What Is Concealed AV Wiring? (In-Wall Tube)
Concealed AV wiring is a low-voltage cable route hidden inside a wall, often using a smooth tube called a raceway. It lets you replace or add HDMI, fiber, speaker, and control cables later without opening the wall. Plan for cable size, bends, access, code-listed materials, separation from power wiring, and proper firestopping.
One important planning figure is 360 degrees: under NEC Article 362.26, the total bends in a run of electrical nonmetallic tubing (ENT) between pull points must not exceed that amount. Check the edition adopted in your area, since local rules and amendments can differ. This limit matters because tight or numerous bends can make a cable hard to pull or damage it.
Plan the Route, Cable Types, and Raceway
A concealed AV raceway is a protected path for low-voltage cable, not a power conduit or air duct. Before choosing a tube, identify the devices at each end, the cable and connector sizes, the wall construction, and any rated assemblies. Those details determine the route, access points, and materials you need.
Start by mapping a path from the source equipment to the display, speaker, or control point. Look for framing, plumbing, HVAC, existing electrical wiring, and heat sources. If you cannot see inside a closed wall, use suitable inspection tools or make a small exploratory opening before cutting a larger one. Check for permits and inspection requirements with your local building department.
Choose a raceway that accommodates the largest connector, not just the cable jacket. Some HDMI connectors are much wider than their cable, and pre-terminated fiber cables may have delicate ends. A route that accepts bare cable may still be too tight for a connector. Do not assume every cable can be re-terminated in place.
| Planning item | What to check | Why it matters |
|---|---|---|
| Raceway size | Largest connector and planned future cables | A cable may fit while its connector will not |
| Cable type | HDMI, fiber, speaker, control, or network cable | Different cables have different pull and bend limits |
| Wall route | Framing, utilities, heat, and access | Avoids conflicts and unsafe cuts |
| Raceway material | ENT or another code-appropriate pathway | Rules depend on material and location |
| Building assembly | Rated wall, floor, or plenum space | May require listed cable or a listed firestop system |
ENT is flexible, nonmetallic tubing that can serve as a raceway where permitted by code. A tube does not make every cable suitable for every location. Use cable listed for its application; CL2 or CL3 may apply to some Class 2 AV runs, while riser or plenum ratings may be required in certain spaces. Follow the cable maker’s instructions and local code.
Check Access, Bends, and Separation
A pull point is an accessible place where cable can enter, leave, or be pulled through the raceway. It may be an outlet opening or an accessible box, depending on the design. Plan pull points so that future work is possible without cutting the wall, while keeping the path within the code’s bend limit and the cable maker’s limits.
For ENT, NEC 362.26 sets a maximum of 360 degrees of bends between pull points. Keep the bends broad and smooth, even when the code limit allows more. Cable bend radius varies by product; there is no single value that applies to all HDMI, fiber, speaker, and control cables. Check the cable manufacturer’s stated minimum radius and pulling limits.
ENT support also has a defined threshold: NEC 362.30 generally requires support within 3 feet of each box or fitting and at intervals no greater than 3 feet. Confirm the adopted code and any local amendments. Protect tubing from screws, nails, sharp edges, and crushing. Use suitable fittings or bushings at openings so cable jackets do not rub on rough edges.
Keep AV/Class 2 cable out of the same raceway as branch-circuit conductors unless a specific code-permitted separation or barrier arrangement applies. NEC 725.136 addresses separation. There is no one universal spacing rule for every installation, so check the applicable code rather than relying on a guessed distance. An AV tube is not a ventilation duct; keep it separate from HVAC ducts and maintain required fire, smoke, and plenum boundaries.
Install and Finish the In-Wall Tube
Install the raceway while the wall is open whenever possible. Secure it to the framing, protect it from fasteners, and keep the route accessible at both ends. Before closing the wall, inspect the full path for sharp turns, loose supports, crushed sections, and conflicts with other building systems.
A practical sequence is:
- Mark the source and destination openings, then confirm the route from both sides of the framing.
- Cut openings only after checking for hidden wiring, plumbing, and structural limits on drilling or notching.
- Fit and secure the tubing and its connectors. Keep the supported spacing within the applicable code limits.
- Add accessible pull points where needed and leave enough room for the cable and connector to pass.
- Install a pull string if appropriate, and cap or cover open ends during construction to keep debris out.
- Check the pathway with a test pull or suitable flexible leader before closing the wall.
Use openings and low-voltage mounting hardware suited to the wall assembly and device. Do not bury a splice or pull point that needs to remain accessible. Keep the AV raceway separate from power wiring; a shared wall cavity does not mean the cables can share a tube.
If the tube passes through a fire-rated wall or floor, treat the opening as a firestop issue. The tube alone does not preserve the assembly’s rating. Use a firestop system listed for the exact assembly and the raceway configuration, and follow its installation details. Ask the inspector or a qualified firestop professional if the assembly or required system is unclear.
Test, Label, and Verify Compliance
Before the wall is closed, check that the route is clear and that the ends are accessible. After pulling cable, test it using a method suited to the cable and equipment. Label both ends and record the route, raceway type, and any hidden pull points so future work does not depend on guesswork.
Pull cable with steady force and avoid twisting or yanking it around bends. Follow the cable manufacturer’s minimum bend radius and maximum pulling tension; these values differ by product. If the cable snags, stop and find the cause rather than pulling harder. A damaged cable may still appear intact but fail during use.
Use a cable tester or appropriate device check. For HDMI, test the actual signal path with the intended source and display when possible. For fiber, use the method recommended for that cable and system. Confirm speaker or control runs with suitable continuity or functional tests. Replace a cable that fails rather than hiding a questionable run behind finished surfaces.
Before closing the wall, verify:
- Raceway support, fittings, and bend total meet the locally adopted code.
- Cable ratings match the location and application.
- AV and power wiring are not improperly combined in the raceway.
- Rated penetrations have the correct listed firestop system.
- Cable ends are labeled and the route is documented.
- The pull path works without exceeding cable limits.
Installation Examples and Common Choices
These examples are typical planning scenarios, not claims about a specific home. I use them to show how the same basic raceway rules lead to different layouts. In each case, confirm the wall details and local requirements before cutting or installing materials.
| Scenario | Practical route choice | Main check before closing |
|---|---|---|
| New framed wall behind a display | ENT from an accessible source location to a low-voltage opening behind the display | Keep the AV path separate from branch-circuit wiring; confirm connector clearance |
| Finished wall with limited access | A carefully surveyed route with accessible openings at both ends | Check for hidden services and framing limits before drilling |
| Fiber or pre-terminated HDMI run | Larger, smoother raceway with few bends and adequate pull access | Confirm connector dimensions, cable bend radius, and pulling limits |
| Route through a rated floor or wall | Raceway and penetration details matched to the rated assembly | Use a listed firestop system for that assembly and configuration |
For a new wall, I plan the tube before the electrician closes in the power route. That makes it easier to keep systems apart and to add support where needed. For a retrofit, the hardest part is often not fitting the tube; it is proving the path is clear and finding a route that remains pullable. A small inspection opening can prevent a much larger repair later.
FAQ: Concealed AV Wiring and In-Wall Tubes
These answers cover the most common questions about using an in-wall tube for AV cables. Local code, the cable listing, and the manufacturer’s instructions still control the final installation. When a wall is rated or the route is uncertain, confirm the required method with the local authority or a qualified installer.
Is concealed AV wiring the same as electrical conduit?
No. It is a raceway for low-voltage AV cable. Do not use it as a shortcut for branch-circuit wiring.
Can HDMI and power wires share one tube?
Do not place AV/Class 2 cable and branch-circuit conductors together unless a specific code-permitted arrangement applies. Check NEC 725.136 and the locally adopted code.
How many bends can ENT have between pull points?
The NEC limit in Article 362.26 is 360 degrees between pull points. Verify the edition and local amendments that apply.
How often must ENT be supported?
NEC 362.30 generally calls for support within 3 feet of each box or fitting and at intervals no greater than 3 feet. Check local requirements.
What size tube should I use?
Choose a raceway that fits the largest connector and planned future cables, with room to pull them without exceeding their limits. There is no single size suited to every AV run.
Can I run any cable inside the tube?
No. The cable must be listed for its location and use. Some runs require CL2 or CL3 cable, or a riser or plenum rating, depending on the route.
Does a raceway set the cable’s bend radius?
No. Follow the cable manufacturer’s minimum bend radius. Requirements differ among HDMI, fiber, speaker, and control cable.
Does the tube need to be sealed for airflow?
An AV raceway is not an air duct, so there is no CFM target. Keep it separate from HVAC and preserve required fire, smoke, and plenum boundaries.
What if the tube passes through a fire-rated wall or floor?
Use a listed firestop system that matches the assembly and the raceway configuration. Do not assume the tube itself preserves the rating.
Should I leave a pull string inside?
A pull string can help with future cable changes if it is suitable for the route and does not block the cable. Leave both ends accessible and label them.
A well-planned in-wall AV tube is accessible, supported, and sized for real connectors and future pulls. Check the adopted code, cable instructions, and firestop details before closing the wall; then test, label, and document the completed route.
(This article was written by one of our staff writers, Garrett Vance. Visit our Meet the Team page.)
