductor and on any metal path bonded to it.

How to avoid it: Make removing the bonding screw part of setting the panel, before you land a single conductor. When you open an existing subpanel for any reason, look at the bars. This is a common enough legacy defect that finding it is a service opportunity, not just a code note.

5. Working space at panels

The rule: NEC 110.26(A) requires clear working space in front of equipment likely to require examination or servicing while energized. For most residential panels that means 36 inches of depth, a width of 30 inches or the width of the equipment if greater, and a height of 6.5 feet or the height of the equipment. The space stays clear. It is not storage.

Why it fails: Panel location is usually decided by someone else, often before the electrician is on site, and the consequences do not appear until the finish trades arrive. A panel that passed rough-in gets a water heater, a shelving unit, or a furnace installed in front of it.

How to avoid it: Raise it at panel location, in writing, before it is set. If the homeowner or builder wants the panel in a spot that cannot hold the clearance, that conversation is far cheaper before the panel is mounted than after the basement is finished.

The cost of a citation

A failed inspection is rarely just the fix. It is a return trip, a reinspection fee in many jurisdictions, and a hole in your schedule that you cannot fill on short notice. If the failure lands after drywall or after finish, add the repair of whatever has to be opened up and closed back in.

The part that is harder to price is what it does to the relationship. A general contractor whose schedule slipped because your rough-in failed remembers it. So does a homeowner who took a day off work for an inspection that did not pass.

The honorable mentions

These come up often enough to be worth a second look before you call for inspection.

AFCI and GFCI coverage gaps. The required locations under 210.8 and 210.12 have expanded in nearly every recent cycle. If you are working from what the code required when you learned it, you are almost certainly short somewhere.

Tamper-resistant receptacles. NEC 406.12 covers more locations than most people assume, and a standard receptacle in a required TR location is a cheap fix found late.

Termination torque. NEC 110.14(D) requires that terminations be tightened to the manufacturer's specified value where one is provided. Some inspectors ask to see the torque tool.

Unused openings. Open knockouts in panels and boxes are an easy walk-by citation and take seconds to close.

Why this matters for pricing

Failed inspections are an unpriced cost that comes straight out of your margin, and most contractors never see it because it never gets recorded against the job. The return trip is billed to nobody. It shows up as a day that felt busy and did not produce revenue.

If you are tracking job profitability, callbacks and reinspections deserve a line. Once you can see what they cost you across a year, the case for buying deeper boxes and keeping nail plates in the pouch stops being about code compliance and starts being about money.

The bottom line

None of the five is difficult. Every one of them is a habit rather than a skill. Box fill is arithmetic you do once at rough-in. Stapling is something you do while you pull instead of after. Nail plates are in the pouch or they are not. The bonding screw comes out when you set the panel. Panel location gets raised before it is mounted, not after.

Inspectors are not the adversary. They are the last check between your work and somebody's family, and the same five items keep appearing because they are the ones easiest to leave for later.

Frequently Asked Questions

Which NEC edition does my inspector actually enforce?
Whatever your state or municipality has adopted, which is often one or two cycles behind the current code. Adoption is set at the state level in most places and can be modified locally. Call the AHJ before you assume, particularly if you work across county lines.

Does box fill count the ground wires individually?
No. All equipment grounding conductors in a box together count as a single conductor volume allowance, sized to the largest ground present. Devices are what surprise people. Each yoke counts as two.

Can I ever leave the bonding screw in a subpanel?
Only if that panel is functioning as the service disconnect. In a true subpanel fed from an upstream service, the neutral has to be isolated. A detached structure fed by a feeder has its own rules worth reading directly rather than working from memory.

Is a notch in a stud always a violation?
Not automatically, but a notched framing member rarely leaves 1.25 inches of clearance, so a steel protection plate is almost always required. Framing members also have their own structural limits on notching under the building code, separate from the NEC.

Do nail plates need to be a specific thickness?
NEC 300.4(D) calls for a steel plate or bushing at least 1/16 inch thick. Standard plates sold for the purpose meet this. Verify anything unusual.