How to Wire Electrical Outlets - DIY Receptacle Wiring of Electrical Outlets

Buying and installing electrical outlets

Installing an electrical outlet, even a GFCI outlet, is not a difficult task - the hardest part may be deciding which one to buy! There are literally dozens and dozens of possibilities, but only one or two are correct for any given application.

This article will walk the homeowner through not only how to install electrical outlets, but the purchasing as well. It is not intended to cover all the possibilities of receptacles to be installed and wired, only the normal, common types of outlets found in residential homes. The duplex (two spots to plug a cord into) in both 15 amp and 20 amp ratings as well as the GFCI (or GFI as it is often called) outlets will be discussed. Simplex outlets (one spot to plug into) are wired the same as the duplex outlet.

If you are installing a new outlet rather than simply replacing an existing one, please read the article about adding a new outlet; it contains tips and suggestions for pulling wire as well as wiring the new outlet into an existing circuit.

Electrical outlets (receptacles)

Various outlets.  Only the top three will be discussed
Various outlets. Only the top three will be discussed
A 20 amp GFCI outlet.
A 20 amp GFCI outlet.
15 amp (gray) and 20 amp (white) outlets.  Note the difference circled in red.
15 amp (gray) and 20 amp (white) outlets. Note the difference circled in red.

Choosing a new receptacle outlet

While there are many choices of new outlet, there will only be one or two that are a good choice for any give location.  Primary considerations include the following:

  • Amperage. When installing a new electrical outlet the amperage must be considered. A 15 amp circuit should have only a 15 amp outlet on it. A 15 amp outlet may be placed on a 20 amp circuit as well, but 20 amp appliances will not plug into it and the value of the greater circuit ampacity is, to a large degree, lost. Never, never install a 20 amp outlet onto a 15 amp circuit - 20 amp appliances will trip the circuit breaker or fuse and could cause fires. A good indication if the circuit ampacity is to inspect existing outlets (the picture to the right indicates the difference in outlets) but a better method is to look at the circuit breaker or fuse that is feeding that circuit. Each will have the ampacity of the circuit stamped on it.
  • GFCI outlet. These are more square looking outlets that have two small buttons on the front to test and reset the shock protection they offer. Any outlet installed within 6 feet of a water outlet such as a sink or tub must be GFCI protected, as must outlets installed in garages, outdoors or other "non-living" spaces. A possibility to look out for here is that the outlet being changed is protected by a GFCI outlet "upline" from it. If a different GFCI outlet that trips off also shuts off the outlet being replaced it is already protected and a normal outlet may be installed. GFCI outlets cost considerably more, but how much is your safety or life worth? Use one if necessary, and always replace a GFCI outlet with the same thing. In addition, any outlet being replaced that does not have a ground wire (either bare or green) connected to it must be replaced with the GFCI variety with a sticker attached indicating that there is no ground wire (stickers come with the new outlet).
  • Color. A purely personal choice, of course, and not a requirement. There are many colors commonly available including ivory, white, gray and black, but more are available by special order. Cover plates are also available to match the outlet color.
  • Style of outlet. Both regular and "decora" styles are commonly available. The decora designation refers to switches and receptacles of the square appearance (a GFCI looks similar, with buttons added to test and reset it).

Removing the old outlet

Old outlet pulled from wall and being tested.  It's still hot!
Old outlet pulled from wall and being tested. It's still hot!

Removing any old electrical outlet that is being replaced

If the task involves replacing an old outlet, that outlet must be removed first. Turn the power off before doing any work! A loud radio plugged into the outlet in question may help if the circuit breakers are not labeled properly. After turning the power off, check the outlet again, preferably with a plug tester or non contact voltage detector. Make sure it is off - being shocked is no fun, but there is no reason to suffer that indignity if you are careful about removing power before working on it. The picture to the right shows an outlet pulled from a pegboard wall that is still powered on.

Remove the cover plate and the two screws, top and bottom, that hold the outlet in place and gently pull the outlet out from the wall. If a voltage detector is available now is a good time to check once more for the presence of voltage on the wires. If the outlet is switched, and particularly if a switch controls only half of it, make careful note of which wire goes where. Label them with a piece of tape or other method and make a drawing of which wire goes where. Also label the wires to any GFCI that has more than one white, black and green wires attached to it. Wires to a GFCI outlet must go to the "line" and "load" terminals so if there is more than one set of wires label which set (white and black) is "line" and which is "load".

Take note of whether or not the existing outlet has a ground wire (bare or with green insulation) connected to it. If not, and there is no ground wire in the box, a GFCI outlet must be installed (this is assuming that an "upline" existing GFCI outlet does not already protect it - as noted above that should have already been checked for).

If wires are connected to the screws on the side of the outlet loosen the screws (they should not come completely out) and remove the wires. If the wires are plugged into the back of the outlet there will be a small slot or hole next to the wire - insert a small screwdriver or other tool into the hole and while pressing in pull the wire out of it's hole. It may take a little pressure with the screwdriver to do this. If the wire can't be removed by this method, simply cut it off with wire cutters and strip about ½" of insulation so that once again the end of the wire is bare of insulation. Remove and discard the old outlet.

Wiring the new outlet

White and brass screws for white and colored wires.
White and brass screws for white and colored wires.
Small screwdriver resting on the tab to be broken off of a "switched" outlet.
Small screwdriver resting on the tab to be broken off of a "switched" outlet.

Installing and wiring the new electrical outlet

The next step is wiring and installing the new electrical outlet. If the old outlet was switched on just the top or bottom half, the new outlet must be prepared for that function as well. On the side of the outlet, between the two wiring screws, is a small tab connecting the two screws. The picture to the side shows such an arrangement, with a small screwdriver resting on the tab. Break the tab off so that the two screws are no longer connected.  Normally, only the tab between the brass screws is broken off - the tab between white screws is left alone.  Check the original outlet and prepare the new the same way.

Connect the wires to the new outlet. The ground wire (bare or insulated with a green color) goes to the green screw, usually near the bottom of the outlet. If by chance there is a ground wire in the box but it was never connected to the old outlet it must now be connected. An additional 6" piece of wire may be necessary to connect between two or more ground wires already in the box and the outlet. If so, add it by removing the wire nut holding the two existing ground wires together, add the new "pigtail" and replace the wire nut. Bend a small hook in the stripped wire and wrap it around the screw in a clockwise direction. If wrapped in the wrong direction it may tend to come off when tightening the screw. Tighten the screw firmly.

The white wires go to the white colored screws, or can be plugged into the back of a 15 amp outlet. Make sure they are plugged into the holes nearest the white screws. Black or other colored wires go to the more brass colored screws (or holes) on the other side. If you are looking at the front of the outlet, black wires go to to the right side. If the outlet was switched on either the top or bottom the black wires still go to the same side, making sure that the labels previously applied to the wires go to the same place. If labels have come off, the worst that can happen is the the switched part will reverse from top to bottom or vice versa, so don't worry too much about it.

Wiring a GFCI outlet

The back side of a GFCI outlet.  Click the photo to enlarge.
The back side of a GFCI outlet. Click the photo to enlarge.

Wiring a GFCI outlet

The back side of the GFCI outlet has two sets of screws or holes to use. One set is for the "line" side and one for the "load side".

Line side screws are for GFCI outlets that are stand alone outlets; they do not protect any "downstream" outlets. If you are replacing an old outlet without a ground wire and have more than two white or two black wires in the box, these wires will have to be "pigtailed" to the new GFCI outlet. To do this both white wires need to be connected together using a wire nut, along with a new 6" piece of white wire. All three white wires will be fastened together with the wire nut. The same thing must be done with the black wires. The new pigtails are now connected to the "line" side of the GFCI outlet with the white wires going to the white screws and the black wires going to the brass colored screws. Small lengths of wire are usually available to home improvement stores such as Home Depot.

Alternatively the new GFCI may be used to protect "downstream" outlets as well as itself - this is the preferred option. To accomplish this a tester, preferably a non contact voltage detector, will be necessary, as will some wire nuts. Separate all the wires in the box from each other if they aren't already separated and put a wire nut on each individual wire to cover any exposed copper wire. Turn on the power once more and check to see which wire is "hot" - that is, which wire is now powered. Mark that wire, being careful not to dislodge the wire nut; that wire will be the "line" side of the GFCI outlet.

Turn the power back off and verify with the tester that it is off. Trace the marked, black, wire into the box to find which white wire goes with it. Most houses use wiring in cables that have one white and one black wire; you are looking for the white wire that is cabled with the marked black wire. That white wire is also the "line" side of the new GFCI and will be connected to the white screw marked "line" on the GFCI outlet. The marked black wire will be attached to the brass screw marked "line" as well.

The remaining white and black wires are connected to the "load" end of the GFCI outlet (these screws are normally covered with a caution tape from the factory and such tape must be removed, but the outlet is also stamped with the words "line" and "load"). Electrical code requires that all outlets now protected by the new GFCI be labeled as such; stickers should have come with the new outlet. If there is no ground in the box, all the outlets must also be labeled with a "no ground" sticker.


Outlet Testers

Complete the job

Fold the wires neatly back into the box and push the electrical outlet into the box as well. The outlet is attached with two screws, one each at top and bottom - very occasionally the plastic boxes used in residential wiring will have the threads stripped out of the screw holes. Not to panic - a 1" long #8 sheet metal screw will work as well, although it cannot be repeatedly removed and put back without again stripping out the hole.

Attach the cover plate and turn on the power. It is best to check the new outlet with an outlet tester - these are small inexpensive testers made just for testing to see if an outlet is wired correctly.

Congratulations: you have learned how to wire and install a new electrical outlet and done it yourself! Another home repair task completed with a minimum of fuss or bother. If this task seems beyond your ability, I suggest you check out "Learning to do home repairs" by Wilderness. Of possible interested is also a hub recommending tools for the new homeowner as well as instructions for replacing a light switch or a new light fixture. Both are simple tasks as well, easily accomplished by the average homeowner.

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Comments 26 comments

J Sunhawk profile image

J Sunhawk 5 years ago from South Carolina

Great Hub. I've been looking at my outlets and they need replacing. Now I have a place to go when I need to do electric work - your hubs.


wilderness profile image

wilderness 5 years ago from Boise, Idaho Author

Thank you for the comment and compliment.

I have done and continue to do a good deal of electrical work and enjoy sharing my experience with others. If you come across a task I've not explained, drop me a line and I'll try to help out.


CSHandyman profile image

CSHandyman 5 years ago from Jacksonville Florida

Thank you for the information. I do handyman work on residential homes and any type of home repair or replacement article is very helpful to me. I will check back often.

http://www.cshandymansvc.com


wilderness profile image

wilderness 5 years ago from Boise, Idaho Author

You are certainly welcome, and I hope you find this hub and others on home improvement helpful.

Replacing electrical outlets is something that many people don't realize is necessary as homes age. Outlets do wear out and occasionally need replacement.


whitton profile image

whitton 5 years ago

Nice Hub. Very helpful information. I think a couple of my outlets are needing some replacement.


wilderness profile image

wilderness 5 years ago from Boise, Idaho Author

That is quite possible. Over time heat and simple age decrease the spring tension in the outlet, leading to increased resistance and more heat, producing more loss of tension.

If the plug feels loose or tends to fall out it needs replacement.


Don 5 years ago

I've replaced the gfci outlet and it still does not work. Any other suggestions?


wilderness profile image

wilderness 5 years ago from Boise, Idaho Author

Don, there aren't a lot of options at this point. You could have a defective GFCI - I have seen this happen - but that would be unusual. I assume that you replaced a GFCI with a new GFCI, but if not, is it possible that an "upstream" GFCI was providing protection for the old outlet? You can put multiple GFCI outlets on one circuit, but ONLY if you pigtail each box so that one GFCI does not feed the next one via the "load" screws.

Are you sure that you wired it properly? Incoming power should go to the "line" screws, not the "load" screws. "Load" screws typically have a piece of tape over them from the factory, but they should also be marked.

If you pigtailed wires in the box to provide a single wire to the new outlet, are the connections (white, black AND ground) good? If they were already pigtailed it is not unusual to pull a wire out of a wire nut when installing a new outlet and not notice it.

More likely is that it is not getting power. If you have a non contact voltage detector you can open the box and check for this, if not turn off the circuit that feeds it and note which outlets are near it on that circuit. Be aware that they could well be on the other side of a wall, so check for outlets in adjacent rooms on that circuit. Open each one and check connections.

The bottom line is that if there is power in the box, then the problem is probably in that box. It is possible that the white wire is disconnected somewhere upstream, however, so be aware of that. If there is no power, you must trace the problem to whatever box it stops at and correct it.


Carly 5 years ago

I am trying to find out if I can run an outlet from a light switch. THe current light swith has only three wires one in each color(white, black, ground). Can I do it? or do I need to run the outlet from the ceiling light? Thanks


wilderness profile image

wilderness 5 years ago from Boise, Idaho Author

No. Not unless there are additional wires tucked back into the box that you aren't seeing.

There would have to be two cables, both with a black, white, and ground with the two whites spliced together and never terminating on the switch.

From your description there is no neutral in the box; this is a very common and well accepted practice. Without a neutral you cannot run an outlet from the switch box.

You will have to run the outlet from the ceiling light (or another outlet), using the white that also feeds the light fixture. The cable going to the switch will contain a wire to the light fixture as well; the black you need for the outlet will be the other wire to the switch.


glassvisage profile image

glassvisage 5 years ago from Northern California

Holy moly! This is quite an undertaking, but you've really explained it well, and the photos are very helpful too. This is some great information!


wilderness profile image

wilderness 5 years ago from Boise, Idaho Author

Actually, it's not nearly as difficult as it looks. Glad the hub and photos helped, though - thanks for letting me know.


hhalpacas 5 years ago

Hello all. putting in new wiring in a barn. 15 amp and running only a couple of 2 plug outlets. when wiring the (quads as i call them) i am connecting to the ground with the main run to the box, do i need to run a jumper from the second ground also, or is it grounded by the other. thanks.


wilderness profile image

wilderness 5 years ago from Boise, Idaho Author

If I'm understanding your question, the acceptable method is to bring the incoming power into the box with two duplex (common) receptacles. At that point splice two more small lengths of ground wire onto the ground on the incoming cable, and run one of the spliced pieces to the ground terminal on each receptacle.

If you are using a metal box and romex (common house wiring) or MC cable you are also required to add a third ground to the pair you spliced on and terminate it on the box itself. Even if the box is screwed to metal framing in a barn or other metal structure it is not considered to be grounded until the incoming ground is screwed to it - there is a threaded hole in the box for that purpose. A plastic box will not, of course, require a ground wire to the box, just to the receptacles.

If your barn is used to house animals it could require an extensive, very specific, grounding system as animals are very susceptible to stray current leakage through the earth (cows, for instance, may have a dramatic decrease in milk production). If this is the case, the best bet is to contact an electrician as the requirements can be complex.


Whitney 4 years ago

I'm changing out worn receptacles in my parents new house. When I pulled out the receptacles in a basement bedroom, I found the hot and neutral wires plugged directly into the back of the unit rather than connected to the sides with screws. I haven't managed to figure out how to disconnect the wires from that box without destroying something and I can't find any reference online for this type of box. The house was built in 1986 but we don't know when the basement was finished. What is this receptacle and how do I change it?


wilderness profile image

wilderness 4 years ago from Boise, Idaho Author

Hi Whitney!

These are very common, inexpensive outlets often used in homes. To remove the wire from the outlet, look for either a slotted or round hole in the back of the outlet. Insert a small screwdriver or a piece of stiff wire into the hole; it will release the catch holding the electrical wire and you can simply pull the electrical wire out.

If all else fails and you simply can't get the wires out of the old outlet, simply cut them off and strip the insulation from the last 1/2 or 3/4 inch. You SHOULD still have plenty of wire to terminate on a new outlet. If not, an additional 6" piece of wire may be connected to the original wire using a wire nut and will provide plenty to hook to a new outlet. It won't be real easy, but it can be done with only a couple of inches of old wire way back in the box. Just be very sure to tug firmly on each wire in the wire nut, trying to pull it out of the wire nut, before mounting the outlet to the box. The object here is to make SURE that the wire nut has a good hold on all the wires in it.


Jennifer 4 years ago

Hi I have a fairly new home. Did some rearranging in a room and when I went to use an outlet, I discovered it did not work. It is the only one in the house doing this. I went to replace the receptacle which only has one black, one white, and the ground wire. Even after replacing it it still does not work. Any thing I can do?


wilderness profile image

wilderness 4 years ago from Boise, Idaho Author

Sounds like one of three things. Either that plug is being protected by a GFI outlet somewhere "upstream" (closer electrically to the breaker panel) and that GFI is tripped, the outlet is switched and you haven't found the switch, or there is bad "makeup" upstream.

GFI breakers are commonly used in kitchens, bathrooms and garages. Is this one of those, or perhaps a converted garage? Is it in a room that used to be a porch (outside outlets must also be protected by a GFI)?

How about a switch you haven't found? Switched outlets are common in living rooms or perhaps family rooms.

Finally, there is a bad connection either buried in the box behind the outlet or in one "upstream". Check that there is indeed no power to the outlet with a non-contact voltage detector or a voltmeter. Turn off the breaker that provides power to the rest of the outlets in that room and check that each and every wire in each box is spliced correctly, either with a wire nut of with two wires going to the same place on the other outlets. Any one of them could be loose, causing that "downstream" outlet to go dead.

If none of this works, please email me with more particulars - what room is it in, about how old is the house, is there power in the box (very rare, but a brand new outlet could be bad), has it been remodeled, are there other outlets on the same wall, etc. and I will give it another try.


Brian 4 years ago

I have a similar situation to the one about 4 months ago:

"You will have to run the outlet from the ceiling light (or another outlet), using the white that also feeds the light fixture. The cable going to the switch will contain a wire to the light fixture as well; the black you need for the outlet will be the other wire to the switch."

The wiring direction is not clear to me. I want to run an outlet off a ceiling light with a switch on it. The problem is that my first attempt would turn the electric off to the outlet AND the light (I want to leave the outlet 'hot')


wilderness profile image

wilderness 4 years ago from Boise, Idaho Author

I understand - you have the reverse of the same problem that Carly has.

It sounds as if you have wired the new outlet to the same wires that the light fixture uses; the "hot" wire is switched and this will turn off the outlet every time the light goes off.

If there is only one cable in the light box you are out of luck; the "power" cable is going to the switch first and the only thing available at the light is going to be a switched wire.

If there are 2 cables in the light box (2 blacks, 2 whites) you may be all right (assuming there aren't two light fixtures operating off of the one switch and the other cable simply feeds the other fixture). One of those cables will be "hot" at all times.

If this is the case, one of the black wires will be spliced, probably with a wire nut, to either another white or black wire (it will not go to the light) from the second cable. The white wire from the same (first) cable will go to the light. This is the black wire you want; splice your new black wire going to the outlet into the same wire nut. The white wire to the outlet will go to the same white wire that goes to the light fixture. Be sure all the ground wires are spliced together.

If this is not possible you will have to get power either from the switch or from another outlet. If there is only one switch in the switch box (it isn't a set of several switches all in one box) this is quite possible. In the switch box you should find two cables, each with a black and white. The whites should splice together and not terminate on the switch. Each of the black wires will go to the switch: one is hot all the time, one is switched and goes to the light. You will either have to test this with a voltmeter or simply use trial and error. To use the hot wire in the switch box, run the new outlet cable to the switch box, cut an additional 6" piece of black wire and splice the new black wire, the permanent hot black wire and the six inch piece all together. The other end of that 6" piece goes to the switch where the permanent hot was. All the whites splice together. Another article,

https://dengarden.com/home-improvement/adding-elec...

gives tips on running new wire into existing boxes, whether they are switch boxes or outlet boxes.


Brian 4 years ago

There is only one wire in the light box, so I guess it will always be switched, if I tap in there. I kind of have to use that power source ( at the light) - I did it over the holidays for a 'village' power source, and just unscrewed the lightbulb and put tape over the switch to keep it 'on'.

If I go into the switch, is there a way I could use the wire that goes to the light as a 'hot' wire to power both? Would a pigtail at the switch do the trick? How would I wire that? Then at the light - I would just tieall 3 blacks together, all 3 whites together and all 3 grounds together, correct?


wilderness profile image

wilderness 4 years ago from Boise, Idaho Author

If you run your new wire into the switch, you may get power there as mentioned in my earlier post. If you must run the wire into the light, you can go into the switch and take the wires off the switch and splice them together, although this will disable the switch and turn the light on all the time. Maybe install a fan/light combo with a remote control? Or a cheap ceramic fixture with a pull chain?

And yes, if you disable this switch this way you sill simply tie all the blacks at the light together, all the whites together and all the grounds together.


Brian 4 years ago

Thanks for all your help on this. I don't want to remove the switch...I was wondering if there is a way to use the current wire that is there to run a constant hot line for the outlet and light switch in the ceiling area by pigtailing at the switch...so that I would have the best of both worlds, but running another wire back to the switch area is out of the question. I'm probably trying to do the impossible, but thanks for your help.


wilderness profile image

wilderness 4 years ago from Boise, Idaho Author

Perhaps I misunderstand; if there is a wall switch you can disable it removing the wires from it and splicing them together. This will leave the light on at all times, but a pull chain could be added at the light to turn it on and off. It will also provide a constant hot at the light box that could be used to power an outlet as well as the light with a pull chain. The now disabled switch can stay in the wall for appearance sake, but it will not control anything.

What you cannot do is use the wire between the switch and the light to provide BOTH a switched and constant hot wire. That takes three wires; a neutral (which you have), a switched wire (which you have) and a third, unswitched, wire (which you do not have).


cablez1122 4 years ago

Useful information and a must for everyone to know about these electrical outlet


wilderness profile image

wilderness 4 years ago from Boise, Idaho Author

Thanks, cablez. We all have outlets in our homes; it can pay dividends to understand a little about them.

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