How to Run Electrical Wire Through Walls

Any time your project involves extending or adding an electrical circuit, a big part of the job will involve running new wires from the power source to the end destination. “Pulling wires” through finished walls can range from running a few feet of cable, such as when you are extending a circuit to feed an additional outlet in a room, to pulling several dozen feet of cable if you are adding an entirely new circuit fed by the main service panel.

In many ways, running new wire can be the most complicated part of an electrical project, and often the most time-consuming. The most intricate work occurs if you are running cable between house levels, such as from remodeled second-story space all the way down to a basement service panel. It is much less complicated if you are simply extending the cable from an existing outlet to a new location in order to add an outlet. This simpler scenario is what is described in this demonstration project.

Although it does require that you remove and patch some drywall, one of the easier ways to run cable is to simply cut a channel in the finished wall surface, which exposes the studs so you can drill and run the cable. This is the method shown here.

Before You Begin

Running electrical wires running through finished walls is almost always done with a sheathed cable, often known as NM (non metallic) cable, or Romex (named after one of the popular brands). Not all sheathed cable is created equal, and it’s important to choose the type that is right for the circuit configuration. First, the wire gauge needs to be sufficient for the amperage load of the circuit; and second, the cable needs to have the right number of conductors for the circuit configuration.

For a 15-amp circuit, 14-gauge wire is the standard, while for a 20-amp circuit, 12-gauge wire is the norm. For a simple receptacle outlet circuit, the cable will normally have two conducting wires—a white neutral and a black “hot” wire—plus a bare copper grounding wire. This cable usually carries a label like “12-2 with ground” (translation: 12-gauge wire, two conductors, plus grounding wire). But if the circuit is linking three-way switches or is being used for certain light fixture configurations, the installation may call for three conducting wires, plus ground. These three-wire cables generally have two hot wires (red and black) and a white neutral wire, plus the bare copper grounding wire.

Thus, it’s critical that you have some understanding of circuits in order to choose the right cable for the installation.

When cable is being run through walls without finished surfaces (such as in an unfinished garage or attic), or when it must be mounted on the surface of the wall, the electrical code may forbid the use of NM cable. Instead, you’ll need to run the wires as individual conducting wires contained inside metal or plastic conduit, or in a metal-sheathed cable known as BX cable. Those installations are not covered here, as they require different skills.

Safety Considerations

In most municipalities, any work that involves running electrical cable through walls and connecting that wire to devices will require a building permit, as well as an on-site review by an inspector before the walls are closed up. In many communities, do-it-yourself electricians are allowed to do such work, as long as it is being performed in the DIYers home. Sometimes, a short homeowner’s electrical exam is required for the do-it-yourselfer to obtain a permit.

It’s important not to bypass the permit and inspection process. The process exists to ensure that the work is done safely, and the inspector will check, among other things, to make sure that the wire gauge is sufficient to handle the amperage load, and that the cables are routed properly through the studs.

Cutting drywall can throw up some gypsum dust that irritates eyes and lungs, so always wear a particle mask and safety glasses when doing this work.

When to Call a Professional

While running NM cable for new or extended circuits is not a difficult job, the final hookups of outlets, switches, and especially the circuit breaker connections in the main service panel, does require some understanding and experience with electrical work. You may well want to call an electrician to make the final connections if you aren’t fully confident of your DIY skills. Local codes sometimes stipulate that only a licensed electrician is allowed to do work in the service panel.

And you may want to call an electrician for very long or complicated cable runs. A professional has many tools and techniques for running (“fishing”) cables through walls, floors, and ceilings without removing much if any, drywall.

The Spruce / Hilary Allison

Disclaimer: Curated and re-published here. We do not claim anything as we translated and re-published using google translator. All images and Tattoo Design ideas shared only for information purpose.

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