Quick Answer
Planning Your Route
Good planning is the difference between a two-hour project and a two-day headache. Before you pick up a drill, figure out exactly how the cable will get from point A to point B.
Identify your access points
Every in-wall cable run needs a way to enter the wall cavity from above or below. The two most common access points are:
- Attic access: The easiest option. You drill down through the top plate of the wall from the attic and drop the cable into the wall cavity. Works well for second-floor rooms and any room directly below an accessible attic.
- Basement or crawl space access: Drill up through the bottom plate from below. This is the go-to method for first-floor rooms with an unfinished basement or crawl space underneath.
If you have neither attic nor basement access to the wall you want to wire, the job becomes significantly harder. You may need to open additional drywall, use surface-mount raceway, or hire a professional.
Locate studs and obstacles
Use a stud finder to map the stud locations in the wall where you want the outlet. You need to place your outlet between two studs since the cable will drop (or rise) through the open cavity between them. While you're scanning, check for:
- Electrical wiring: Some stud finders detect live wires. If you see an outlet or switch on the same wall, the electrical wiring may run through the cavity you're targeting.
- Plumbing: Bathrooms and kitchens often have plumbing running through interior walls. Avoid these cavities entirely.
- HVAC ducts: Metal ductwork blocks your cable path completely. Check the attic or basement to see if any ducts pass through the wall you want to use.
- Fire blocks: Some walls have horizontal blocking (solid wood) between the top and bottom plates, installed as fire stops. These block your cable path and require an additional drill hole to pass through.
Plan entry and exit points
Decide exactly where the wall plate will go and where the cable will emerge in the attic, basement, or network closet. Mark both locations. At the wall plate end, choose a spot at the same height as your existing electrical outlets (typically 12 to 16 inches from the floor) for a clean, consistent look. At the other end, plan where the cable will terminate: at a patch panel, switch, or router.
Tools and Materials Checklist
Gather everything before you start. Having the right tools on hand prevents mid-project trips to the hardware store and makes fishing cable dramatically easier.
| Tool / Material | What It Does | Essential? |
|---|---|---|
| Stud finder | Locates studs, wiring, and pipes behind drywall | Yes |
| Drill with flexible installer bit | Drills through the top or bottom plate from the attic or basement. A flex bit bends to reach tight angles | Yes |
| Fish tape or glow rods | Feeds through the wall cavity to pull cable. Glow rods are rigid fiberglass rods that glow under UV light for easy retrieval in dark cavities | Yes |
| Drywall saw | Cuts the low-voltage box hole in the wall | Yes |
| Low-voltage old-work bracket | Mounts in the drywall to hold the wall plate. Unlike electrical boxes, low-voltage brackets have an open back so cable passes through freely | Yes |
| Keystone jack (Cat5e or Cat6) | The female Ethernet port that mounts in the wall plate. Wires punch down on the back | Yes |
| Keystone wall plate | The face plate that screws onto the low-voltage bracket and holds the keystone jack | Yes |
| Solid-conductor Ethernet cable (CM/CMR rated) | In-wall rated cable designed for permanent runs. Cat6 is recommended for most homes | Yes |
| Cable tester | Verifies all eight pins are wired correctly after termination | Yes |
| Punch-down tool | Seats wires into the keystone jack IDC contacts and trims the excess | Yes |
| Pull string / pull line | Thin string used to pull cable through long or difficult runs. Tie to the cable and pull from the other end | Helpful |
| Cable staples or J-hooks | Secures cable along joists in the attic or basement. Prevents sagging and keeps runs neat | Helpful |
| Fire-rated caulk | Seals holes drilled through plates between floors. Required by building code | Yes (multi-floor runs) |
| Headlamp | Keeps your hands free while working in dark attics, basements, and wall cavities | Helpful |
Step-by-Step: Running Cable Through the Wall
This guide covers the most common scenario: running cable from an attic or basement down (or up) into a wall cavity and terminating at a keystone jack wall plate. The same principles apply whether you're going from attic to second floor, basement to first floor, or any other configuration with plate access.
Plan the route and identify obstacles
Use your stud finder to confirm the exact cavity you will use. Mark the stud locations on both sides of your target cavity. Go into the attic or basement and identify the top plate or bottom plate of that same wall. Line up your marks with a reference point that is visible from both sides, such as an existing outlet, a vent, or an exterior wall corner.
Look for any obstructions in the cavity: cross bracing, plumbing pipes, or existing wiring. If the cavity is blocked, move to the next one over.
Cut the low-voltage box hole at the destination
Hold the low-voltage old-work bracket against the wall at the desired height (matching your existing outlets for a clean look) and trace around it with a pencil. Use a drywall saw to cut along the traced line. Cut carefully and keep the edges clean so the bracket sits flush.
Before cutting, use a stud finder one more time right at the marked location to confirm you're between studs and there are no wires or pipes directly behind the cut. Once the hole is open, look inside with a flashlight to verify the cavity is clear.
Drill through the top or bottom plate
From the attic (for top plate) or basement (for bottom plate), locate the correct wall cavity. Measure from the same reference point you used downstairs to make sure you're drilling into the right cavity. The top plate is the horizontal 2x4 (or 2x6) at the top of the wall. The bottom plate sits on the subfloor.
Drill a 3/4-inch hole through the center of the plate using a flexible installer bit, spade bit, or auger bit. Drilling at the center of the plate ensures you don't weaken it structurally and gives you the most room to feed cable without snagging on the edge of the hole.
Fish the cable through the wall cavity
This is the step that determines whether the job takes ten minutes or an hour. You have a few options depending on your situation:
- Drop method (attic access): Feed fish tape or glow rods down through the hole in the top plate. Gravity helps. Retrieve the end at the outlet hole. This is the easiest approach.
- Push-up method (basement access): Push fish tape or glow rods up through the hole in the bottom plate. You may need a helper at the outlet hole to grab the end as it passes by.
- Pull string method: Tie a small weight (like a hex nut on a string) and drop it from the attic through the drilled hole. Retrieve the string at the outlet hole. Tie the Ethernet cable to the string and pull it up through the cavity. This method works well for long or tricky runs.
If the fish tape gets stuck, it usually means there's a fire block or cross brace in the cavity. You'll need to cut a small access hole in the drywall at that point, drill through the obstruction, and patch the drywall afterward.
Pull the cable through to both ends
Once the fish tape is through, attach the Ethernet cable to the end with electrical tape (wrap it tightly and taper the connection so it won't snag). Pull the cable through slowly and steadily. Have a helper feed cable from the other end to prevent kinks.
Leave 12 to 18 inches of slack at the wall plate end for termination and future re-termination if needed. Leave a generous service loop (several feet) at the attic or basement end, especially if the cable will terminate at a patch panel. You can always trim excess cable, but you can never add length.
Install the low-voltage bracket and wall plate
Insert the low-voltage old-work bracket into the hole you cut in step 2. Tighten the screws to clamp the bracket wings against the back of the drywall. The bracket should sit flush with the wall surface.
Thread the cable through the bracket opening. The bracket holds the wall plate and gives the installation a finished, professional look. Without a bracket, you'd have a bare hole in the drywall with cable sticking out.
Terminate with a keystone jack
Strip about 2 inches of the outer jacket from the cable end. Separate the twisted pairs and lay each wire into the color-coded slot on the keystone jack following the T568B wiring standard (the jack will have color labels printed on it). Use a punch-down tool to seat each wire into the IDC (insulation displacement contact) and trim the excess in one motion.
Snap the completed keystone jack into the wall plate, then screw the wall plate onto the low-voltage bracket. The result is a clean, permanent Ethernet port on your wall that looks like it was installed during construction.
At the other end of the cable (in the attic, basement, or network closet), terminate with either another keystone jack on a patch panel or an RJ45 connector for a direct connection to your switch or router.
Test the run
Plug a cable tester into both ends of the cable and run a wiremap test. The tester checks all eight conductors for continuity, correct pin-to-pin mapping, and common faults like opens, shorts, reversed pairs, and split pairs.
A passing test means your cable is ready for use. If any pin fails, re-terminate the failed end. The most common cause of failed keystone terminations is a wire that wasn't fully seated in the IDC slot during punch-down.
Routing Strategies for Different Situations
Not every cable run is a straight vertical drop from the attic. Here are the most common routing scenarios and how to handle each one.
Vertical runs (same floor, attic or basement access)
The simplest scenario. Drill through the top or bottom plate directly above or below the outlet location, then drop or push the cable straight down or up through the cavity. This is a single-cavity run with no horizontal travel. Most rooms with direct attic or basement access fall into this category.
Horizontal runs (between rooms on the same floor)
If you need to go horizontally through multiple stud cavities on the same floor, you'll need to drill through each stud or route through the attic or basement. Going through the attic is almost always easier: run cable horizontally across the attic joists and drop down into each room's wall cavity separately. Drilling through studs inside the wall is possible but requires opening drywall at each stud location.
Floor-to-floor runs
Running cable between the first and second floor requires drilling through the top plate of the first-floor wall, crossing the floor cavity (the space between floors), and drilling through the bottom plate of the second-floor wall. If both walls are directly stacked, the cable passes through the same continuous cavity. If they're offset, route through the floor cavity horizontally to reach the second-floor wall.
Working with Different Wall Types
Standard drywall over wood studs is the easiest wall type to work with. Other wall constructions present additional challenges.
Standard drywall (gypsum board over wood studs)
This is the ideal scenario. Drywall cuts easily with a drywall saw, studs are predictable at 16-inch centers, and wall cavities are open between the top and bottom plates. The steps in this guide are written primarily for this wall type.
Plaster over lath
Older homes often have plaster walls, which are harder to cut through than drywall. Use an oscillating multi-tool with a plaster-cutting blade instead of a drywall saw. Cut slowly to prevent cracking the surrounding plaster. The stud spacing in plaster homes may be irregular, so measure carefully with a stud finder.
Exterior walls (insulated cavities)
Exterior walls are filled with insulation (fiberglass batts, blown cellulose, or spray foam). Insulation makes fishing cable much harder because it grabs the fish tape and creates friction. For exterior walls, pull the insulation aside at the outlet hole if possible, and use glow rods rather than flat fish tape. Glow rods are rigid enough to push through fiberglass insulation. Spray foam cavities are essentially impassable and usually require an alternative route.
Brick, stone, or concrete walls
Solid masonry walls cannot be fished. The only options are surface-mount raceway (cable channel on the outside of the wall), furring out the wall with wood strips to create a cavity, or using a masonry drill to bore through the wall for an exterior route. This is typically a job for a professional.
Fire Stopping Requirements
Any hole you drill through a top plate or bottom plate that connects two separate floor levels must be sealed with fire-rated material. This is not optional. It is a building code requirement in virtually every jurisdiction, and it exists to prevent fire and smoke from traveling rapidly between floors through open wall cavities.
Intumescent caulk is the easiest option. Apply it around the cable where it passes through the plate hole. The caulk expands when exposed to heat, sealing the opening during a fire. Firestop putty pads are another option and are reusable if you ever need to pull additional cables through the same hole.
For runs that stay on a single floor (for example, from an attic down into a second-floor wall without crossing into the first-floor ceiling), fire stopping is generally not required because you're staying within the same fire compartment. But when in doubt, seal it anyway.
Cable Separation from Electrical Wiring
Ethernet cable is susceptible to electromagnetic interference (EMI) from power lines. Running data cable too close to electrical wiring can cause packet errors, reduced speeds, and intermittent connectivity problems. Follow these separation rules:
- Parallel runs: Maintain at least 12 inches of separation between Ethernet cable and electrical wiring when they run in the same direction along the same path.
- Crossings: When data and power cables must cross, cross them at a 90-degree angle. A perpendicular crossing minimizes the length of cable exposed to the electromagnetic field.
- High-power circuits: Keep even more distance (24 inches or more) from high-amperage circuits like those serving HVAC equipment, electric dryers, or electric ranges.
- Shared cavities: Avoid running Ethernet cable in the same wall cavity as electrical wiring whenever possible. If you must share a cavity, keep the data cable pressed against one stud and the electrical wiring against the opposite stud.
Shielded Ethernet cable (STP) provides better EMI rejection than unshielded cable (UTP), but proper separation is still the first and best defense regardless of cable type.
Common Mistakes to Avoid
These are the problems that catch first-time cable pullers most often. Avoid them and your run will go smoothly.
Drilling into plumbing or electrical
Always verify the cavity is clear before drilling. Use a stud finder with wire and pipe detection, look inside the wall cavity through the outlet hole with a flashlight, and check both sides of the wall for outlets, switches, and plumbing fixtures that indicate hidden infrastructure.
Not using a low-voltage bracket
Stuffing cable through a bare hole in the drywall looks unprofessional and provides no protection for the cable or the termination. Low-voltage brackets cost a few dollars and give you a proper mount for a wall plate. They also meet code requirements.
Sharp bends and kinks in the cable
Ethernet cable has a minimum bend radius, typically four times the cable diameter. Sharp bends damage the internal twist geometry that controls crosstalk, which degrades performance. Route cable in gentle curves, especially at corners and where it enters the wall plate. Never staple cable in a way that creates a sharp bend.
No slack at termination points
Leave 12 to 18 inches of slack at the wall plate and a generous service loop at the patch panel end. Without slack, you can't re-terminate if a keystone jack fails, and any settling or movement in the house can put tension on the termination.
Using stranded cable for in-wall runs
Stranded cable is designed for short patch cables between a wall plate and a device. Solid-conductor cable is designed for permanent in-wall runs because it maintains signal quality over long distances and terminates properly in keystone jacks and patch panels. Don't use stranded cable inside walls.
Forgetting fire stopping
Every hole you drill between floors must be sealed. It's easy to forget this step in the excitement of a successful cable pull, but it's a building code requirement and a critical fire safety measure. Keep fire-rated caulk in your tool bag and seal penetrations immediately.
When to Hire a Professional
Most single-room cable runs are well within DIY ability. But some situations are better left to a licensed low-voltage installer or electrician:
- Brick, stone, or concrete walls: Solid masonry requires specialized drilling equipment and techniques that go beyond standard DIY tools.
- Multiple floors with no attic or basement access: Without access above or below, running cable requires opening significant sections of drywall and patching afterward.
- Whole-house wiring (more than 3-4 runs): If you're wiring an entire house, a professional can do it faster, pull multiple cables simultaneously, and set up a proper structured wiring panel. See our home network wiring guide for planning a multi-room installation.
- Commercial buildings: Commercial installations have additional code requirements including plenum-rated cable for air handling spaces, conduit requirements, and specific fire stopping standards.
- You're not comfortable working in the attic or crawl space: Safety comes first. Attics have exposed insulation, limited headroom, and the risk of stepping through the ceiling. If you're not comfortable working in these spaces, the cost of a professional is money well spent.
Frequently Asked Questions
Can I run Ethernet cable through walls myself?
Yes. Running Ethernet cable through walls is a common DIY project. Unlike electrical wiring, low-voltage data cable does not require a permit in most jurisdictions. You need basic tools including a drill, fish tape, stud finder, and a drywall saw. The project is straightforward if you have attic or basement access above or below the wall where you want the outlet.
Do I need to use conduit for Ethernet cable in walls?
Conduit is not required for Ethernet cable inside residential walls in most areas. Low-voltage cable like Cat5e and Cat6 can be run directly through wall cavities without conduit. However, conduit makes future cable upgrades easier and is required in some commercial installations. Check your local building codes for specific requirements.
How far should Ethernet cable be from electrical wiring?
Keep Ethernet cable at least 12 inches away from electrical wiring when running parallel. If the cables must cross, cross them at a 90-degree angle to minimize electromagnetic interference. This separation is especially important for unshielded cable like standard Cat5e and Cat6. Shielded cable is more tolerant but maintaining separation is still best practice.
What type of Ethernet cable should I use for in-wall runs?
Use solid-conductor Ethernet cable rated for in-wall installation (look for CM or CMR rating on the jacket). Solid cable is designed for permanent runs because it maintains signal quality over longer distances. Cat6 is the best choice for most homes as it supports 10 Gbps up to 55 meters and balances performance, cost, and future-proofing. Avoid stranded cable for in-wall runs since it is designed for short patch cables.
Do I need fire stopping when running cable between floors?
Yes. Any hole drilled through a top plate or bottom plate that penetrates between floors must be sealed with fire-rated caulk or putty pads. This is a building code requirement in virtually all jurisdictions. Fire stopping prevents fire and smoke from traveling through the wall cavity between floors. Use intumescent caulk or firestop putty around the cable where it passes through the plate.
Ready to Run Your Cable?
A clean in-wall Ethernet run gives you faster, more reliable networking than any Wi-Fi connection. Get the tools and connectors you need to do the job right the first time.