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Running Wire in Open Walls

By Kris Jensen-Van Heste

There are two instances in which you'd find yourself running wire in open, or unfinished, walls: Either it's a permanently unfinished space, such as a garage or shed, or you're running wire in preparation for finishing the room as a living space and the wire won't be exposed. The two scenarios call for two very different methods.

While running wiring can be done by a skilled do-it-yourselfer, tying the wiring into the breaker box and to the outlets and switches is a job best left to a qualified electrician.

Running Wire in a Permanently Unfinished Space

Before you proceed, be certain you won't change your mind later and decide to finish the space, because you'll have to redo the wiring. This method requires considerably more wire than what you'd use on a space that will be finished because you're essentially following the path of the wood framing up, down and across. This keeps the wire from spanning open spaces, where it could be snagged and pulled by yard tools or sports equipment in the garage, for example.

What You'll Need

  • Both municipal and national codes require insulated wire, and most commonly used is 12- or 14-gauge nonmetallic sheathed cable known as Romex.
  • Plastic cable straps, also known as plastic staples.
  • Hammer

How to Run the Wire

  1. Plan your wiring layout. First, decide where you want electrical boxes (for outlets and switches). Attach the boxes, whether metal or plastic, to the studs with nails.
  2. Begin working at the box closest to your electrical breaker box. Run the wire through the box and out the side hole in the direction of the next box. Leave enough wire to reach the breaker box, plus at least another foot, for later connection.
  3. Secure the cable to the very center of the wider face of the studs within 12 inches of each box and at least every 4 feet with plastic cable straps, also called plastic staples. Be extremely careful not to nail through the wire itself. Wherever the cable doesn't snug up to the wood, secure it with an additional strap. All wires must be at minimum 1-1/4 inches from the front and back edges of all studs and joists.
  4. At the top of the stud, route the wire up to the header (the piece of wood that runs across the top of the studs) and across its face.
  5. To move horizontally, bring the wire up to the face of the header atop the stud, then staple it as you carry it across until you reach the stud that bears the next box. Choose the shortest route possible, of course, to the next box, running the wire against wood. Keep the wire as protected as possible - and as visible and accessible as possible.
  6. Continue stapling the wire until you reach the next box.
  7. Snake the wire into the box and out through the front about 10 to 12 inches, then double back , leaving about 20 to 24 inches total, and run the wire out of the box toward the next one, keeping the wire securely stapled to the wood.
  8. Travel back up to the header and on to your next box.
  9. To cross the ceiling, travel with the joists, not across them, securing to the wider, vertical side of the joist. You don't want wire without wood to support it.

Running Wire in a Space to be Finished

It takes less wire and less effort to run wire on a wall that's going to be finished. The major difference in this case is that it's perfectly fine to span the space between the studs with the wire, since it will be enclosed and won't be in danger of being snagged or pulled.

To run wire across the studs:

  1. With a 1-inch spade bit mounted on a right-angle power drill or standard drill with a right-angle attachment, bore a hole through the wide face of the stud. The hole needs to be at least 1-1/4 inches from the front edge of the stud to meet code requirements and to prevent accidental contact when the drywall goes up. There are no rules regarding how high you place the hole and wiring - the best route is the one that leads directly to the next box.
  2. Following the steps above, install the electrical boxes. Instead of following the perimeter of the framing, just run the wire through each hole, spanning the space between the studs.
  3. If you're going to insulate the wall before installing drywall, be sure to leave enough slack in the wiring between the studs so there's no tension when the insulation is put in. Insulation is commonly sliced so the wiring is encased in it, but check with your insulation's manufacturer for their recommendations regarding installation around the wiring.
  • It's imperative that you contact your municipality and ask for its specific codes regarding electrical wiring. There may be differences from national code, and you don't want unpleasant surprises later.
  • Find out if permits are required.
  • Metal nail guard plates can be placed over the edges of studs to protect the drilled hole and wiring inside it.

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