Wiring an electrical outlet may seem intimidating until you’ve learned the right way to do it. This tabletop demonstration provides a detailed look at how to wire a typical, household outlet including properly splicing ground wires, stripping wires, making the appropriate connections and securing the outlet in the box.
Code and Electrical Permits
Permits: In some areas you are required to obtain a permit for electrical work that includes a new or extended circuit, and sometimes only licensed master electricians can obtain these permits. You can usually find where to file for permits via links on your county government’s or state government’s licensing and permits web page.
Code: Most jurisdictions follow some variation of the National Electric Code. You can get limited free access to the NEC via NFPA’s web site.
About This Demonstration
This tabletop demonstration illustrates one scenario for how an electrical receptacle is wired, and if you find wiring in your home that looks different, that doesn’t mean it was done wrong. Here are some details about this circuit that may differ from other circuits:
Type of Circuit
Most homes feature a combination of 15, 20 and 30 amp circuits, and the appropriate amperage depends on factors like location and power requirements. For instance, many household outlets are wired with 15 amp circuits. However, code requires that kitchen outlets be wired with 20 amp circuits to better meet the need for things such as microwaves. Today’s demonstration shows a 15 amp circuit, and it’s important that the circuit breaker, wiring and receptacle are all rated for at least 15 amps.
Tip: In some cases you can use a 15 amp receptacle on a 20 amp circuit, but not vice versa. Per table 210.21(b)(2) from the 2011 NEC:
Type of Wiring
As you might expect, different amp circuits require different gauge wiring, and this demonstration utilizes 14 gauge wiring. Also, the number of wires found within the sheathing may be different, and that is dependent on the application. For instance, 3-wire which contains a red, black, white and ground wire is used between a pair of switches that control the same bank of lights. Today’s walk-through uses 2-wire.
Tip: Heavier gauge wire is indicated by a lower number. For example, 12 gauge wire is thicker than 14 gauge wire.
Tip: The color of the sheathing usually indicates the gauge of wire. 14, 12 and 10 gauge wire is colored white, yellow and orange, respectively.
The Number of Cables
You’ll see two cables (bundles of wire) in this walk through, and that’s because this receptacle is in the middle of a circuit. If it had been at the end of the circuit, you’d only see one cable, and if the circuit had been further branched, you’d see more than two cables.
Wiring a 15 Amp Outlet
Step 1: Turn off the breaker
If the outlet you’re working on is already connected to the breaker panel, make sure to turn off the appropriate circuit breaker. I like to double-check the outlet with a voltmeter. If you don’t have one handy, just use a lamp (that you know works) to see if the outlet is powered or not.
Step 2: Strip Outer Sheathing
This demonstration assumes that the wire is already run to the box and in through the knock-outs.
To remove the outer sheathing, run a utility knife along the length of wire, and cut the sheathing off just after the cable enters the box.
Step 3: Pigtail the Ground Wire
The outlet only has one ground wire connection so we need to securely splice the ground wires together along with a pigtail to make the connection. It’s a common mistake to think you can just wire nut everything together, and other online tutorials even instruct you to do just that! Here’s the right way to make the splice.
Start by bending one of the ground wires back on itself.
Cut the other ground wire to an equal length.
Use pliers to tightly twist the wires together.
Next, cut the end off.
Lastly, secure a wire nut over the splice.
Tip: Wire nuts are available in several different sizes, and they are commonly color-coded to indicate capacity. Here’s a simplified guide for sizing wire nuts from The Home Depot.
Step 4: Connect the Neutral Wires
Pair up the neutral wires and trim them to an appropriate (equal) length.
You can refer to the wire stripper gage on the outlet to determine how far back to strip the wire insulation. Be careful because you don’t want to expose too much wire.
Grab your wire strippers and remove the insulation, keeping in mind that this is 14 ga. wire. Take care not to nick or damage the wire. If you do, cut the wires back and start over.
Using needle-nose pliers, twist a half-circle in the same direction that you’ll be turning the screw to secure the wire.
Note: Some outlets feature stab-in connectors (in addition to the screw connections) that allow you to push the hot and neutral wires straight into the backside of the outlet.
Loop the neutral wires around the silver screws in a clockwise rotation (the same direction the screws turn), and tighten down the screws.
Step 5: Connect the Ground Wire
Make the same half-circle, and loop the ground pigtail wire around the green ground screw and tighten the screw down.
Step 6: Connect the Hot Wires
Repeat the process of trimming, stripping and securing the hot wires to the gold screws. Notice how there is no excess wire exposed.
Step 7: Secure the Receptacle to the Box
The receptacle has two screws that hold it in the box. Fold all the wires into the box and tighten these screws. Keep the outlet centered in the box.
Step 8: Install Faceplate
Lastly, the faceplate goes on with one flathead screw in the center, and you’re done.