Hide Cables Behind Plasterboard (Drywall Grommets)
A drywall grommet protects cable from the sharp edge of a wall opening; it does not make every cable safe to hide. First identify the cable and its in-wall rating, check the wall and route, and use a grommet sized for the drywall and cutout. Keep splices accessible, protect framing holes, and follow local code.
A wall-mounted TV can look like a scene from a sleek sci-fi film until a bundle of cords drops into view. A grommet can create a neat passage through plasterboard, also called drywall, but choosing the right opening is only one part of the job. The cable, route, wall type, and local rules all matter.
I often find that the real problem is not the grommet. It is an ordinary equipment cord that someone plans to conceal behind the wall. A tidy opening cannot change that cord’s rating or make it suitable for concealed installation.
Plan the cable route and identify cable ratings
A cable’s jacket, markings, and product documentation help establish what it is designed to do. Before cutting drywall, trace each cable from its source to its destination, note any connection or splice, and check whether the route passes through a fire-rated wall or an environmental-air space. Local code and the product instructions control the final choice.
Make a list of every cable, such as coaxial, speaker, network, HDMI, or power. Then identify where each one starts and ends. If you cannot identify a cable or verify its rating, pause and have a qualified installer check it.
An in-wall rating means the cable is made and listed for use inside a building wall. A flexible equipment cord may look similar to in-wall cable, but that does not give it the same permission. Under the 2023 National Electrical Code (NEC), flexible cords and cables must not be run through holes in walls or concealed behind building finishes (NEC 400.12). Do not hide extension cords, power strips, or ordinary TV and device cords behind drywall.
For HDMI, USB, speaker, or data runs, use cable specifically marked or documented for the intended in-wall location. If you need to move a power outlet, use an approved wiring method or a listed power-relocation system. A grommet alone does not make line-voltage wiring safe or code-compliant.
Check stud, box, and fire-rated-wall clearances
A safe route must protect cables from screws and nails, avoid damage to existing services, and preserve required access. Check the wall before drilling, and do not assume that an open-looking cavity is clear. Where a wall is fire-rated, the opening and any penetrations may need a compatible listed firestop system.
Use a stud finder and inspect both sides of the wall when possible. Look for outlets, switches, plumbing fixtures, heating equipment, and signs of framing or wiring. A stud finder can help locate objects, but it cannot confirm that a proposed route is clear. If the route is uncertain, inspect the cavity through an existing opening or ask a professional to assess it.
When a cable passes through a bored hole in a wood framing member, the hole’s edge must be at least 1¼ inches (32 mm) from the nearest edge of the framing. If it cannot meet that setback, protect the cable with a steel plate at least 1⁄16 inch (1.6 mm) thick, sized to cover the risk area (2023 NEC 300.4(A)(1)). This plate is often called a nail plate. It helps stop a later screw or nail from reaching the cable.
A junction box is an enclosure for wire connections. Any junction or outlet box must remain accessible without removing building finish or structure (NEC 314.29). Do not bury a splice behind drywall or use a grommeted opening as a substitute for a covered, accessible box. At an outlet or junction box, leave at least 6 inches (150 mm) of free conductor measured from where it enters the box. If the box opening is less than 8 inches (200 mm) in any dimension, at least 3 inches (75 mm) must extend outside the opening (NEC 300.14).
Choose a drywall grommet that fits
A drywall grommet is a trim piece that lines or finishes a cut edge. It helps keep a cable from rubbing against rough drywall, but it is not a box, firestop, or protective plate for framing. Match the grommet to the wall thickness, cutout size, cable bundle, and the manufacturer’s instructions.
There is no universal grommet-hole size. Products vary, so use the specified cutout dimensions rather than copying a measurement from another installation. Check that the grommet is made for the drywall thickness and that its cable capacity suits the number and size of cables. Do not force a bundle through a small opening.
| Situation | Suitable approach | Do not do this |
|---|---|---|
| In-wall-rated signal cable through drywall | Use a grommet specified for the cutout and wall thickness | Leave the cable against a raw, sharp edge |
| Ordinary HDMI, USB, or device cord | Replace it with a cable rated for in-wall use, or use a surface route | Hide the cord behind drywall because it passes through a grommet |
| Power outlet needs to move | Use an approved wiring method or listed power-relocation assembly | Bury an extension cord or power strip |
| Cable crosses a framing member | Meet the 1¼-inch setback or install the required protective steel plate | Assume the grommet protects the cable from framing screws |
| Wall is fire-rated | Use a compatible listed firestop system where required | Treat a trim grommet as firestop |
If the wall is part of an environmental-air space, confirm that the cable is suitable for that location. If you cannot tell whether a wall is fire-rated or part of such a space, do not cut until you have checked the building plans, product details, or local requirements.
Install the grommet and route the cable
A controlled installation starts with a confirmed route and correctly sized opening. De-energize any applicable circuit before working near electrical wiring. Cut only after checking for hidden services, and follow the grommet maker’s directions for the cutout, fit, and cable capacity.
- Mark the opening only after confirming the route and checking for studs, pipes, existing wires, and bracing. Keep the opening clear of framing edges and do not cut a stud or other structural member to make a cable path.
- Cut the drywall to the manufacturer’s specified size. A hole that is too large may not hold the grommet securely; one that is too small can pinch the cable or damage its jacket.
- Fit the grommet as directed, then feed the cable without scraping, crushing, or sharply bending it. Keep the cable within its stated bend limits and avoid pulling hard on connectors.
- If the cable passes through framing, confirm the required setback or install suitable nail plates. Keep concealed splices in accessible, covered boxes.
- Secure the grommet and check that it sits as intended. Restore any required firestop with a listed system compatible with the wall and penetration.
Do not use the grommet opening to conceal a cable connection or leave a loose splice inside the wall. If you find an existing splice that would become inaccessible, stop and plan a route that keeps the box accessible.
Verify protection, access, and finished appearance
A finished opening should hold the grommet firmly and leave the cable free from sharp edges, pinching, or strain. Before closing the job, check the cable path, all boxes, any required firestop, and the signal or circuit. A neat appearance is not enough if the cable is damaged or a connection is hidden.
Inspect both ends of the cable and the visible route. Check that no insulation is scraped, no cable is compressed, and no connector is bearing the cable’s weight. Confirm that every junction box remains accessible and that required protective plates and firestop are in place.
Then test the affected function. For a signal cable, check the connected equipment at both ends. For work involving an electrical circuit, use a suitable test and have a licensed electrician handle work that is outside your skill or local legal scope. If a cable fails, do not assume the grommet is the cause; check the route, connectors, and cable rating.
Typical installation scenarios
These examples show how the same opening can lead to different decisions. They are practical scenarios, not code approvals; the exact requirements depend on the cable, wall, product instructions, and locally adopted rules.
In one common TV-wall setup, a homeowner wants to pass HDMI and network cables through two grommets. The right first step is to verify that each cable is specifically rated for in-wall use. If an ordinary equipment cord is in the bundle, replace it with an appropriate in-wall cable rather than pushing the whole bundle through a finished opening.
In another setup, a cable route crosses a wood stud. The installer checks the hole position against the 1¼-inch setback. If the hole is too close to the edge, the cable needs the specified protective steel plate. A grommet at the drywall face does not solve that framing hazard.
A third setup involves a power connection behind a wall-mounted display. The installer does not hide a power cord through a grommet. Instead, the power route uses an approved wiring method or a listed power-relocation assembly, and any boxes remain accessible. These checks may take more planning, but they prevent an attractive finish from hiding a safety problem.
Common questions about drywall grommets
A grommet can make a cable opening cleaner and help protect the cable at the drywall edge. It cannot change a cable’s rating, protect it from screws inside framing, replace an electrical box, or restore a fire barrier. Use the answers below to check the common points before cutting.
Can I run a TV power cord through a drywall grommet?
No. A grommet does not make an ordinary power cord suitable for concealed installation. Use an approved wiring method or a listed power-relocation system.
Can HDMI or USB cables go behind drywall?
Only use cables specifically rated for in-wall use and the conditions along the route. A flexible device cord is not made suitable by passing it through a grommet.
Does a grommet replace an electrical box?
No. A grommet protects or finishes the opening edge. Connections and splices must be inside an appropriate box that remains accessible.
Is there a standard hole size for a drywall grommet?
No. Use the cutout size listed by the grommet’s manufacturer. It must suit the drywall thickness and the number and size of cables.
How far must a bored framing hole be from the edge?
Under the 2023 NEC baseline, keep the hole edge at least 1¼ inches (32 mm) from the framing edge. Otherwise, install a protective steel plate at least 1⁄16 inch (1.6 mm) thick, sized to protect the wiring.
Can I cover a junction box with drywall?
No. A junction or outlet box must remain accessible without removing building finish or structure. Keep it accessible and covered with an appropriate cover.
Do I need firestop around the opening?
If the wall or floor assembly has a required fire-resistance rating, preserve it with a compatible listed firestop system where required. A trim grommet is not firestop.
Can I use this method in a rental?
Ask the property owner before cutting or changing the wall. If you cannot get permission, use a removable surface cable cover, and still avoid unsafe or unsuitable power cords.
When should I hire an electrician or installer?
Get qualified help if you cannot identify a cable, confirm a safe route, preserve a fire-rated wall, or move line-voltage power. Local rules may also limit who can perform electrical work.
Make the opening tidy without hiding a hazard
A clean cable opening begins with the right cable, not the grommet. Check ratings, inspect the route, protect framing holes, and keep boxes accessible. Then fit a grommet made for the wall and cutout, and restore any required firestop. If any part of the route or cable is uncertain, pause and verify it before closing the wall.
(This article was written by one of our staff writers, Michael Holloway. Visit our Meet the Team page.)
