How to Add a New Outlet to an Existing Run
Mastered in a Minute: Splicing a new receptacle in the middle of a run is simple.
Adding a new electrical outlet to an existing run is a straightforward process. Here we have an ideal situation—the drywall on one side of the wall has been removed and the wiring is exposed. But, save for installing a new electrical box, the process is largely the same (check out “How to Install an ‘Old-Work’ Electrical Box” to see how to install a new box when the drywall is intact).
To start, turn off the power to the existing outlet at the breaker panel, and test to ensure it’s off.
Then, remove the outlet and detach the wires.
Install the box for the new outlet, remove the “incoming” wires from the old box, and run them into the new one.
Then, cut a new length of the same-gauge cable to run between the new outlet and the old and feed it to the boxes, leaving about 8 in. of new cable in each box.
The cable needs to be secured to the studs, typically with wire staples, within 12 in. boxes that include cable clamps, or within 8 in. of boxes without cable clamps. When adding a new outlet without removing the drywall, there’s no requirement to secure the new cable to the studs.
To wire the new box, splice the wires from the new cable onto the old, along with pigtails that will connect to the new device. It’s best practice to cut the old exposed copper off the old wires and strip a fresh length to attach to the terminals.
Once the wires are connected (bare copper to the green screw, white to any silver screw, and black to any gold screw), fasten the receptacle, and repeat the splicing and connection process in the old box.
To finish, turn the breaker on and test both outlets to make sure everything is wired correctly.