There are two instances in which you would find yourself running wire in walls: when the wiring is either exposed or covered:
Exposed Wire vs. Covered Wire
Exposed: In rare instances, you may be dealing with a permanently unfinished space, such as a garage or shed. For many homeowners, there is no need to close up the walls with a layer of drywall since the space will not be heated or cooled and because aesthetics do not matter.
Covered: The second case, far more common, is when you are running wire in preparation for finishing the room as a living space.
In this case, the wire will not be exposed. This article deals with open walls that are later covered up.
Top Tips For Successfully Running Wire
- SimPull Reduces Friction When Pulling Wire Pulling wire through is made slightly easier with NM wire such as Romex that has a patented coating called SimPull that reduces friction. When Romex owner Southwire conducted tests in Nashville, TN area homes, they found a substantial reduction in installation times.
- Unravel Coils First: Before pulling long stretches of NM, unravel and straighten out the coil first. By doing so, you are not fighting tightly bound wire on a coil, and the pull goes much smoother.
- Nail Guards Fix Mistakes: Metal nail guard plates can be placed over the edges of studs to protect the drilled hole and wiring inside it. This is not required by code, as long as ample distance is provided between the leading edge of the stud and the wire. But if you accidentally bore a hole too close to the leading edge, nail guards let you keep the hole and protect them at the same time.
- Bore Holes In a Straight Line: When augering holes in studs or joists, try to follow a straight line. Any deviation in a straight line makes the pull harder.
- Leave Some Slack: Generally, you do not want to have excess wire hidden in your walls. But it does help to leave a bit of slack in the wires in case you need to adjust your box.
How To Do It
It takes less wire and less effort to run the wire on a wall that will be finished. The reason is because the drywall will eventually cover your work, rendering it free from harm. While running wiring can be done by a skilled do-it-yourselfer, tying the wiring into the service panel (circuit breaker box) and to the outlets and switches is a job best left to a qualified electrician.
- Choosing the Bit: For either 12 or 14 gauge wire, a 1/2-inch or 3/8-inch spade or auger bit mounted on a drill provides a good amount of space to pull the wire through. Larger holes compromise the structural integrity of the stud. Smaller holes make it difficult to pull the wire.
- Where To Bore: 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.
- Attach Boxes: 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.
- Insulation: If you plan 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.
- Contact your municipality and ask for its specific codes regarding electrical wiring. There may be differences from the model electric code.
- Electrical permits likely are required.