In this guide
The best way to run cables behind a wall is to install low-voltage electrical boxes at entry and exit points, then use a fish tape to guide the cables through the wall cavity.
- You install low-voltage boxes at both holes
- You locate studs first and maintain 2.5-inch clearance
- You use fish tape to pull cables through
- Holes are correctly aligned in the same wall cavity
- You run raw power cables inside the wall
- Fire blocks obstruct the cavity and aren’t accounted for
- Holes are misaligned between boxes
- There’s insufficient clearance from studs
What You Need Before You Start
Gather these tools before cutting anything:
- Stud finder
- Low-voltage electrical boxes (two)
- Fish tape or fish sticks
- Drywall saw or oscillating tool
- Electrical tape
- Pencil and level
Step-by-Step: How to Run Cables Behind a Wall
1. Find your studs. Use a stud finder to map the studs in the area. You need to route cables in the cavity between two studs, keeping at least 2.5 inches of clearance from each stud edge.
2. Mark and cut your holes. Place the first box behind or near your TV mount location. Place the second box low on the wall, hidden behind furniture or in an adjacent room. Trace the box outline and cut 1/8 to 3/16 inches inside the line so the box lip grips the drywall securely.
3. Install the low-voltage boxes. Screw both boxes into the drywall before threading any cables. These boxes are specifically designed for safe passage of low-voltage wiring like HDMI, ethernet, and speaker cables. If you’re connecting a display, check out our guide on whether USB-C can connect to HDMI to choose the right cable before routing it.
4. Attach cables to the fish tape. Feed the fish tape down from the top hole. Once it emerges at the bottom, tape your cables securely to the hook end using electrical tape. Keep the taped section smooth so it doesn’t snag on drywall edges.
5. Pull the cables through. Slowly retract the fish tape from the top while a second person feeds slack from below. If resistance is heavy, you may have hit a fire block — a horizontal wooden spacer inside the wall cavity. You’ll need to drill through it or reroute.
Common Setups at a Glance
| Setup | Works? | Need | Note |
|---|---|---|---|
| HDMI or ethernet behind TV | Yes | Low-voltage boxes + fish tape | Most common use case |
| Standard power cable in wall | No | Licensed electrician | Fire hazard without conduit |
| Cables crossing fire block | Sometimes | Drill bit + flex bit | Adds time and complexity |
| Adjacent room exit point | Yes | Aligned holes in same cavity | Keeps cables fully hidden |
What to Avoid
Never run a standard extension cord or raw power cable inside a wall cavity — this is a fire hazard and violates building codes in most regions. Only low-voltage signal cables belong in an unprotected wall cavity. For more on display cable compatibility, see our article on why USB-C to HDMI sometimes fails before you seal everything up.
Bottom line: The best way to run cables behind a wall is to use low-voltage electrical boxes, a fish tape, and a stud finder. Plan your hole locations carefully, avoid fire blocks where possible, and never run power cables in an open wall cavity. Done right, this gives you a clean, permanent cable management solution.