Electrical Outlet wire connections (C) D FriedmanElectrical Outlet Installation Wiring Procedures & Codes
How to wire an electrical receptacle, wall plug outlet: complete installation details

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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.

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Electrical Outlet Wiring Instructions for Homeowners & DIY Repairs

Electrical Outlet wire connections (C) D FriedmanOur photo (left) shows the black or "hot" wire connected to the brass-colored screw on an electrical receptacle.

Our photo at page top illustrates other wire connections shown out of the electrical box and thus is not an example of a proper electrical outlet installation.

Article series contents

How to add an electrical outlet in a home - i.e. an electrical receptacle

We use the proper term electrical receptacle to describe the "wall plug" or "wall outlet" into which you will insert a two-prong or three prong plug to connect an appliance, lamp, etc. Technically in the electrical code, an "outlet" is any place in where you provide a junction box and electrical wires to which something can be connected: a light fixture or an electrical receptacle, for example.

With a few simple tools, electrical wiring of an electrical receptacle is not difficult, but there are a few details to get right in order for the electrical receptacle to be safely installed.

Why might we need to add an electrical receptacle in a building?

  • Convenience: we'd like to be able to plug in more electrical devices at some spot, say at a home office;
  • Safety: we need to plug in more devices at some location and we don't want to risk tripping someone or starting a fire by using extension cords;
  • Function: we need to plug in more devices at some location in a building, or we need to plug in a new high-current using device in a building, and we find we keep blowing fuses or tripping a circuit breaker; in this case we want to add a whole new circuit, from electrical panel to the location where we need the outlet, so that we can deliver adequate electrical power without blowing fuses or tripping circuit breakers.

Electrical Outlet wire connections (C) D FriedmanWe summarize the electrical connections for wiring up a receptacle just below. Wiring details for electrical "outlets" properly called electrical receptacles, are at CONNECTION DETAILS.

On a conventional 120-volt "two pronged" electrical outlet that accepts grounded plugs (two prongs plus the rounded center ground connector prong), your circuit will have three wires:

  • The white "neutral" wire - this wire is connected to the silver screw on the electrical receptacle, often labeled "neutral" . You can see our white neutral wire connected to a silver screw on the receptacle in our photo, below-left.
  • The black "hot" wire - this wire is fed from the circuit breaker to deliver power to the receptacle, and it connects to the brass or bronze-colored screw on the receptacle, often labeled "hot" or "live".

    You will see the hot black wire connected to the bronze or darker-colored screw on the receptacle shown at below right. The receptacle we used for these photos happens to be a 20-A rated device that permits the wire to be inserted straight into a clamp that is tightened against the wire by the screw.
  • The bare ground wire - this wire connects to the green ground screw usually found on the bottom of the electrical receptacle (photo at left). You can also see our ground wire connected at the left side of our previous photo, above-left.

Reader 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.

Reader Question: how to wire up two different circuit-powered receptacles in one electrical box

Quad plex electrical receptacle wiring (C) Daniel FriedmanI would like to wire 2 single plugins to one live wire..how do i do that? - Channing


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

If your two plugins (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 FriedmanIf 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.

Because electricians often pull a multiwire circuit where they plan to split receptacle circuits within an individual electrical box while sharing a neutral wire, be sure to ake a look at multi-wire branch circuit wiring information and hook-up details

Reader Question: Which end of electrical outlets go "up"? The ground hole should be up, down, or sideways?

Electrical outlet with ground connector down (C) Daniel Friedman Electrical outlet with ground connector down (C) Daniel Friedman

Can the outlet be installed any way? For example ground hole facing up, down, or sideways? thanks, - Anon


Anon, the position of installation of an electrical outlet won't affect its operation and should not normally affect its approval by the electrical inspector.

In some areas I see the outlet installed with the ground connector always "up" as in our photo at left, though to me that's less attractive than the position shown in our electrical outlet photo at far left.

I've also seen arguments expressing the OPINION that the position of the grounding pin connector might help resist the tendency of a plug to fall out of its connection. That's nonsense. If a plug is falling out of a receptacle, one of the two objects is worn or damaged and should be replaced to assure a safe, mechanically secure connection.

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

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.


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

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.

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




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