How to Run Electrical Wire Behind Walls

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Keep wires concealed and boost your decorating options by running electrical wire behind walls

Running electrical wires behind your walls is a great way to add an additional outlet or switch right where you need it. This project guide will walk you through the steps of running basic nonmetallic (NM) electrical wires behind the walls.

Tips:
• Before beginning your project, decide whether to pull power for your new outlet or switch from an existing outlet or directly from your breaker panel. Either way, double check that adding a new device won’t overload the circuit.
• Diagram your wiring path. Often the simplest approach is to run cables to either the attic directly above the new outlet or switch, or to a basement or crawl space below.
• If you aren’t able to install electrical wires behind walls due to ductwork or plumbing, an alternative solution is to conceal wires using raceway, which runs along the surface of walls and can be painted to blend with your decor.
• Turn off the electricity at the breaker panel to the outlet or circuit breaker you will draw power from. Use a voltage tester to confirm the power is off at the outlet or breaker.
• Make sure a new device will not overload the circuit from which you draw power.

WHAT YOU NEED FOR THIS PROJECT

1
Turn off the electricity
Turn off electricity - Run Electrical Wire Behind Walls

• Turn off the power at the breaker panel to the outlet from which you will draw power.
• Use a voltage tester to check if power is off at the outlet.

2
Mark for the electrical box
Mark electrical box - Run Electrical Wire Behind Walls

• Use a stud finder to ensure the location for your new device isn’t adjacent to a stud.
• Hold the electrical box up to the wall in the location where it will be installed.
• Trace around the box with a pencil to mark the area to be cut. Use a level to ensure the outline is straight.

3
Drill a hole in the ceiling or floor
Drill hole ceiling or floor - Run Electrical Wire Behind Walls

• If you’re running cable through the ceiling, carefully drill a hole with the 1/8-inch drill bit through the ceiling above the new wall box location. If you’re running cable through your basement or crawl space, drill into the baseboard or floor right next to the baseboard instead.
• Insert a stiff wire or straightened coat hanger into the hole.
• In your attic or basement, look for a 2 x 4-inch beam adjacent to the protruding stiff wire. In an attic, this beam is the top of the wall, known as the top plate. In a basement, it’s the bottom of the wall, known as the bottom plate.
• If the 2 x 4 is under a piece of plywood, or covered in some other way,
measure 2 ½ inches from the reference wire toward the 2 x 4 and drill there. That should put the hole in the middle of the plate.
• Check with a flashlight to make sure there are no electrical wires or plumbing pipes behind the walls where you will be working.

4
Cut the opening for the electrical box
Cut opening electrical box - Run Electrical Wire Behind Walls

• Drill a ½-inch starter hole at a corner of your electrical box outline.
• Starting at the hole, cut along the outline with the drywall saw. It’s OK if the edges of the opening are rough. You can conceal the opening with a wall plate.

5
Run the cable
Run the cable - Run Electrical Wire Behind Walls

• If you’re going through the attic, use the spade bit to drill a hole through the top plate, directly above the new electrical box location. If you’re running cable through a basement or crawlspace, drill a hole in the bottom plate directly below the box.
• Feed your fish tape into the wall opening, pushing it up into the hole you made in the top plate. If you’re running cable through a basement or crawl space, push it down to the hole in the bottom plate. You may need to insert the end of a coat hanger into the hole to pull the end of the fish tape through the hole.
• Should you encounter a fire block, proceed with Step 6. If you do not encounter a fire block, go directly to Step 7.

6
How to run wire past a fire block
run wire past fire block - Run Electrical Wire Behind Walls

A fire block is a horizontal beam of wood running between the wall studs. You can drill a hole through the fire block or create a notch to accommodate the wire.

To drill a hole:

• Insert a long, flexible drill bit through the opening for the electrical box and position it on the center of the fire block.
• Drill through the fire block.

To cut a notch:

• Cut into the drywall at the location of the wall block.
• Use a sharp chisel and a hammer to cut a ¾-inch wide x 1-inch deep notch in the fire block as a conduit for the cable. Pull the cable past the fire block following the instructions in Step 7.
• After you have fished the cable through the notch, cover the notch with a metal nail plate to protect the cable from nail damage.
• Patch over the drywall hole.

7
Pull a cable through the wall
Pull cable through wall - Run Electrical Wire Behind Walls

• From the attic, basement or crawl space, use electrical tape to secure one end of the cable to the hook on the fish tape.
• At the wall opening, carefully and steadily retract the fish tape, pulling the cable to the wall opening. Don’t create friction that can tear the cable’s sheathing, and carefully avoid kinks that could damage the cable.