Electrical Outlet wire connections (C) D FriedmanElectrical Outlet Installation Wiring FAQs
Questions & answers on how to wire an electrical receptacle, wall plug outlet: complete installation details

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

How to install an electrical receptacle - electrical outlet wiring procedure:

Starting here, this article series describes how to choose, locate, and wire an electrical receptacle in a home. Electrical receptacles (also called electrical outlets or "plugs" or "sockets") are simple devices that are easy to install, but there are details to get right if you want to be safe.

This article series explains eletrical receptacle types (also referred to as wall sockets, outlets, or "plugs" by non-electricians), receptacle grounding, connecting wires to the right receptacle terminal screws, electrical wire size, electrical wire color codes, and special receptacles for un-grounded circuits.

Green links show where you are. © Copyright 2017, All Rights Reserved.

Electrical Outlet Wiring FAQs: questions & answers on wiring & DIY Repairs

Reader Question: what's the difference between "line" and "load" terminal screws on electrical receptacles? How do I hook up a quad of four receptacles to an existing circuit?

GFCI wiring details, back view (C) Daniel FriedmanWhat is the difference between the load and line terminal screws on a 15 or a 20 amp receptacle? How do i wire 4 more receptacles to an existing receptacle in a room? - Anon

This question was originally posted at BACK-WIRED ELECTRICAL DEVICES.

Reply: how to wire line and load terminals on receptacles (outlets)

Anon: the line and load electrical wire connections are important to get right on certain electrical devices such as GFCIs and AFCIs. Our photograph (left) illustrates the line and load markings on the back of a GFCI electrical receptacle.

Looking at the side or back of the molded case of this and other electrical devices such as AFCIs, you will see that one pair of terminals will be marked "line" and the other "load".

Which wires connect to the "Line" terminals:

The Line terminals (green arrows in photo at left) on an electrical receptacle are for the incoming hot wire - the terminal marked LINE is connected to the incoming power source or the "hot" wire (typically black or red in insulation color) that connects to the brass colored screw (marked "Black" or "Noir) at the lower left " in our photo.

And the incoming neutral (white) wire from the electrical panel connects to the "Line" and "White" or "Blanc" terminal marked at the lower right in our photo

Which wires connect to the "Load" terminals"

The Load terminals (red arrows near the top of our photo at left) on an electrical receptacle are for the outgoing wires. These wires feed electrical receptacles that are located "downstream"(farther from the electrical panel) from the device. The outgoing hot or black wire (red arrow, above left in our photo) connects to the terminal marked "Load" or "Charge" and "Black" or "Noir". The outgoing white, neutral wire, connects to the terminal marked "Load" or "Charge" and "White" or "Blanc" in our photograph.

Re-stating, terminals marked LOAD on a GFCI or AFCI are intended to be used to feed other devices (such as receptacle) that are wired "downstream" from the one being worked-on. In a string of electrical receptacles wired in series, incoming electrical power flows in to the first GFCI/AFCI receptacle and is connected to the LINE terminal. The LOAD terminals of that device are connected to hot and neutral wires that subsequently are connected to the next electrical receptacle in the series.

To hook up a quad of electrical receptacles you'll need a larger junction box. And often we wire two separate electrical circuits to the box, placing one pair of receptacles on one circuit and the other on the second circuit - that approach allows us to plug more devices into the wall at that location with less chance of overloading a single electrical circuit in the building.

Watch out: while a conventional receptacle may work with the line and load terminals reversed, a GFCI or AFCI will be unsafe if wired with that mistake, and those devices will not work properly nor test properly in all circumstances. For example, if you connect the incoming "hot" wire and neutral wire to the "load" terminals on a GFCI, and if you connect wires leading to downstream electrical receptacles to the "line" terminals (these are the incorrect connections), then pushing the test button on the GFCI will not activate that device's internal trip mechanism.

Reader Question: can I connect a pigtail from multiple hot, neutral, or ground wires over to a receptacle

Electrical receptacle mounting strap and screw are not a ground (C) D Friedman

I have 2 receptacles that are both side and back wired, 3 hot and 3 neutral wires. I eliminated one receptacle (capping the 3 wires together) but want to keep the other. Is it safe to just run a pigtail from the 3 wires to the receptacle? - Greg

When wiring multiple boxes in series, how do you connect both incoming and outgoing ground wires to the back of the receptacle? With 12 ga. wire, only one wire will fit under the green screw (and not very tightly, at that - there's no washer or clamp.) - Bob M.

This question was originally posted at BACK-WIRED ELECTRICAL DEVICES.


Yes, Greg, that's a common practice. Be sure that your junction box is big enough to contain all of the wires and twist-on connectors.

Bob, similar to Greg's question, I see two approaches to hooking up the ground wire in junction boxes and at electrical receptacles.

  1. If the incoming ground wire from the feed circuit was left long enough, it can be run continuously, connected to a grounding screw that connects the wire to the metal junction box (skip this step if plastic junction boxes are in use), on to the ground screw terminal at each electrical receptacle, and ending with a ground clamp crimp connector that ties the incoming ground to the ground wire of the outgoing wire that continues to the next junction box.
  2. If the incoming ground wire is not long enough to run as above, then an additional length of ground wire is pigtailed to the incoming ground and makes the other connections I've described above.


    Details about back-wired electrical devices (receptacles & switches) are

In sum, all of the grounds are tied together in the box: the incoming ground, outgoing ground, and ground wires to each of the electrical receptacles.

Watch out: while the electrical receptacle ground may also be electrically connected to the metal strap that mounts the receptacle to the junction box (photo at left), and while the junction box may be metal, do not rely on the receptacle mounting screws and receptacle strap-to-box contact to serve as the grounding connection.

It's easy for the receptacle mounting screws to be deliberately left loose or to work loose - making that ground connection unreliable. Use a ground wire.

This article series describes how to choose, locate, and wire an electrical receptacle in a home. Electrical receptacles (also called electrical outlets or "plugs" or "sockets") are simple devices that are easy to install, but there are details to get right if you want to be safe.

Question: how to wire up a pair of receptacles in one electrical box

Quad plex electrical receptacle wiring (C) Daniel Friedman

I would like to wire 2 single plug ins to one live do i do that? - Channing

This question was originally posted at BACK-WIRED ELECTRICAL DEVICES.


Channing, re Hooking up a Pair of Receptacles in One Electrical Box:

If your two plug ins (two electrical receptacles) are located in the same electrical box (we call this a "quad" electrical receptacle installation since each individual receptacle provides connections for two wall plugs), you'll want to wire the hot and neutral to one pair of screws on the first receptacle, and use short black and white jumper wires to connect the the proper terminals on the first receptacle to the second one in the same box.

That's a perfectly acceptable use of the second pair of screw terminals you see on the receptacles.

The ground wire can be continuous, tying the two ground screws on the receptacles together and onwards to the circuit ground.

However a better practice when wiring up a quad-plex of electrical receptacles is to place left and right or upper and lower receptacles on separate electrical circuits - thus reducing the chances of overloading the circuit when many things are connected simultaneously. There are two approaches: you can wire the left and right duplex receptacles each to different individual electrical circuits, or you can wire the upper and lower half of the pair of duplex receptacles to different electrical circuits.

Wiring a Split Receptacle to Two Different Electrical Circuits

Electrical receptacle split receptacle wiring (C) Daniel Friedman

If you choose to wire the upper and lower duplex receptacle openings to different circuits, we call this the "split receptacle" wiring method, because we are splitting the individual duplex receptacle upper and lower connectors onto two different circuits.

Our photo (left) shows an electrical receptacle that is being wired to a single circuit. The white neutral wire is connected to the silver screw (left side of our photo).

If we were wiring this electrical "outlet" as a split receptacle, we'd want to feed the upper and lower halves of the device from two different electrical circuits.

To do so we'd have to break away the "breakaway" connecting tab pointed to by our orange arrow.

Daisy Chaining Receptacles in Separate Electrical Boxes

If your two receptacles are in different locations and thus in different electrical boxes, your circuit that wires the second or "downstream" receptacle can be powered by those same extra terminal screws on the first or "upstream" receptacle. You'll need to run a wire from the first receptacle through the wall into the second electrical box of course.

Wiring Electrical Receptacles on a Single Circuit In Parallel

In some jurisdictions electricians to not "daisy chain" receptacles in the same box together by using the second pair of screws on each one. Rather the circuit enters the box and using twist-on connectors, short pig-tail wires are connected to each receptacle at the proper screws. This approach requires a larger electrical box as it will contain more connections, connectors, and so needs more room.

Question: what is the minimum height that indoor house wiring must be above the ground or floor level?

When running wire for a basement, is there a min height the wires must be off the ground? Not the outlet box, but the wire running through the joists. Justin Sheppard

I was looking at some height requirements on electrical outlets this is a very informational site. - thanks Jerm 4/19/12


No, Justin. But if there is the slightest danger that wires will be nicked by someone driving a nail into a stud though which the wires are run be sure to use steel plates to protect the wire where it passes through the studs. Simple nail plates are available at any building supplier.

Jerm, in the article above at ELECTRICAL RECEPTACLE HEIGHT & CLEARANCES we give the data you want. Let me know if anything is unclear.

Question: how do I get rid of a four-way switch

Wanting to get rid of a four way switch not sure what wires to remove in order to remove the switch. I have three switches to control one light in my kitchen is this what they call a four way switch? Any help would be very helpful - Jim


Jim, once you've got more than one electrical switch installed to control a single device - such as a kitchen light - all of the switches and wiring can be installed using three-way switches. The wiring details are right on the package.

Question: When wiring an electrical receptacle, what do I do with the red wire? Can I ground it?

I have a 3 wire (Black, White, Red and ground) feeding a outlet and I want to add another receptacle to run further down the line. The line out is 14/2. What do I do with the Hot Red wire? Can i attach it to the ground. - Rick

Reply: NO!!


NEVER connect a hot (red or black) wire to ground (nor to the white neutral wire) - doing so would form a dead short, should trip a breaker, or if not, could cause a fire or could cause a dangerous shock.

If there is a hot wire that is not used in a junction box, SOP would be to cap it off with a twist-on connector.

It sounds as if you'd be best served by hiring a licensed electrician.

Reader follow-up:

After capping off the red wire, can I extend the line to the next plug by following the diagram above and adding the black and white wires to the respective second screw connections?

You see, the wiring has already been installed by the builders and they left the boxes without receptacles so all I have to do is connect them to the. I don't know why the extra red wire is there. It was done over a year ago. I want to finish the connections. It runs 14/3 and then 14/2. That's why I have the extra red.

Reply: how three-wire circuits or multiwire branch circuits with a common neutral (and ground) are used and wired

Rick often electricians run a 3-wire system into a building area using two hot wires and a shared neutral, to permit providing two circuits in an area while having to pull just one wire to the area. But to sort out how your wires were connected and are being used requires some expertise, visual inspection, and testing using a VOM.

Take a look at multi-wire branch circuit wiring information and hook-up details at MULTI-WIRE CIRCUITS.

Question: how do I install multiple electrical outlets (receptacles) along a wall?

putting in more than outlet on along a 12ft wall - Mike Tucker


Mike, if your comment is a question of how to put in more than one outlet along a 12 foot wall, yes it's perfectly permitted to exceed the minimum number of receptacles along a wall.

The wiring system is unchanged except that in some cases I recommend installing two different circuits and alternating which outlet is served by which circuit. That avoids overloading one circuit if you are plugging in lots of devices in one area.

Question: Is 14/3 wire ok to use to wire between the light switch and the light? What about an electrical outlet on the same circuit as the ceiling light fixture?

is it okay to use 14/3 wire for power to light to switch to receptacle?



If you are asking about using a shared neutral wire on a lighting circuit combined with an electrical receptacle circuit, see (search for) our article on "multi wire branch circuits" or "shared neutral electrical wiring".

In general we'd use 14-2 wire on a 15 amp circuit to power electrical receptacles and a SEPARATE circuit to power the lighting fixtures. If we lose power on one circuit we want the other still working so that there is safe lighting in the area.

For a light fixture such as a ceiling light, in addition to bringing power to the junction box where the light fixture is to be mounted (using 14-2 copper wire) we'd use a separate length of 14-2 wire to run from the light switch to the junction box to control the light. Tape the white wire at both ends of the switch circuit with black tape so that the next worker knows that this is a switch circuit and that the white wire is not a neutral wire.

Watch out: we do not wire fixed lighting fixtures such as ceiling lights on the same circuit as electrical receptacles ("wall plugs"). If one of the two circuits should be switched off by a circuit breaker (perhaps detecting a fault or overcurrent) we want the other circuit to remain on so that room occupants are less likely to be left in darkness.

Question: how is an electrical outlet wired to the electrical panel?

how do wire the outlet plug to the electrical panel - Anon


Anon, the electrical circuit that powers an "outlet plug" or receptacle is connected, usually through building walls, ceilings, or floors, from the first receptacle in the particular series back to a fuse or circuit breaker connection in the electrical panel. The fuse or circuit breaker, by its connecting mount in the electrical panel, receives electrical power from the income electrical service.

Question: connecting 14-3 to 14-2 wires & to the junction box

How do you connect 14-3 to 14-2 to a junction box - Moe.


Moe, twist on connectors are used to connect the incoming and outgoing hot, neutral, and ground wires, and a single pigtail length in that same twist-on connector can connect the ground to the local junction box.

Watch out: when mixing 14-3 and 14-2 wires on an electrical circuit.

If the 14-3 wires are the hot wires entering the box, and if only 14-2 is leaving the junction box, cap off the unused (typically the red) hot lead.

Do not just bond it together with the outgoing hot wire in the 14-2 group. Making that mistake would short two hot leads together, would be improper, unsafe, and a fire or shock risk.

Question: how to fix loose electrical receptacles in a ceramic tile or glass mirror wall wall

Is there a way to repair electrical outlets on finished (glass and ceramic tile) walls that were not installed properly without damaging the tile? The outlets and the covers pull away from the wall when the electrical cord plug in removed?
Also, what does it mean when an electrical switch with multiple switches which control recessed lights, the ceiling fan and light on the ceiling fan gets hot; what is happening? Is this a fire hazard? - Mrs. Spencer


Mrs. Spencer:

It sounds as if you need a licensed electrician to check and secure your loose electrical outlets - I agree that a loose electrical receptacle is unsafe. But an inspection is needed to understand the underlying problem. It could be simply tightening screws, or it could be that the electrical box itself is not adequately secured in the wall. Luckily there are retrofit parts that can be used and inserted along the box to make it secure, usually without disturbing the surrounding ceramic tile.

Some dimmer switches use a resistor to dim the light and it is common for them to get warm. Very hot - a subjective judgment for homeowners - may indeed be a fire hazard and should be investigated.

Question: I don't have enough wire to lower receptacles on the wall

I recently moved into a 3 1/4 story home, and I have a basement that I am trying to finish with drywall. The room is down to the studs and the electrical receptacles are about 4' up the wall. The Romex wiring is stapled, and there isn't enough wire to lower them. It is way to much work for me to replace all of the downstairs wiring right to the breaker box, so I'm wondering if it is possible to add onto the existing wires and attach wire screws or marrets within the walls before I start adding drywall, or whether I should add some kind of junction box to contain the marreted wires in between. My building code stipulations would differ in some cases because I live in Canada, but I just want to do the job right, and I do not want to take the chance of having any fire hazards, as I also have small children. - Dave 2/10/12

Reply: if you have to move an entire string of electrical receptacles complete re-wiring is faster and cheaper than adding a splice box for every device.

Dave,. you are correct to be careful about moving outlets or any other device when the existing wires are too short. The temptation is to just splice on an extension and bury that in the wall or ceiling: an illegal, improper, unsafe as well as really aggravating approach.

The proper approach is to add a junction box at each splice - we never splice 120/240V wires without including them in a box. You can reduce the wiring work a little by using plastic boxes instead of steel - avoiding having to also connect the box to the ground wire.

The proper approach also means that you don't then bury any of these splice-boxes in the walls either. Each box has to be brought to the surface and covered.

The result is a lot of work and expense and an ugly wall with an extra junction box and blind cover all along the wall over each of the now moved or lowered electrical receptacles.

Frankly I figure that especially as you've already got the wall open to the studs, if there are more than one or two receptacles to be moved you'll probably find it is actually much less total work to re-wire the entire circuit, allowing proper lengths of wires for each box. You might carefully remove and re-route the existing wire lower in the wall or you might buy all new electrical wire - depending on the age and condition of the existing materials.

Watch out: when removing wire that appears to be in good condition, if you nick the insulation you've created a new hazard.

Question: electrical outlet height requirements

I was looking at some height requirements on electrical outlets this is a very informational site.

thanks Jerm 4/19/12


Jerm, in the article above at ELECTRICAL RECEPTACLE HEIGHT & CLEARANCES we give the data you want. Let me know if anything is unclear.

Question: how do I wire a switched electrical receptacle?

I have double receptacle that has 3 wires coming in: one being the main power wire; one is incoming which feeds another receptacle, and the 3rd wire will feed a single pole switch. How do I wire the receptacle and then, how do I wire the single pole switch with 2 incoming wires? - JMS 6/3/12


JMS I don't have a perfectly clear idea of what you are wiring, but it may help to simplify: using a twist on connector and additional short wire lengths, the incoming hot and neutral can then be connected to receptacles in the same box, and any outgoing hot and neutral join the same twist on connectors.

Typically when I see a switch wired from a receptacle box the switch is being used to make one of the receptacles switchable while leaving the others always -on. in that case the electrician may run a 14-2 wire (hot, neutral, ground) from the receptacle box to the switch, putting black tape on the ends of the white wire to show that BOTH wires are actually carrying current. Those wires, back in the receptacle box, then interrupt power to the "switched" receptacle.

Question: what do I do with a third white wire attached to the side of the old receptacle when I'm moving them

I have changed several receptacles in my 1994 home, but this time when removing the receptacle from the wall I see a third white wire attached to the side of the old receptacle. Can you explain to me what this third neutral wire is? - DW 6/12/12


DW, it is just too dangerous to claim to know what wiring connections someone has made in a building that is unseen and untested.

It would be common for an additional white wire connected to an electrical receptacle to be carrying the neutral line to another receptacle downstream. In other words the incoming neutral is connected to one terminal and the outgoing neutral is connected to a second screw that is electrically common with the first.

Check for a second hot wire also present in the same box.

Question: what do I do with the screws to which no wire is connected on a conventional "plug" (wall receptacle)?

At the end of a circuit, I'm only using 2 of the 4 screws on a conventional plug. What should I do with the 2 unused screws? Should they be screwed all the way in? Or left partially unscrewed? Or does it matter? - Chris Rasko 7/8/12



regarding the un-used screw terminals on an electrical receptacle, you should simply screw them all the way in and leave them alone. Don't remove the screws - it's not necessary, they are deliberately hard to remove completely, and they could be needed in some future wiring change.

Question: can I add an electrical outlet on the wall where there is already a light switch?

I would like to wire in an outlet on the same wall where there is currently a light switch. Can I run wires from the light switch to power the outlet?The light switch is a 2 way switch. thank you. - Marv Walker 7/10/12



Well yes, maybe, sort-of.

Because a light switch is indeed switching a hot wire to the light, you've got power at the switch location. But depending on how the building is wired, you may not have an acceptable neutral wire, and in some still older circuits you may not have a safe ground wire.

Provided that you know how to work on electrical wiring without getting killed by electrocution, you (or your electrician) will open the switch box, carefully pull the switch assembly out enough to inspect for additional wires that may be present, and then use a VOM or DMM or even a simple neon tester to determine what wires are present.

To add a receptacle you need a proper hot, neutral and ground wire.

Watch out: if the "hot" wire in your light switch is on a 3-way circuit you may not always have power at your add-on receptacle.

Question: Wire Routing: armor around wire through concrete?

I am running a new 15A outlet into the back of a bookcase in a 50 year old house with updated electrical. The wire runs out the back of the retrofit box and down through the concrete foundation into the crawlspace to a wire I plan to splice into. Do I need to put armor around the wire run through the foundation? It goes through open air for about 2 feet and there is no way to secure it to anything.

Tom - 7/19/12


You need to look at the type and rating of the electrical wire to determine if it is permitted to bury it in concrete or not.

Question: Am I allowed to add one more outlet onto an existing string?

I have an existing outlet being used for lamps I wanna run one more outlet shares from the hot on is it okay? - PHantum 113 8/1/12



Usually, yes provided all safe and proper wiring code procedures are followed.
If the circuit is overloaded already, no.
If the circuit is knob and tube wiring, no - we don't extend knob and tube.

Question: I am trying to hook up two receptacles from a single line pair

I’m attempting to wire two separate receptacles from one (line) wire, not in-line one after the other but effectively as a “Y” from a junction box with two load lines out (one to a north wall receptacle and the other to a south wall receptacle in my barn).

Using screw-on connectors, I connected the three black wires together; the three white wires together; and the three green wires to a pigtail screwed into the junction box. One receptacle works fine, but plugging anything into the other receptacle trips the circuit breaker. If this is not the correct wiring configuration within the junction box, what is the solution? - Robert 8/9/12



I agree that you've got a miswired connection and it sounds like a short somewhere, but no way can nor should someone risk killing you by pretending we can see what you did. There are plenty of possible snafus, such as overtightening a wire clamp that cuts into and shorts a wire.

Reader follow-up:

Thanks DanJoeFriedman,
Turns out the over tightened wire clamp cutting into a wire was the problem.

Question: is it legal to convert a split receptacle into two separate receptacles

Is it legal to change a spit receptacle to two separate receptacles? - Gord



unless I've missed something, sure. You see this all the time. Instead of a single receptacle that has been split-wired to feed from two different circuits (usually using a common neutral and properly wired in the panel etc), you often see a 4" box with a pair of receptacles that side by side are run from different circuits instead of up and down different circuits in the same box.

Watch out about overloading the circuit however.

Question: I've lost electrical power to the whole room after testing power at the light switch

I've lost elec to the whole room.

I tested the wiring at the light switch.

If I turn the switch off I get elec to the switch,If I turn it on I get no the switch. I've lost electricity to the whole room - Dave


Dave, your wiring or perhaps the switch itself is unsafe; sounds as if it's shorted. Leave the circuit off until the wiring has been traced, lest you start a fire or zap someone.

Question: which way is "right side up" for electrical outlets - more views

One comment regarding 'inverted' outlet mounting (ground up, vs down).
While not specified in the code, I have noted that several electricians PREFER to mount a switched outlet so that the ground prong is up while mounting the non-switched outlets with the ground down. That way the homeowner can quickly determine a switched from a non-switched outlet. - Anon 9/5/12

Reply: secret codes are confusing


About upside down electrical outlets - thanks for the interesting comment. Unfortunately because there's no standard mount position associated with switched electrical receptacles, the next owner in a home will probably be confused unless the secret code is passed-on to everyone.

Question: converting 2-prong to 3-prong grounded electrical receptacles on a two-wire system

I'm changing out 2 prong receptacles to two prong + ground receptacles on a two wire system. The boxes are metal. Is it acceptable to screw a bare wire to the box with a self tapping screw and hook to the ground screw? Do I need to check to make sure the box is grounded, if so, what is the best method? - Ben 10/9/12


Watch out: no, what you propose is improper and unsafe even though it would "appear" to work. To add a grounding conductor or "ground wire" to a two-wire circuit you need to add a physical wire. The dangers of using the existing metal box and BX or armored cable for the ground path (I know that it's tempting) are several:

That path, which relies on numerous parts that can often be loose, is unreliable: the path is from the new grounded receptacle's internal grounding connector through a rivet to a metal strap on the body of the receptacle, through mounting screws through the receptacle's mounting ears, through a threaded hole in the metal receptacle box, through a metal BX connector which itself relies on at least four parts to be secured to the metal box, through a set screw from that connector into the armored cable, and through god knows how many more sets of these parts down the entire remainder of the electrical circuit.

That path also is not intended to carry current, and should it do so in an emergency, someone touching the BX exterior could be electrocuted.

Finally, the receptacle manufacturer provides a ground screw on the receptacle that is intended to be connected by copper wire to a ground wire, parts and codes being ignored if you try using the box and its wire as the ground path.

On an ungrounded electrical circuit you should install only two-prong, ungrounded receptacles - that is code compliant and that also lets users know that there is no reliable electrical ground present.

Question: are receptacles wired after a GFI receptacle OK?

Are receptacles wired after GFI receptacles OK? - Denny 11/25/12



Yes, and if wired correctly the downstream receptacles will also be GFCI protected.

Watch out: When wiring a GFCI the incoming leads are connected to the LINE terminals and the downstream receptacles are connected to the LOAD terminals marked on the back of the receptacle. If the devices is not wired correctly it is unsafe and does not provide the intended safety protection from ground faults.

Question: how do I wire multi-way light switches so that all switches can be "down" or "up" when the lights are all off.

How should multiple way light switches be wired so that when all switches are down/up the light is off? Only some of the two-way switches in the house are working that way. With the 3-way and 4-way there's always one switch that has to be opposite the others.
Thx, Jim


Jim this is one of my favorite questions - thanks. Because a circuit with two or more "three-way" switches installed can be turned on or off from any of the switches on the circuit, it is impossible to wire the circuit so that when the circuit is "OFF" all of the switches are in a predictable position, say "down" (which we like to use to mean "off").

Imagine that all the switches are "down" and the lights are off (which is a possible case). Someone turns the lights ON at switch #1.

When someone wants to turn that light OFF, IF and ONLY IF that very same switch (now in the "up" position) is used, then by definition they are going to be using some other switch (now in the "down" position). When that "other" switch is used to turn lights off, it was "down" and is now switched "up".

You can't get there from here on a conventional 120V 3 or 4 or n-way lighting circuit.

Question: 3 plugs on one of my walls went out

Ok from everything I can tell I'm having trouble with trouble with 3 plugs on my outer wall has went out. I've did the common thing checked my breakers they are fine. Must not I have 2 switches in this room one on each wall but they do nothing I feel somehow those switches are connected to those 3 plugs. I've pulled the covers off each plug and noticed the wires are secured. I've flipped the switches in many combos with something plugged in and they still don't work at all. What can I do to fix it. I wanna avoid calling a electrician if possible. - Josh DeBerry 12/11/12



Start by checking fuses or circuit breakers. If there is no tripped breaker or blown fuse, I suspect a damaged receptacle, wire, or wire connector. Your electrician will track dowh the location of the fault. But if you know which receptacles were all wired on a given circuit, and with power on at the electrical panel, using a receptacle tester you can check to see if any of the devices on the circuit have power.

\Since receptacles are most often wired in a daisy-chain or series circuit, the last one that has power tells you that the problem is between that receptacle and the next one in the chain.

Question: I need to add a light, fan, and fan switch to an existing bath - I can't find where to kill the power

very informative article thumbs up . I have a question Tough
I am renovating a customers bathroom and need to install another light as well as a fan witch requires a larger box to be installed in the wall. when i checked the existing switch there was a black and a white wire on the switch and when i attempted to shut the power off to the light and switch at the panel there is no breaker that kills the power to the light what is the likely cause of this and how do i fix this problem - Blinden 12/12/12



It would be odd for a bath light circuit to be wired with no over current protection, and very dangerous too. Try each breaker in the panel in turn to find the one controlling the circuit.

As the switch is interrupting only the hot wire it is common practice to run a standard 2-wire line from the light to the switch. In meticulous electrical work the installer would wrap black tape near the ends of the white wire to indicate that in this use it is a hot lead not a neutral wire.

Depending on the light location, such as near a shower, it may need GFCI protection as well.


I have one line with power coming into a box that will have one two way switch, one three way switch and one power line exiting. Is it proper to splice the incoming black wire to make 3 black wires by pig tailing with wire connectors and doing the same for the white wire and ground? - is it ok? 12/13/12


I'm sorry but I'm confused by the question. I think it's safe to say that in general it's common practice to use a twist-on connector to splice pigtails or individual wires at an individual hot or neutral wire where more connections are needed than fit with the original wire.

Just watch out to avoid violating the space or number of connectors permitted in a junction box of the particular size you're working on.

Question: comment

Electrical wiring are the devices that are used to generate electricity. There are different types of electrical wiring that are usually vary according to three factors - purpose, quantity of electricity to be carried, and location. All the above three factors are really very important while doing electrical wiring. - Bella Cruse, Dublin electrical contractor


Thanks Bella.

Question: Light Wiring: which circuit is better to use when adding a closet light

If I want to add light to closet, which circuit is it better to pull from? I have access to 120 plug and switches in outside wall facing away from closet that could be pulled into closet. Also, can you help explain the two different wiring configurations on my non GFI plugs. On two different plugs on different walls the plugs are 8 wire push in style (4 hot and 4 common), but the wiring configuration is different between the two plugs. One one all white and black are inserted in the bottom 4 connectors with tabs in place. On another same style plug, one set of 4 wires (2 black and 2 white) are inserted in bottom left row, and other set of 4 wires are inserted in opposite side top row. These plugs are not controlled by switches. Thank you. - Chris 12/30/12



In my OPINION, it's best to connect a closet light to the room lighting circuit if possible.

About your other question, I'm a little confused by the query, but in general, receptacles and switches often have more than one permitted connection point, such as under a screw terminal, on older devices via a back-wiring push-in connector (something we do not recommend using), or on newer devices a side-clamp operated by a screw.

In all events, regardless of which connection point you are using, receptacles and switches have a designated side or screw or connector set for the white (neutral wire) (typically the side that has a silver colored screw and that is marked NEUTRAL on the device) and for the black (hot wire) (typically the side that has a brass-colored screwed and is marked LINE or HOT or BLACKI).

Question: I'm installing a box extension but the top screw won't hold - it's stripped

I started installing a box-extender on a receptacle in my kitchen because I'm tiling my backsplash and need to raise the outlet above the tile. However, the top screw connecting the outlet and box wouldn't hold. I spent way too much time bent double under my cabinets trying to get it to bite, but when I finally gave up and pulled it out it was stripped at the tip (which was as far as it'd go in). I'm sorry to bother you with triviality, but I'm new to home renos and don't know what to do. Advice? - Julia 1/29/13

Reply: step by step tips for replacing a stripped electrical receptacle or switch box mounting screw or screw opening


If the problem is the screw itself is stripped, simply purchase a replacement screw or a hand full of them from your electrical supplier. These screws are a standard thread and length, but longer versions are available at any hardware store.

For the case you describe, if the stripped problem is the mounting hole you'll need to either enlarge and tap the hole for the next size larger screw, or purchase a clip-on adapter that slips over the stripped ear through which the original hole passed.

Taking care to move electrical wires out of the way of your drill bit, in a metal electrical box you can drill out the 6/32 screw opening to tap and accept an 8/32 screw.

For photos and step by step details on how to repair stripped electrical outlet mounting screws, see OUTLET BOX SCREW REPAIR.

Question: can I connect an outlet using the hot wire going in and out

(May 6, 2014) Anonymous said:
can I hoof up an outlet using the hot wire coming in and going out


Anon, in the More Reading links just above, click the article titled

CONNECTION DETAILS - where to connect black, white, red, green, ground wires

and read about LINE and LOAD connection terminals on the receptacle for an illustrated example of hooking up outlets in series.

Question: I want to add a light outside tappped off a receptacle

(June 19, 2014) Anonymous said:
I want to add a light outside , instead of running power all the way from the breaker box. . Can I run a wire from end of the line receptical. If I ca how? I don't want to turn the outlets off


Anon, for someone who appears not to be a trained electrician I can't agree to recommend any electrical wiring procedure adding an electrical receptacle using the approach such as you describe working on live wires. The risks include fire, shock, electrocution, death.

Question: why so many wires in one standard outlet box?

(July 6, 2014) Troy said:
I just changed one of my outlets in my house and was confused at why there were so many wires in one standard outlet. There was the ground, white and black as normal but the second screw for black has 2 wires and the back of he outlet had an additional white and black in the respective holes in the back of the outlet. I am assuming that this was intended to be hooked up to a switch someplace, but it wasn't and it works.



An electrical receptacle is most often wire in series with others in the circuit.
So there will be

Hot in
Neutral in
Ground in
Connected to terminals on the receptacle

Hot out
Neutral out
Ground out
connected to additonal terminals on the terminal.

If the receptacle is switched (by a wall switch for example) two more wires are used to interrupt the black or hot wire to the device.

Question: routing wiring in a garage

8/15/15 Garrett said:

Hi, I am curious if while running garage electrical wiring, you can, or can not, run the wire from the electrical Outlet, DOWN the stud, across, then Back Up to the next Outlet. Versus Running your wire from the Electrical Outlet, UP the Stud, across, then Down again.... IS there a reference? is running it Upwards, versus Downwards (and it would be about 1 foot OFF/From the Cement Floor). If that is understandable? THANKS!!

The main reason, I would want to do it like this is that I wouldn't need to be climbing/moving a ladder every few feet. :)


Garrett you could run wire up and down the center of studs (in the wall cavity) as long as it's protected where necesary; Wire has to be secured and protected as required but codes don't specify direction to run wires.

Question: outlets in parallel

(Sept 5, 2014) arianne said:
how will i install convenience outlet in parallel connection? thanks



Question: ground opening up or down on receptacles?

(Sept 11, 2014) dave a. said:
I'm installing grounded outlets. I notice most outlets are mounted in their boxes with the middle ground opening on the bottom of the outlet but is that required? I would like to orient the outlets so that the ground opening is on top; I think it's easier to plug in grounded appliances that way.


There are endless arguments, Dave about which way receptacles should face, and the net teems with opinions and theories about which more securely hold the wall plug in place, but not code not law. You can flip'em if you want.

Question: my wall plug is burning - what should I do

(Nov 10, 2014) annie said:
i have 4 wires instead of 5 going to my wall plug which is causing it to burn...there should be two positive and two negative and one ground..instead i have two positive and one negative and one ground. what should i do



You describe an unsafe condition, a fire and shock and death hazard. Turn OFF the circuit immediately at the electrical panel. Then it's time to call a licensed electrician.

Question: receptacles on a lighting circuit

Jan 4, 2015) Anonymous said:
We have outdoor plug outlets connected to lights circuit breaker. Is this legal?


Sounds like expedient wiring or wiring done without code inspections and a permit.

Question: half of the outlet doesn't work

(Mar 12, 2015) bob said:
I discovered that the top outlet works but not the bottom outlet. what could cause this? what do I need to do.



A damaged or broken connection in the receptacle itself, or if the bottom receptacle opening was split-wired to be powered by a different circuit, that circuit may have an open wire or a tripped breaker or fuse - OR - it may have been wired to a light switch in the room.


(Apr 21, 2015) paul said:
how do i connect the two wires of a plug to a ceiling fan. does it make a difference which is connected to the hot wire?


(Apr 21, 2015) Opinionator said:
Black to black, white to white.

Question: arcing when I started loosening an electrical outlet

(May 2, 2015) lonnie said:
We painted a room and we wanted to change out the 3 old receptacles from brown to white.I did the first 2 with know problem. When I started to loosing the screw on the 3rd one it starting arcing so I stop. I have changed out several over the years and never had one to arc like this one.I went out side to see if the breaker trip and it did not.



First, it would be safer, common sense, and might save a life to turn off power before working on electrical equipment.

Second, it's possible that some shorts don't trip a breaker but the description is worrisome. What is the brand and age of the circuit breakers and panel installed? Some brands are particularly prone to unsafe No-trip problems. You're risking a house fire as well as shock hazards.

Question: replacing worn AC wall outlets

(May 25, 2015) Rob said:
I am replacing some worn ac wall outlets, for a friend. I have already, successfully replaced two others. On this one, it tests, correctly, with a plug-in AC tester, when the outlet is just connected, but, not yet inserted into the enclosure box. But, every time I push it in and secure it, it shorts and throws the breaker, as soon as the breaker is turned on. I do not believe any of the connections are protruding out from the screw lugs. Where could this short be occurring ? I have a multi-meter, also; just don't see where it could be shorting.


Sounds like an overcrowded electrical box is bending and damaging connections when you push the receptacle back into the box - an unsafe condition risking fire or shock. You need to use a larger box if that's the trouble. Turn off power to the circuit.

(May 25, 2015) Rob said:
Thank you for the quick reply. To clarify, I do have the breaker turned off, during installation. As soon as I complete the hook-up, I am restoring the breaker, with a plug-in tester, inserted. The power comes on, and the tester indicates power, with correct polarity and ground. I am turning the breaker off, before pushing the receptacle back into the enclosure box. But, when I turn the breaker back, on, after the receptacle is secured in the enclosure, that is when there is a pop, coming from inside the enclosure, and the breaker pops. I am an electronic technician, but, not an electrician. I guess I am just asking for a second opinion, from mine. I am thinking that the supply wires might have an exposed surface, and might be shorting, when pushed together in the enclosure box. I did not see evidence of an exposed area, but, I do not see what else it could be, maybe need to inspect, more closely. Agree ?

Question: DIY wiring troubles

(Aug 13, 2015) Brad said:
I have a 50 amp breaker in the main house breaker box. I've run wire to a sub-breaker with a 15 amp breaker. Can I run wire from the 15 amp breaker to a to a grounded outlet for 120 volt power use? With an electrical tester, the digital readout was about 5V? Shouldn't it be about 120 V?


All due respect, Brad, what you describes sounds like damaged or improper electrical wiring, an unsafe condition that risks fire or death by electrocution. It's time to call a licensed electrician to track down what sounds like a voltage leak and dangerous conditions. Meanwhile leave that circuit OFF.

Question: can I connect the green screw to the white wire?

(Sept 29, 2015) john said:
if do not work with ground connected to green screw can I connect it to the white wire

Reply: No.

John your wiring suggestion is unsafe and improper. The green screw is for the grounding conductor and is not designed to carry current in normal operation. Therefore if your "plug" (wall receptacle) is not working, the green screw and ground wire are not the problem.

Never connect the ground (bare or green wire) to the neutral (white) or hot (black) wire: doing so can start a fire or kill someone.

Question: Can I use your wiring tips for sockets we usue in the E.U. ?

2015/10/22 Mark said:
Thank you for so detail tips. Especially pictures made me understand everything the most. I'm a memeber of EU and as you know I have another kind of sockets. Can I use your tutorials if i want to install european kind of sockets such as Obo?

OBO is een Duitse producent van systemen voor gebouwinstallatie zoals verbindings- en bevestigingssystemen, inbouwapparatuursystemen, kabel- en wandgoten, brand- en bliksembeveiliging en meer. OBO is een familiebedrijf dat in 1911 werd opgericht als stansfabriek voor bevestigingstechniek, en wordt inmiddels geleid door de vierde generatie Bettermann. Het bedrijf is in meer dan zestig landen actief. De vele producten van OBO worden gebruikt in bijvoorbeeld de scheepsbouw en voedingsmiddelenindustrie. Ook worden OBO-producten onder meer toegepast in zonne-energie-installaties, energiecentrales en tunnelbouw.


Generally, yes, Mark; but take a look at the different wire colour codes used in the E.U.


Article series contents


Continue reading at ELECTRICAL OUTLET, HOW TO ADD & WIRE or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.


Suggested citation for this web page

ELECTRICAL OUTLET WIRING FAQs at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia


Frequently Asked Questions (FAQs)

Click to Show or Hide FAQs

Ask a Question or Search InspectApedia

Questions & answers or comments about how to install and wire electrical outlets or receptacles in buildings.

Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

Search the InspectApedia website

Comment Box is loading comments...

Technical Reviewers & References

Click to Show or Hide Citations & References

Publisher's Google+ Page by Daniel Friedman