When considering adding an electric outlet in the middle of the run, you might think that the most logical place to put it is either the end of the run or between two existing outlets. However, this may not be a good idea from an electrical standpoint.
The reason for this is because when you wire a middle-of-run outlet with its circuit breaker, you are running 120 volts (or 240 volts) through your home's electrical system which can cause serious problems and even start fires if wired improperly. Before touching any bare wires or terminals on a switch or outlet, use a voltage tester on all the wires to ensure power is off. Here are all the basics you need about wiring a middle-of-run outlet.
Start By Understanding Electrical Project Costs
For safety reasons, wiring a middle-of-run outlet should always be done by an expert who has been trained to do so. But you must also understand that hiring a professional will mean more costs involved. But remember that doing it yourself can help you reduce electrical project costs that you might incur when you hire an electrician. If you have any doubts about your skills or knowledge of rewiring your electrical outlets correctly, then contacting a professional electrician will be worth the cost.
Methods of Wiring Receptacles into Wires
There are two methods of wiring receptacles into the home wiring. First, the circuit can be direct-wired through the receptacle, which means the entry wires can be attached to one pair of hot and neutral screw terminals on the receptacle, while the exit wires can be attached to the other set of screws.
Here, the circuit flows through the receptacle at all times, using the connecting tabs on the receptacle to establish the continuous circuit path. The second method of wiring a mid-run receptacle is to connect the receptacle to the circuit wires with pigtails. This allows the circuit to flow both to the receptacle and to any downstream receptacles without being independent of flowing through the receptacles flowing tab.
Depending on your situation, one of these methods might work better, although pigtailing Is generally preferred.
Why is Pigtailing Preferred?
One drawback to direct wiring through a receptacle is that the receptacle is in the middle of the circuit, and any trouble in the receptacle spells trouble devices downstream. Any problem with the receptacle, or even loose wire under one of the screw terminals, could cause you to lose power to the downstream receptacles.
Direct wiring also complicates repair or replacement because if you want to take one receptacle out of the circuit, you interrupt the remaining downstream receptacles. You must connect the receptacle for the circuit downstream to function again.
With pigtail wiring, these drawbacks are eliminated. A problem or loose of connection with one receptacle will not affect the receptacles downstream. You can also remove the receptacle in the middle of the circuit without affecting the others.
Before You Begin
Before you begin, make sure you have a basic understanding of how receptacles work. On a standard 120 volt receptacle, there are three types of screw terminals. These include brass colored screws that accept black hot circuit wires, silver colored terminal screws that accept white neutral wires, and a green screw terminal that accepts the bare copper wire or green grounding wire.
Just be aware that in old wiring, you may not see the familiar black and white jackets on the circuit wires. It's important to remember that brass screws accept hot wires, and silver screws accept neutral wires. It's possible that in some configurations, a hot wire may be indicated by red insulation on the wire jacket.
What You'll Need
- Replacement receptacle
- Drywall saw
- Voltage tester
- Wire stripper
- Needle nose pliers
- Philips head screwdriver
- Electrical cable
- Modeling box
- Wire connectors
Project Step by Step
Shut Off the Electrical Outlet
Shut off the circuit breaker controlling the outlet you are replacing. Always shut off the power before doing any electrical work, even if it's simple as this one. Once you've determined the electrical outlet to use as a power source and shut it off, use an electric stud finder to locate the studs on both sides. You can put your new outlet anywhere between these two studs.
Unscrew the electrical outlets and use the voltage tester to double that the power is off. With either touching a ground wire, touch the other lead first to the neutral terminals, then to the hot terminals. If the light glows with either contact, their circuit is still live.
Hold the face of the new electrical box against the wall, where you want it to go, and trace around it with a pencil. Use a screwdriver to unscrew the existing outlet on the other side of the wall outlet from its box and punch out one of the knockouts at the back of the box.
Remove the Old Receptacle
Remove the faceplate belonging to the outlet on which you'll be working. Unscrew the two screws holding the old receptacle in the electrical box and pull it forward out of the box. Use a non contact voltage tester to make sure there is no current in any of the wires connected to the receptacle.
Disconnect all the wires attached to the receptacle by unscrewing the connectors and throwing the old receptacle away.
Feed New Cable into the Wall
Remove the outer sheathing on your new cable. Pull about four inches of cable out through the wall using needle-nose pliers. Put the end of the cable into the back of your new electrical box and screw one wire clamp onto each wire coming from the box, attaching it to any one of the screws sticking out from each side.
Connect the New Receptacle
Connect one of the black hot circuit wires to one of the brass colored terminals on the new receptacle, and connect the other black wire to the other brass terminal. Each white wire gets connected to a silver neutral terminal. That leaves the ground wire, which is green or bare copper wire and connects to the green screw on the receptacle.
Insert the New Electrical Outlet into the Wall Box
Press the new electrical receptacle into your junction box and tighten it in with your fingers. It will snap into place as long as you have pushed it far enough inside the box to engage those two plastic ears on its back. Cover it with the faceplate, turn the power back on and check for proper function.
Wiring with Pigtails
Turn Off the Power, Remove Old Receptacle, and Test it
Make sure the power is turned off at the breaker. Remove the old receptacle by unscrewing it with a screwdriver, then pull away the black and white wires still connected to it. Test for power inside the box—if no voltage is present, move to the next step.
Cut and Strip Cable Wires to Length
Cut the NM cable wires to length, then strip about 1/4″ insulation off of each end using a combination tool. Use the utility knife to strip the outer sheath off the cable, exposing the three wires it contains. Use the wire stripper to take off about three inches of the sheathing around the black and white wires.
Line up the black hot wires from the electrical box with the black wire from the NM cable to make the ends even. Twist them together with wire nuts. Do the same for the white neutral wire. The ground wire doesn't need a pigtail, as it can be connected directly to the new receptacle.
This configuration will leave you with both wires from the box and one end of the wire from the new NM cable sealed in a wire nut, for both the black and white wires. There will also be one white and one black wire coming from the wire nut.
Connect the two sets of wires together. Twist one end of an insulated wire around each set, making sure that you have a good connection between them. The black wire goes on the brass screw terminal and the white wire attaches to the silver screw terminal.
Replace the Receptacle
Replace the receptacle cover plate. Pull the ends of each wire back through the box and clamp down a zip tie on them so they stay out of your way. Connect the new wires to the new outlet, including white wire to a silver terminal screw, black wire to a gold colored terminal screw, bare wire to the green grounding screw. Turn the power back on and check for proper function. Finally, call the electrical inspector to check your work.
If you've taken all these steps and your outlet isn't working, turn the power back off at the main electrical panel and call a professional electrician to come out and take a look.
FAQs on Wiring a Middle-of-Run Electrical Outlet
What is a middle of run receptacle?
When an outlet receptacle falls in the middle of a circuit run other than at the end, there are generally five wires at the outlet box. Two cables are hot wires, one bringing power in, the other carrying it onward to the next receptacle. Two cables are neutral and serve the same function.
Does it matter which wire goes wherein an outlet?
As long as they're on a proper terminal, it doesn't matter. The silver terminal is neutral. The yellow or brass-colored terminal is for the hot wire, and the green terminal is for ground. It's not as hard as you might have thought, once you know how to wire an outlet, you can sit back and enjoy without worrying of any electrical danger.
Final Verdict on Wiring a Middle-of-Run Electrical Outlet
There you go. Get rid of those ugly and often dangerous extension cords and wire a middle-of-run electrical outlet. Also, make sure you check with the electrical inspector before using these methods.