In order to move electricity from its source at the service panel to its destination at a device (light, outlet, etc.), you need to run electrical wire. A wire is the critical and essential link that forms the network between that single starting point and various, scattered end points.
But how do you run the electrical wire? In some instances, you may be dealing with a permanently unfinished space, such as a garage or shed. For many homeowners facing that situation, there is no need to enclose the wiring behind an outer layer of drywall, since aesthetics do not matter. In this case, you cannot use NM (non-metallic) plastic-sheathed wiring (Romex is one well-known brand of NM wire). Plastic-sheathed NM wire is considered to be too fragile to be exposed. You must use either conduit with individual wires inside or metal-sheathed BX cable.
The second and far more common case is when you are running wire inside of closed walls in preparation for finishing the room as a living space. With new-construction homes, the walls might begin as open walls that need to have an electrical wire run through them, then are later closed up by the drywall team. With remodeling, it is common for walls to begin as closed walls that need to first be opened up before wire is run through them.
Permits and Regulations
In most municipalities, any work that involves running electrical wire through walls and connecting that wire to devices will require a permit. In many communities, do-it-yourself electricians are allowed to do work, as long as the work is being performed in their own homes. Sometimes, a short homeowner's electrical exam is required for the do-it-yourselfer to obtain a temporary permit.
Equipment / Tools
- Drywall cutting device such as a manual jab saw, multi-tool, or RotoZip saw (for closed walls)
- Stud finder
- Auger bit
- Safety glasses
- Measuring tape
- Carpenter's pencil
- Shop vacuum
- Dust mask
- Electric wire
- Metal nail guards for the studs
How to Run Electrical Wire
These instructions assume that there is a closed wall between the service panel and the device that will be wired up. Running electrical wire through the walls and hooking the wire to end-point devices is an easy and safe task for a skilled do-it-yourselfer. However, tying the wiring into the service panel (circuit breaker box) and thus electrifying the wire can be an uncomfortable task for many amateur electricians. If you fall in that camp, you can hire a qualified electrician to perform that final step.
Open up the Wall
If the wall is closed up with drywall, you will need to cut into the first layer of drywall to get to the inside of the wall. Mark off a straight line from the electrical source to the destination. Your goal is to cut as little drywall as possible.
- Horizontal: If making a horizontal run across studs (for example, traveling from one outlet to another outlet), mark a section about 12 inches high by the horizontal length you need to cover. This height is necessary so that you can fit your hands and the drill inside the wall.
- Vertical: If making a vertical run, mark a section that is as wide as the space between two studs. Use your stud finder to locate the studs.
For safety purposes, turn off circuit breakers for any associated live wiring in the area. With your manual or electric saw, cut out the section of drywall you have marked. Carefully set aside the drywall section as you can use this later on to repair the wall.
Choose an Auger 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.
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.
Bore the Holes
Attach the auger bit to the drill and drive a hole into the sides of all studs in the intended electrical run. When augering holes, try to follow a straight line. Any deviation from a straight line makes the pull harder. Clean out the wood chips and sawdust with a shop vacuum.
Run the Electrical Wire
Pulling wire through studs 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, Tennessee area homes, they found a substantial reduction in installation times. Other brands of NM wire may offer a similar feature.
Before pulling long stretches of wire, unravel and straighten out the coil. By doing so, you are not fighting tightly bound wire on a coil, and the pull goes much smoother.
Generally, you do not want to have too much 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.
Install outlet or lighting boxes and route wire into them. Leave about 8 to 12 inches extra wire in the box. It will be trimmed down when the fixture is installed—nothing is worse than not having enough wire when installing a fixture. The wire will be required to be stapled to the stud with wire staples within 6 inches of the box and then every 3 to 4 feet depending on local codes.
Install the Nail Guards
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. If you accidentally bore a hole too close to the leading edge, a nail guard lets you keep the hole and protect the wiring at the same time.
Close up the Wall Again
If you plan to insulate the wall before installing drywall, be sure to leave enough slack in the wiring between the studs so there is no tension when the insulation is put in. Insulation is commonly sliced or peeled in half so the wiring is encased in it, but check with your insulation's manufacturer for their recommendations regarding installation around the wiring. Interior walls need no insulation.
Repair the drywall section by blocking studs with scrap wood to support the patch section. Install the patch with drywall screws. Apply drywall compound (mud) to the area, tape, and let dry. Apply mud a second time, sand down, then apply a final coat of mud. One final sanding should complete the patch job.