Home Improvement Expert Danny Lipford

How to Run Wires in Existing Walls and Floors

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Wires running along the floor are unsightly and may pose a safety hazard.

Need a new phone jack in your bedroom or installing speakers for your home theater system? While you could simply string the wires along the floor, it’s best to snake the wires inside walls or under floors.

Wiring new construction before the drywall goes in is a piece of cake compared to fishing them through existing walls and floors. But with careful planning, a few special tools, and the right techniques, running wires in the wall of your home may be easier than you might think.

If you’re not up to the challenge, consider running the wires in special hollow moldings that take the place of standard crown molding or quarter round.

Tools


              Fish tape

Tools needed for running wires:

  • Drill and bits
  • Stud Finder
  • Measuring Tape
  • Flashlight
  • Drywall keyhole Saw
  • Fish Tape or Wire Coat Hanger
  • Electrical Tape
  • String and fishing weight

Before You Start

  • Check Building Codes: Most areas allow homeowners to install their own low-voltage wiring—such as phone lines, computer network cable, and speaker wire—but check to be sure.
  • Select Proper Wire or Cable: Make sure you use UL rated in-wall wiring that meets local building and fire codes—including CM, CMR, or CMP for computer networking, and CL2 or CL3 for speakers.
  • Turn off the Power: Always turn off the breakers in your electrical box before you begin to reduce the chance of an electrical shock should you accidently cut or drill into existing wiring.
  • Avoid Electrical Wires: Keep speaker, computer, and phone wires away from standard electrical wiring for safety reasons and to reduce interference.
  • Choosing Walls: Whenever possible, run your wiring through interior walls, since exterior walls contain bracing and insulation.

Planning

Start by taking some time to consider the best location for the new wire. Eyeball existing electrical outlets, and make sure you’re a safe distance away (the next stud over or more) to avoid interference or hitting existing wires.


Check the attic for unseen problems like pipes and wires hidden in the wall.

Next, examine the location from the attic, crawlspace, or basement to see if it’s accessible and free of hidden wiring or plumbing. It may also be a good idea to scan the wall using a metal detecting stud finder to locate obstacles like copper plumbing pipes and metal ductwork that may be hidden in the wall.

Once your route has been mapped out, calculate the amount of wire or cable you’ll need. Measure the distance from start to end, add a few extra feet for connections, and an additional 10% or so for unexpected problems or obstacles. The last thing you want is to come up short, so allow plenty extra and follow the old adage of “measure twice and cut once.”

How to Fish Wires

  1. When you’re ready to begin, turn off the power and use your stud finder to locate an open area in the wall between the studs.
  2. Drill a small pilot hole where the outlet will be, and use a straightened metal coat hanger to feel inside the wall for any unforeseen obstructions. If you’re looking for an excuse to acquire the latest high-tech tool, a cable mounted inspection camera, such as the Ridgid SeeSnake, makes a great way to see inside a wall.
  3. If everything looks good, enlarge the hole for the wire or outlet box. Be sure to use an outlet boxes that’s made to attach to an existing wall, but don’t install it until the wire has been run.

  4.             Cut hole in wall for outlet.                         Drill hole into wall plate.

  5. Now, go up to your attic, or down to the basement or crawlspace, and drill a hole in the top or bottom wall plate in the same wall cavity as the outlet.
  6. Attach the wire or cable to a fish tape or coat hanger using electrical tape, and feed it into the hole until it reaches the opening at the other end. If you’re working from the attic, you can drop a weighted string down wall cavity, then attach the wire to the string and pull it through.
  7. Run the wire or cable to its destination. This may involve fishing it through another wall cavity, or out a small hole drilled in the floor.

  8.           Drill destination hole in floor.                       Run wire through hole.

  9. Feed the wire through the back of the outlet box, insert the box in the wall, and mount it in place.
  10. Strip the wires and attach them to the wall jack or run them to the device.

Clean Up

If you drilled pilot holes that didn’t work out, patch them with a dab of spackling compound. Sand the patch smooth when dry and touch up with matching paint. Fill any errant small holes in the floor with matching wood putty, and larger ones with a mixture of sanding dust and epoxy glue.



Please Leave a Comment

13 Comments on “How to Run Wires in Existing Walls and Floors”

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  1. krineshen Says:
    June 18th, 2010 at 7:11 am

    is it safe to put electrical wires under marble flooring

  2. Argie Says:
    October 18th, 2010 at 11:46 pm

    What is the best tool to use when snakeing wires behind walls or under carpet?

  3. Official Comment:

    Ben Erickson Says:
    October 19th, 2010 at 7:53 am

    Hi Argie,
    The best tool to use for snaking wires is a fish tape like the one shown in the article above. It’s stiff enough to push through long distances while flexible enough to go around obstructions.

  4. lifton Says:
    February 5th, 2011 at 6:54 pm

    What is an option for wiring inside walls if the attic crawlspace is so small its impossible to go up and drill a hole in the plate?

  5. Official Comment:

    Ben Erickson Says:
    February 6th, 2011 at 8:50 am

    Hi Lifton,
    In fishing wires from the attic where the rafter meets the wall plate, you might have to work from outside the attic by removing a piece of the soffit, or work from underneath (if you’re not on a slab) by drilling through the bottom plate from a basement or crawlspace. Good luck with your project!

  6. Antonio Says:
    March 28th, 2011 at 1:09 pm

    What do you do when you run cable through a hole in the attic and the cable stops on the horizontal stud. Is there a way to still get the cable through the stud or am I going to have to cut out a piece of H. stud from the wall itself, then follow it up with a patch work? If so, what patch kit do you recommend.

  7. Inez Says:
    September 25th, 2011 at 10:49 pm

    Just bought a house and the speakers are installed and there is a box with wires that are seemingly coming from the speakers with wires coming out and I am wandering what do I use to hook the speakers to the television…do I use a amp our a receiver….or are amps and receivers one and the same.

  8. David Says:
    June 29th, 2012 at 10:39 pm

    Inez: speaker wire connects your speakers to your amplifier or receiver. A receiver is just an amplifier with an integrated tuner (e.g. AM/FM)

  9. Richard S Says:
    February 2nd, 2013 at 3:35 am

    I need to run wiring from first floor wall space into basement. How do I locate the 1St floor wall from the basement?
    Thanks

  10. John Says:
    February 2nd, 2013 at 6:20 pm

    Hi,
    I have a 2 floor townhome, built on s slab. I would like to run wiring tho the middle of my room for rear speakers. Any ideas?

    Thanks
    John

  11. Mike Says:
    July 6th, 2013 at 7:16 pm

    Sir
    I need to install security cameras on the exterior wall below eave. How do I run cables for the camera from the exterior wall into the attic directly without penetrating the inside drywall. Thanks!

  12. Josh Says:
    September 13th, 2013 at 8:59 pm

    I’m doing homework for a class, but I have read and re-read the chapter a numerous amount of times with no luck. Maybe someone here can help me? When running concealed cable in an existing home, why is it better to run the cable to the basement rather than the attic?

  13. Brenda Says:
    March 12th, 2014 at 10:30 am

    We are planning on taking up carpet in our den and putting hardwood flooring. Our lamp cords are under our sofa and goes under our carpet now. My question is there a way to put a floor plug in the concrete flooring under our sofa’s and it meet the safety code bore putting our hardwood floor down. What is the cost of doing this if possible or is there another way of eliminating cords being on top of wood flooring where you can’t see them without putting furniture against wall where plugs are? I’m very concerned about this and I really want hardwood instead of having to put new carpet down.Please if possible to let us know ASAP.
    Thank You,
    Brenda

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