Rewiring or fixing an electrical outletcan be simple when it only involves the replacement of an existing receptacle (more commonly known as an outlet or plug socket), but things can get complicated when your electrical outlet installation involves rewiring.
If you're completely new to the world of electrical work or looking to install an outlet from scratch, this is a job best left to the professionals. But if the electrical box has already been installed and you are a confident DIYer with wiring experience, you can use this guide to learn how to wire outlets yourself.
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Before You Begin
Before you start rewiring a wall outlet, it's important to know the two ways you might see them wired from installation. When an outlet falls in the middle of the circuit run, there will be two or three cables in the electrical box. One is bringing power in from your home's electrical panel, and the others are carrying power to other outlets or fixtures.
Tip
A hot wire carries an electrical current from the source to the outlet, and is usually red or black. A neutral wire is white or grey, and lets electrical currents flow back to the source, while a ground wire is green and is in place for safety, causing circuit breakers to trip in the event of an overload.
The first wiring method involves connecting the power supply cable directly to a set of hot (brass) and neutral (silver) screw terminals on the receptacle. The neutral cables are connected to the other set of screw terminals, allowing power to flow through the outlet.
The second method uses short pigtail wires attached to one set of hot and neutral screw terminals to connect the cables. Electricians prefer this method, because power will continue to flow through the overall circuit, even if if an individual outlet is malfunctioning.
If an outlet sits at the end of a circuit run, you'll only see only one cable in the box, and the hot and neutral wires will be secured to one pair of brass and screw terminals.
Safety Considerations
All electrical work comes with inherent risks, so make sure to carefully follow basic wiring practices:
- Before touching any wires, always use a non-contact voltage tester to make sure the power is off. Confirm your tester is working by trying it on an outlet you know is hot—or energized—and making sure it lights up.
- Wire connectionsneed to be made carefully. A wire coming loose from an outlet can create a serious fire orshockhazard. The safest way to connect wires is with an outlet's side screw terminals: amethod known asside wiring.
- Never connect more than one wire to a single terminal. If there is more than one cable in an electrical box, usepigtail wiresto connect the outlet's terminal, or ground screw, to the circuit wires.
- Metal electrical boxes must be connected to the ground system with a grounding pigtail, which links circuit ground wires to the outlet via a green grounding screw. Plastic electrical boxes do not need grounding.
- The receptacle and circuit breaker must have the same amperage rating (typically 15-amps or 20-amps), and the NM (or non-metallic) cable needs to be the right gauge, or size.
- A 20-amp receptacle can be identified by the T-shaped slot on the front of the outlet.
- The electrical code usually requires tamper-resistant (TR) outlets for new installations. These outlets are marked with a "TR" imprint, and stay shut until you insert two prongs from a plugat the same time, keeping children from getting shocked or accidentally inserting any metal into outlet slots.
- Most electrical codes also require the edge of thereceptacle box to be no more than 1/4 inch behind the finished wall surface. If you find out the box is embedded too deeply during your rewiring process, you can install abox extender ringto bring it up to code.
What You'll Need
Equipment / Tools
- Non-contact voltage tester
- Cable ripper
- Cutting pliers or utility knife
- Wire strippers
- Wire connectors
- Needle-nose pliers
- Screwdrivers
Materials
- Scrap NM cable (as needed)
- Outlet receptacle with cover plate
Instructions
How to Wire an Outlet
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Turn Off the Power
- Locate your home'smain service panel, also known as a breaker or fuse box. It's usually in the basem*nt, kitchen pantry, garage, hallway, closet, or on an outside wall.
- Turn off the circuit by switching off the corresponding circuit breaker.
- Make sure the outlet is off with a non-contact voltage tester.
- If you are replacing an existing outlet, remove the old one by unscrewing it from its electrical box, pulling it out, taking a picture of the wires for later reference, and then disconnecting.
Prepare the Cables
- Remove the outer layer of sheathing on the black or red NM cable by slitting the jacket with acable ripper, and trimming away the sheathing and paper insulation with a utility knife or wire cutters.
- If the NM cables are any longer than 6 to 7 inches, trim them down with wire cutters.
Strip the Wires
- Strip away1/2 to 3/4 inch of plastic insulation from the ends of any insulated wires in the box with wire strippers, depending on manufacturer recommendations.
- Make sure the ends of the wires are in good condition. Trim off any nicks or scorch marks, and strip away the insulation from the new end of the wire.
- Many outlet boxes have a stripping gauge imprinted on the back of the device to tell you how far the wires should be stripped. For screw terminal connections, this is usually about 3/4 inch.
Attach Pigtail Wires to Circuit Wires
- Install pigtail wiresif there is more than one cable in the box.
- Cut 6-inch lengths of each type of wire in the cable with a scrap of the same kind of circuit cable.
- Strip one end of each pigtail at 1/2 inch and the other end at 3/4 inch.
- Follow the outlet manufacturer's instructions to join the bare copper (or green insulated) pigtail to the ground wires in the circuit cables, using a wire connector.
- Do the same with the white (neutral) pigtail, then the black (hot) pigtail, so you have one ground, one white, and one black pigtail connected to the circuit wires.
- If the electrical box is metal, install an additional grounding pigtail and connect it to the ground screw on the box.
Connect the Ground Wire to the Receptacle
- Form a J-shaped hook on the end of each wire (or pigtail), using needle-nose pliers.
- Fit the hooked end of the ground wire around the ground screw onthe outlet receptacle The wire should hook clockwise around the screw, and close as as you tighten the screw.
- Use needle-nose pliers to squeeze the hook closed around the body of the screw. Tighten the ground screw with a screwdriver, so the hook fits snugly around the screw.
Attach the Neutral and Hot Wires to the Receptacle
- Connect the white neutral wire or pigtail to one of the silver (neutral) screw terminals on the outlet, hooking the wire clockwise around the screw terminal.
- The neutral wire's insulation should just touch the screw terminal.
- Connect the black hot wire or black pigtail to one of the brass (hot) screw terminals on the receptacle.
- For standard outlet wiring, the white neutral wire can go on either of the two silver terminals, and the black hot wire can go on either brass screw terminal.
Attach the Receptacle to the Box
- Gently tug on each wire, to ensure all new connections are secure.
- Reconnect and retighten any loose wires.
- Carefully tuck the wires into the box by gently bending them.
- Press the outlet's mounting strap (the metal strip at the top and bottom) against the box, and secure it with mounting screws on the top and bottom of the box.
- The receptaclecan be oriented with the ground slot (the D-shaped holes)facing up or down, but it's considered safer to have the ground slot on top.
Attach the Cover Plate
- Fit the cover plate over the outlet and secure it with the mountingscrews.
- Restore power by switching on the circuit breaker.
- Plug in an electrical device to the outlet to make sure the receptacle is working properly.
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When to Call a Professional
Homeowners without home wiring experience should always have an electrician completeany service panel connections. Electrical outlet rewiring and installation is doable for a DIYer, but electrical work involving main service panel is inherently risky, so it's best to call a pro if you don't feel completely confident in your electrical expertise.
FAQ
What are the 3 wires in an outlet?
The three wires in an outlet are a black or red hot wire which brings power over from your home's main source, a white or grey neutral wire that sends power back to close the circuit, and a green or bare grounding wire as a safety measure.
Do outlet wires go up or down?
Outlet wires can go up or down, and each direction has its own benefits. Running wires up can help protect against water damage, while running wires down can help with the everyday wear and tear caused by constantly plugging in and removing appliances from an outlet.
How do you tell if an outlet is wired correctly?
You can check if you have wired an outlet correctly with an electrical tester, or by plugging in a device once you have switched the circuit breaker back on.
