How to Add Electrical Wiring to an Insulated Wall

Investigate to see what pipes or wires already go through the wall. You can't run electrical wires over pipes or other obstructions.

Cut a 1-inch by 1-inch hole in the wall with a utility knife in the location you want to install your electrical box. Feel in the hole for any wires or pipes. If there are already wires or pipes in the hole, patch the hole and cut a new hole somewhere else in the wall. If the hole is clear, trace the outline of the electrical box and cut it out with the utility knife.

Install the electrical box in the hole. Pull the wires through the box and put the box into the hole. Tighten the screws on the front of the box. Open the tabs on the front of the box and insert them into the drywall insulation.

Drill a hole in the wall under the outlet with a flexible drill bit. Be careful not to drill through pipes or insulation.

Push wire fish tape through the hole you just drilled. Have an assistant grab it at the other end and pull it through the hole until about a foot of tape is coming out of the hole.

Strip the insulation from the wire and wrap it around the hook on the fish tape. Put electrical tape over the entire wire and put it back through the hole. Cut off the bent part of the wire and through it away. Repeat steps 4 through 6 for all your wires.

Insulate the electrical box with expanding foam before putting the outlet cover on the box.