Hide Romex Behind Drywall (Surface Raceway)
You can conceal NM-B cable inside a wall cavity, or run approved conductors in a listed surface-raceway system. These are different methods: surface raceway stays exposed and must not be buried behind drywall. Plan the route, protect cable at framing, secure it as required, and keep every box and splice accessible. Local code, permits, and inspections may add requirements.
A mounted TV can look finished until a cable drops from its outlet to the screen. The fix is not simply to cover the wire. The right method depends on whether you want wiring inside the wall or contained in a visible channel on its surface.
I have seen homeowners use “raceway” to mean any path for a cable, but electrical rules treat wiring methods differently. The key decision is simple: use NM-B cable in a suitable wall cavity, or choose a listed surface-raceway system and install it as the manufacturer and code allow. Do not install a surface raceway and then bury it in drywall.
Plan the Route and Confirm the Wiring Method
A wiring method is the approved way to carry and protect electrical conductors. Before cutting drywall or buying materials, decide whether the cable will run inside the wall or the raceway will remain visible. Check the local code edition, permit rules, and inspection needs before starting.
For a concealed route, NM-B cable, often called Romex, may run within a wall cavity when installed under applicable rules. For a surface route, use a listed raceway system with compatible fittings and conductors. A surface raceway is designed to remain accessible on the wall, not to become a hidden wall cavity.
Survey the route before opening the wall
Identify the circuit, its source and destination boxes, the framing, and any likely obstructions. A stud finder can help locate framing, but it does not confirm that a wall is free of pipes or wiring. Review accessible plans or inspect from an attic, basement, or existing opening where possible.
Confirm which breaker supplies the circuit, then verify the circuit is de-energized with a suitable tester before work begins. If you cannot identify the circuit, confirm it is off, or safely access the route, stop and call a qualified electrician.
Do not use a wall cavity as a shortcut for an extension cord or a loose power strip. For fixed building wiring, use an approved wiring method and code-compliant connections. If the project involves adding or moving a receptacle, check permit requirements and have the work inspected as required.
| Goal | Appropriate route | Important limit |
|---|---|---|
| Hide fixed wiring in a wall | NM-B in a wall cavity, where permitted | Support, protect, and terminate it under applicable rules |
| Cover a wire on the wall surface | Listed surface raceway | Keep it exposed and use its compatible parts |
| Hide an existing raceway behind new drywall | Neither method | Do not bury the raceway, its cover, or a box |
Choose between concealed cable and exposed raceway
Concealed NM-B gives a clean wall, but it may require access through drywall and careful drilling through framing. A surface raceway avoids opening the wall, but its channel and cover remain visible. Paintability and color options depend on the product, so check the manufacturer’s instructions.
The choice is not just about appearance. It also affects what materials you can use, how the route is supported, and whether future access is possible. A raceway’s listing states what it can contain and how it must be installed; do not assume any cable fits any raceway.
Check Framing Setbacks, Box Access, and Clearances
Framing setbacks protect cable from nails and screws that may enter the wall later. Box access keeps splices and terminations available for inspection or repair. These details matter whether a route is part of a larger renovation or a small cable change behind a TV.
For holes through wood framing, NEC 300.4(A)(1) generally requires the nearest edge of the hole to be at least 1¼ inches (32 mm) from the nearest edge of the framing member. If that spacing cannot be maintained, the code calls for an approved steel plate or equivalent protection as specified. Confirm the adopted code and local amendments.
Protect and support NM-B cable
Drill through the center area of the framing when the route allows. Measure the setback from the edge of the hole to the nearest face of the stud or joist, not from the cable itself. Where the required distance is not possible, install the prescribed steel protection plate so later fasteners are less likely to hit the cable.
NEC 334.30 generally requires NM-B to be secured within 12 inches (300 mm) of boxes, cabinets, or fittings and supported at intervals no greater than 4½ feet (1.4 m), subject to exceptions in that section. Use cable supports made for the job, and do not crush or damage the sheath. Follow the cable maker’s guidance as well as code.
Keep boxes and splices accessible
A junction box is an enclosure where conductors connect or branch. Under NEC 314.29, boxes must remain accessible without removing building finish or structural parts. Do not cover a box, splice, or outlet with drywall, trim, or another permanent finish.
Plan the cable route so the box stays visible and reachable after the wall is finished. A cover plate may be neat and paintable, but it still needs to be removable. If a box location will be behind a fixed cabinet, built-in panel, or mounted display, consider whether it will remain accessible in practice and meets local requirements.
There is no general CFM or ventilation requirement for ordinary NM-B concealed in a wall cavity. The cavity is not a ventilation duct, and a raceway is not an air duct. Do not add vents or treat airflow as a substitute for using the correct wiring method.
Install Concealed NM-B or Exposed Surface Raceway
Installation steps depend on the chosen method and product. Concealed cable belongs in the wall cavity; a surface raceway remains on the wall. Follow the adopted electrical code, the raceway listing, and manufacturer instructions, and do not improvise a route that hides covers or splices.
Route NM-B inside the wall cavity
With power confirmed off, open only the wall area needed to reach the framing and boxes. Check the cavity for obstructions before drilling. Make holes that preserve the framing setback, then feed the cable without scraping, kinking, or stretching its sheath.
Secure the cable at required points and protect it where the framing setback cannot be maintained. Keep connections inside approved boxes. Do not leave a splice loose in the wall, and do not cover a box with the new drywall. Before closing the wall, check the full route and photograph it for future reference.
Mount a listed surface-raceway system
Select a product listed for the intended use and route. Use the system’s compatible channel, cover, fittings, and conductors, and follow its instructions for mounting and fill limits. The product’s listing and applicable raceway rules determine what can be installed inside; NM-B is not a general-purpose set of raceway conductors.
Keep the raceway exposed and accessible after installation. Do not place drywall over its channel or cover, even if the result looks smoother. If the raceway must cross a corner, enter a box, or change direction, use fittings approved for that system rather than making an unlisted joint.
| Installation point | Concealed NM-B | Exposed surface raceway |
|---|---|---|
| Location | Inside suitable wall cavity | Mounted on finished wall |
| Cable or conductors | NM-B, where permitted | Only types allowed by the listing and code |
| Framing protection | Maintain 1¼-inch setback or provide required protection | Follow system instructions and applicable rules |
| Access | Boxes and splices remain accessible | Raceway and boxes remain accessible |
| Before finishing | Inspect support, protection, and box locations | Do not cover with drywall or permanent finish |
Inspect, Close, and Verify the Installation
An inspection before drywall is your last clear chance to see the concealed route. Check that cable is supported, framing protection is in place where needed, and every box is positioned to remain accessible. After finishing, confirm that the work has not damaged or covered wiring or boxes.
Before closing a wall, compare the installation with the route plan. Look for exposed cable sheath damage, loose cable, missing protection plates, and boxes that will be hidden by the finish. Arrange any required inspection before covering the work; local rules determine when an inspector must see it.
After drywall and paint, verify that receptacles and covers are secure and that all boxes remain accessible. If the work added or changed a circuit, required tests and inspections depend on the work and local rules. Do not energize wiring if you see damage, have an uncertain connection, or lack confidence in the installation. Ask a qualified electrician to inspect it.
Two common project scenarios
These examples are illustrative, not reports of specific jobs. They show how the method changes with the wall and the desired finish.
- TV on a framed interior wall: The homeowner wants no visible power cable. A concealed NM-B route may be suitable if the circuit, boxes, framing path, support, and protection meet local rules. Before drywall closes, the cable and accessible box locations can be checked.
- TV on a finished wall that should not be opened: The homeowner wants to avoid cutting drywall. A listed surface-raceway system may provide a route, but it remains visible. The installer checks that the conductors, fittings, and installation are allowed by the product listing and applicable code.
The practical lesson is that “hidden” can mean concealed inside the wall or neatly contained on its surface. Only the first is behind drywall, and it uses a different wiring method.
Frequently Asked Questions
These answers address the most common choices and code concerns when routing electrical wiring near drywall. Requirements can vary with the locally adopted code edition and amendments, so confirm local rules before work begins.
Can I put a surface raceway behind drywall?
No. Surface raceway is intended to remain surface-mounted. Burying it can conflict with its listing and make its cover or conductors inaccessible.
Can I run NM-B inside a wall?
NM-B may be installed in suitable wall cavities where permitted by the adopted code. It still needs proper support, protection, boxes, and connections.
Can I put NM-B inside a surface raceway?
Do not assume so. Use only conductors or cables that the raceway listing and applicable code allow. NM-B is not a general-purpose raceway conductor set.
How far from a stud edge must a cable hole be?
NEC 300.4(A)(1) generally calls for at least 1¼ inches (32 mm) from the nearest framing-member edge to the hole. If that cannot be maintained, prescribed steel protection is required.
How often must NM-B be secured?
NEC 334.30 generally requires support at intervals no greater than 4½ feet (1.4 m) and within 12 inches (300 mm) of boxes, cabinets, or fittings, subject to stated exceptions.
Can I cover a junction box with drywall?
No. NEC 314.29 requires boxes to remain accessible without removing building finish or structure. Keep the cover reachable.
Does NM-B in a wall need ventilation?
There is no general CFM or ventilation requirement for ordinary NM-B concealed in a wall cavity. Do not use the cavity or raceway as a ventilation duct.
Can I use a raceway to avoid opening the wall?
Often, a listed surface-raceway system can provide an exposed route, if it is suitable for the conductors and use. It will remain visible and must be installed with compatible parts.
Should I do this work myself?
That depends on your skills and local rules. If you cannot confirm the circuit is off, identify the route, or make code-compliant connections, use a qualified electrician.
Do I need a permit or inspection?
Possibly. Permit and inspection requirements depend on local rules and the type of work. Check with the local building department before starting.
Choose one clear method, follow its rules, and keep every box accessible. For a fully concealed finish, route permitted NM-B within the wall cavity. For an exposed route, use a listed raceway and leave it on the surface. Confirm the adopted code, permit needs, and inspection timing before closing the wall.
(This article was written by one of our staff writers, Michael Holloway. Visit our Meet the Team page.)
