Guide To Running Cables Through Walls


Knowing how to connect things inside the light, switch, and outlet boxes is a fundamental DIY electrical skill most men have. Installing all such stuff or adding communication cable like Cat 6 is possible with the ability to “fish” wire through your walls, as the pros say.

You’ll need to run new wires from the power source to your final destination whenever you’re expanding or adding an electrical circuit. In some cases, “pulling wires” through a finished wall can range from a few feet of cable.

The days of tripping over extension cords and strewn wires all over your home are gone. With the right tools and knowledge, you can accomplish anything. Just keep in mind that making mistakes because you’re in a hurry can lead to damage to the walls or electrical wires.

Let’s dig in!

Wire-Fishing Equipment Needed to Penetrate a Wall

You’ll need the following equipment and supplies to run cable through a wall:

  • Pencil
  • Stud finder
  • Drill with a flexible shaft or auger bit
  • Drywall saw or jigsaw
  • NM cable
  • Wire strippers
  • Electrician’s fish tape
  • Cable ripper
  • Electrical tape

First Things First

NM (non-metallic) cable, or Romex, is the most common method for running electrical wires through finished walls. The cable sheathed with the best protective sleeving material is used in a particular circuit configuration, which is critical, as not all of them are the same.

In the first place, the cable’s wire gauge must be adequate for the circuit’s amperage load, and the cable’s conductor count must match that of the circuit. The 15-amp circuits use 14-gauge wire, while 20-amp circuits use 12-gauge.

It is common for the cable to have two conductors, a white neutral and a black “hot” conductor. It will also have a bare copper grounding conductor. This cable is labeled “12-2 with ground” (translation: 12-gauge wire, two conductors, plus grounding wire).

The circuit may only require three conductors and a ground if it is connecting three-way switches or if it is being used for a specific light fixture configuration. The red and black hot wires, as well as the white neutral wire and the bare copper ground wire, are all commonly found in three-wire cables.

Consequently, it is imperative that you have some knowledge of circuits in order to select the appropriate cable for installation. Wiring through unfinished walls (like those in an unfinished garage or attic) or mounting cable directly to the wall may be prohibited by the electrical code.

Individual conducting wires must be routed through metal or plastic conduit or in a metal-sheathed cable called BX cable.

Let’s get started now!

Step 1: Disconnect the Power Supply

Turn off any active circuit breakers in the wall where you’ll be continuing to work for safety. A non-contact circuit tester can be used to verify that the power has been shut off at nearby outlets or switches.

Step 2: Determine the Free Space and the Obstacles in the Way

Check for studs with a stud finder at the desired exit point. No crossbeams or ductwork should be in the way of the wire. If there are any obstructions, such as pipes or studs, that could prevent the wires from passing through, you should drill a small hole for the wire to go through.

Step 3: Make Your Way Over and Under the Spot

It doesn’t matter where in the wall you run your cable; just make sure there’s a clear path to it from both above and below. You’ll need to look for beams in the cellar, attic, or crawlspace to accomplish this. Find the correct location by measuring the wall beam.

If no beams can be seen, look for a feature that can be seen on both sides of the spot and use that to determine its size.

Is there nothing you can do with it?

The distance can be measured by drilling a small hole, threading a thin object, and locating it on the other side.

Step 4: The Drywall Must Go

Cut a hole in the drywall where the wire will exit in the main location. To cut the outline of a rectangle using a keyhole saw, first draw a rectangle and then drill two holes in opposite corners.

Step 5: Drill on the Opposite Side

Drill through the wall plate in the basement, crawlspace, or attic. The hole should be at least 114 inches from the edge when drilling. If this isn’t an option, drill smaller holes further apart to allow for the insertion of the wires.

How to Fish Wire Through a Wall

Once you have prepped the spot, it is time to run the cable through the wall. Here’s how you can do that:

1. Make Use of Fishing Tape When Pulling Cable

The fish tape should be carefully extended from one opening to the next. Tape the fish tape end to the cable with electrical tape. Cables need a smooth surface to move smoothly through.

You don’t want the cable to get jammed or damaged by friction. Ideally, you should have someone on the other end of the cable who can handle the cable with care.

2. Stream a String Down from the Top

You can do reverse work to bring the wire up to a higher surface. To begin, thread a string through the hole and drop a small object through it. Once you’ve made it to the bottom, you’ll need to attach the cable to the string and then raise the string.

3. Make Use of a Magnet

You can use a magnet to run the cable around tricky corners or over long distances. If you want to avoid attracting a metal object along the wall, place the magnet at its stationary end.

Some Major Precautions to Take

In most cities and towns, you need a building permit and an inspection before you can run electrical wires through walls and connect them to devices. As long as the work is done in the homeowner’s residence, many communities allow do-it-yourself electricians to perform this work.

It is imperative that the permit and inspection process not be avoided at all costs. The process is in place to ensure that the work is carried out securely, and the inspector will, among other things, verify that the wire gauge is adequate for the amperage load. Not only this but the wires are routed correctly through the studs.

If you chop off drywall, you should always wear a particle mask and safety glasses to keep the gypsum dust out of your eyes and lungs.

Final Words

Having mastered the art of running a cable through a wall, you now possess the self-assurance necessary to carry out this task. Make sure you have all the required electrical materials and tools. Also, all the stuff should be of the highest quality to prevent any damage or hazard.

Good luck!


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