Plastic electrical box (C) D Friedman Electrical Box Types & Sizes for Receptacles
How to choose the proper type of electrical box when wiring electrical receptacles (wall plugs or "outlets")

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

Guide to types of electrical receptacles (wall "outlets" or "wall plugs"):

How to choose the right type of electrical receptacle when adding or replacing a wall outlet in a building. Here we describe matching 15-Amp receptacles to 15-Amp circuits, 20-Amp receptacles to 20-Amp circuits, two-wire receptacles where no ground is present, GFCI and AFCI electrical receptacles, and the proper electrical box to hold and mount these devices.

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.

Green links show where you are. © Copyright 2015 InspectApedia.com, All Rights Reserved.

Choose the Proper Electrical Junction Box When Adding a Receptacle

Arcing in an under-sized electrical box (C) Carson Dunlop Associates

Article Contents

Table of Electrical Box Sizes vs Number of Wires Allowed

NEC Table 314.16 (A) Metal Electrical Boxes for Devices
Box Dimensions (Inches)
& Trade Name
Minimum Cu. In. Max # Conductors AWG 14 Max # Conductors AWG 12
3 x 2 x 1 1/2" Device Box 7.5 cu. in. 3 3
3 x 2 x 2 " Device Box 10 5 4
3 x 2 x 2 1/2" Device Box 12.5 6 5
3 x 2 x 3 1/2" Device Box 18 9 8
4 x 2 1/2 x 1 1/2" Device Box 10.3 5 4
4 x 2 1/2 x 1 7/8" Device Box 13 6 5
4 x 2 1/2 x 2 1/8" Device Box 18 7 6
4 x 1 1/4" square 18 9 8
4 x 2 1/4" square 21 10 9
4 x 2 1/4" square 30.3 15 13
Notes: The National Electrical Code Article 314 contains complete details and tables of electrical box sizes in dimensions and cubic inches and should be consulted for complete accuracy because the actual size of the box required, in cubic inches, depends on the number of wires that will be within that enclosure. This is an excerpt pertinent to wiring electrical receptacles and switches; other wire sized and applications are given in the source NEC.
NEC 314.16(B) Electrical Box Volume Required Per Conductor (wire)
Conductor size (wire size) Free space within the box for each conductor
No. 14 2 cubic inches
No. 12 2.25 cubic inches
No. 10 2.5 cubic inches
Notes: This is an excerpt pertinent to wiring electrical receptacles and switches; other wire sized and applications are given in the source NEC.

Typical Electrical Boxes for Single Receptacles, Switches, or Splices

Typical electrical junction boxes used for receptacle installation to accommodates a single receptacle are 2" x 4" metal or plastic boxes of varying depth. Choose a deeper box if you have more than the minimum number of wires entering & leaving the box or it will be over-crowded and may violate building electrical codes.

Below are an older style steel electrical boxes nailed to wood framing in a building. The box is carrying six wires in total: two "hot", two neutral, and two grounds.

Metal electrical box in new work installation, nailed to wood framing (C) Daniel Friedman Small steel electrical box with aluminum wiring (C) Daniel Friedman

At above right in addition to aluminum wiring hazards the box is overcrowded.
See ALUMINUM WIRE REPAIR SPLICE SPACE.
Also
See ALUMINUM WIRING HAZARDS & REPAIRS.

It's likely to be permitted and safe to install a larger sized junction box than you need for an outlet or switch or wire splice, but you may need to purchase a special adapter-cover for the box in order to properly secure an electrical outlet therein. Installing a junction box that is too small is illegal and unsafe.

Typical 4-inch Electrical Boxes used for Single (or more often) Duplex Electrical Receptacles

Below-left we show a typical 4-inch metal junction box, and below-right a common and deeper plastic junction box.

Metal electrical box (C) D Friedman Plastic electrical box (C) D Friedman

Electrical junction boxes are required for all wall plugs ?

Burned up electrical receptacle (C) Daniel FriedmanReader Question: Do I really need an electrical box to put a new wall plug in ? - Thomas

Reply:

Yes, Thomas, electrical devices such as switches and receptacles (wall plugs) need to be mounted in a code-approved plastic or metal receptacle (box) for fire safety as well as to assure that the device is mechanically secure.

In fact when you purchase a "wall plug" you'll see that its metal mounting ears and screws are spaced and designed to connect to an electrical box.

Watch out: while it's physically possible to install a wall receptacle or "plug" without using an enclosure, doing so is dangerous, risking fire and shock, and of course, it's also illegal in virtually every building code jurisdiction.

Take a look at our photograph at left - a fire was contained within this electrical junction box. Had the box been omitted there is a good chance the fire would have spread to the building itself.

When we hear a question like this it makes me very afraid for you and for future building occupants - as amateur electrical wiring is dangerous.

Details about how to wire up an electrical receptacle are at ELECTRICAL RECEPTACLE CONNECTION DETAILS - where to connect black, white, red, green, ground wire.

Gang Boxes - built-up electrical boxes for more space

Ghomas & Betts Steel City Brand steel gang box sketch (C) Daniel FriedmanGang boxes are steel electrical boxes with removable sides and screw fittings that permit multiple metal boxes to be joined together to obtain more space. As we discuss at ALUMINUM WIRE REPAIR SPLICE SPACE, Some electrical boxes installed as original work are stamped out of a single piece of steel and cannot be expanded. Others called "gangable" metallic boxes such as by (Thomas & Betts - Steel City Brand) installed as original work included side plates that could be removed to install a sidecar extension.

Gangable electrical boxes can be expanded by adding another box along the open (away from the stud or joist) side of the existing box (requiring a larger wall opening), or by adding a "side car" extension that hides behind the wall surface.

Sketch at left: illustrates the removable side-plates on a gang-type electrical box. Boxes of this type can be expanded along their open side - the side that has not been already fastened to a stud or joist.

To add an electrical box extension you must have access to the top or bottom screw on the open side of the box to remove the side plate - that's where you'd add on a second gangable box as an extension or a side-car hidden box extension.

Watch out: it will be almost impossible to extend an original-work metallic box size using an extension without cutting open and thus damaging the wall at one side of the box. However in my OPINION drywall repairs are trivial compared with the cost of complete re-wiring with all copper in a building with aluminum wired branch circuits.

Gang Box Extenders for More Wiring Space

In addition to screwing multiple gang boxes together to construct a large "new work" electrical installation, gang boxes can be extended behind the wall to obtain a small amount of additional wiring space: illustrated below.

Steel gang box with hardware for old work installation (C) Daniel Friedman Gang box extender in position but not installed (C) Daniel Friedman

At above left is a single "gang box" steel electrical box. At above right I've removed the left side of the gang box and I have installed a steel
"side car" or "box extender" (yellow arrow in the photo below) to increase the cubic inches of wiring space in this electrical box. These box extenders can be used to add a small amount of wiring space that can bring an otherwise too-small gang box up to code without having to cut a larger opening in the building wall.

Gang box with side car extension (C) Daniel Friedman GFCI jammed into a gang box with sidecar box extender (C) Daniel Friedman

You'll notice that the box extender is shaped to be recessed to slip behind the thickness of the plaster or drywall. At below right we see a modern GFCI electrical receptacle shoehorned into a too-small gang-box that has been extended with a box extender or "sidecar" in order to try to include AlumiConn™ aluminum-to-copper pigtailing connectors.
See ALUMINUM WIRE REPAIR SPLICE SPACE where we discuss all of the approaches to obtaining more wiring or device space in electrical boxes.

Where wall depth permits, a better approach where more wiring space is needed is to remove the existing electrical box and install a deeper box in the same opening.

Electrical box extensions & supplies for more wiring space or increased cubic inches of electrical box space

New Work Compared with Old Work Electrical Boxes - Old Workboxes

New Work Electrical Box Examples

Normally a "new work" plastic electrical box installed during new construction is either nailed to the building framing (shown below) or if it needs to be spaced away from a stud or joist in a wall or ceiling it may be supported by a bracket that is in turn nailed to the building framing.
See ELECTRICAL JUNCTION BOX TYPES.

Plastic electrical box nailed to wall stud in new construction (C) Daniel Friedman Plastic electrical box installed for ceiling light (C) Daniel Friedman

Examples of Old Work Electrical Boxes & Methods of Installation

When an electrical circuit and electrical boxes are being added to an existing structure wires are snaked through building cavities to the desired fixture location and an old-work electrical box or "junction box" is installed to contain electrical splices and devices. Both metal and plastic old-work electrical boxes are available and there is a variety of clips, clamps, and other devices used to secure electrical boxes in a wall or ceiling when the box cannot be conveniently nailed or screwed directly to the structure.

Steel gang box with hardware for old work installation (C) Daniel Friedman Clips used to secure an old work metal electrical box (C) Daniel Friedman

[Click to enlarge any image]

At above left is a steel gang box with mounting hardware to permit old-work installation: those metal brackets at the top and bottom of the box can be screwed to a wall surface. In my opinion I'd prefer to see this box used in a wood or paneled wall or on a plaster wall on wood lath rather than on simple drywall as I worry that in a receptacle installation someone may find they pull the whole installation off of the drywall when removing a wall plug.

At above right we illustrate thin steel clips (colored orange) that have been used (with considerable care) to secure a steel gang box in a drywall or plaster wall (adapted from Steel City products). Adding these clips can make the box far more secure in the wall than if we only use the brackets shown in the left and center illustrations.

Plastic electrical box (C) Daniel Friedman Plastic old work electrical box (C) Daniel Friedman Carlon old workbox, round, 18 cubic inch blue plastic with metalground connector (C) Daniel Friedman

At above left and center are two rectangular old-work switch or receptacle boxes. At above left is a Carlon 25 cubic inch 2-gang plastic electrical box.

At above center is an old-work plastic Zip Box suitable for a single electrical switch or receptacle. The blue ear shown at the electrical Zip Box top at right (orange arrow) is pulled against the interior surface of the wall plaster or drywall as the installation screw (green arrow) is turned.

At above right, using a Carlon round 81 cubic-inch oldwork box as an example, we show the mounting screws that cause the swing-clamps to open and then pinch the box against plaster or drywall through which the box has been mounted (red arrows).

The purple circle and smaller oval show us where the device-mounting screws (receptacle, switch, light-weight lamp fixture bracket) will be secured. You can see that the three swing-clamps for this oldwork box are in the open position but they'd be moved to a closed position to insert the box through a round opening cut in drywall or plaster.

Watch out: As we discuss at PLASTIC ELECTRICAL BOX REPAIR, the round blue Carlon electrical box at above right includes a metal grounding lug shown in our larger purple circle. This Carlon # B618RP-UPC is a 4 1/4" diameter electrical box that has a UL 514C listing, meets NEMA OS-2, and is specifically indicated by the manufacturer as not for fixture support in the ceiling. That PLASTIC ELECTRICAL BOX REPAIR article illustrates a failure where this box was used to hang a ceiling light fixture. The light began to fall out of the ceiling.

Below is another old-work plastic electrical box being installed in a ceiling.

Installing an old-work electrical box in an existing ceiling (C) Daniel Friedman Old work electrical box being inserted into the ceiling (C) Daniel Friedman

Shown above, the rotating swing-clamps on the plastic old work box are open for illustration (yellow arrow, photo at above left).

The swing clamps are pressed flat against the box sides (red arrow at above right) as it is pushed through its mounting hole into the ceiling or wall cavity. As the box mounting screws (green arrow) are turned the plastic ears rotate open and then are pulled tight against the drywall or plaster ceiling or wall surfaces, pulling the old work electrical box flange against the exposed side of the ceiling or wall and holding it in place.

In new construction an old-work box may be also needed if the electrician is asked to leave a wire exposed for future installation of fixture whose precise location has not been determined. In this case she may leave the wire protruding through a ceiling or wall and may plan on later re-locating the wire precisely using an old work retrofit type electrical box.
See PLASTIC ELECTRICAL BOX REPAIR for an example of selecting and installing an old work electrical box to power a ceiling-mounted light fixture

Watch out: do not rely on old work boxes with minimal support (just drywall, for example) to carry heavier fixtures or ones subject to vibration or movement such as a ceiling fan. Such installations are unsafe.

Reader Question: When adding an electrical outlet in a garage, what's code: metal or plastic junction box?

I am putting outlet in garage wall that has kitchen on the other side. What is code, plastic or metal? I would think in a garage fire that a plastic box would melt and fire would go through the wall faster? - Steve Smith

Reply:

Steve both plastic and metal receptacle boxes are code-approved and neither, properly installed and wired, should violate the fire-rating of the wall.

Reader Question: how do I increase the projection of outlets into a room so I can add a kitchen backsplash

Gang Box Extender Electrical Box Extension from Arlington IndustriesI am unable to find instructions on how to increase the projection into the room of existing electrical outlets so that I can tile the kitchen backsplash and have the outlets be at the appropriate depth for use and safety. Do I move forward the box to which the outlet is screwed and if so how? - Anne 3/22/12

Reply: use electrical box extenders - shop for an "electrical box extension" of the proper thickness

Anne,

Building suppliers like Home Depot and also your electrical supply house sell "box extenders" in varying thicknesses, made of plastic, code approved, for the purpose you describe. The electrical box extender is sized and shaped to match the electrical receptacle box to which it is to fit.

By removing the electrical receptacle from its mount on the existing box, the box extender is fit as a sort of large rectangular plastic washer, mounting between the existing box edge or surface and the mounting ears of the receptacle or switch.

Electrical box extensions are sold in plastic and steel and in thicknesses from about 1/8" up to an inch or even more. The plastic electrical "gang box extension" shown at above left is produced by Arlington Industries but there are several manufacturers. Just choose an electrical box extender that brings your receptacles far enough forward to suit the thickness of the kitchen backsplash or tile.

Watch out: don't try a makeshift substitute using washers or junk - that's an improper and unsafe repair, leaving a gap around the electrical box sides.

Reader Comments:

Anne,
I'm in the midst of a remodel that posed the same 'problem'. Work box extender rings are available at Home Depot and Lowes in the electrical department. They are plastic, color-coded frames that fit between the front edge of the box and the outlet/switch. The screws that secure the outlet/switch to the box also secure the frame in place. The frames are available in multiple thicknesses. I suggest you take a tile sample with you so that you can get the correct thickness for your project. Depending on the thickness of the tile, you may need to combine two frames of different thicknesses.

While I was changing a failed plug I noticed that the box was too deep. I looked into extenders, and plastic ones (Arlington BE1) are less expensive. Are CSA approved plastic box extenders code compliant for homes? - Gary 7/19/12

Question: how many electrical receptacles are allowed on a 20-amp circuit? How many receptacles on a 15-amp circuit?

How many receptacles can be wired To one 20 amp circuit No. 12. Wire - John K.

Reply: 10 electrical receptacles to be wired on a 15-Amp (#14 copper) wire circuit

20 Amp electrical outlet (C) D FriedmanJohn K:

Our photo (left) shows a 20-Amp electrical receptacle - you can recognize it by that horizontal opening that makes the left-hand slot look like the letter "T" on its side.

In general, the Electrical Code [NEC] allows

Our photo (left) illustrates an electrical receptacle intended for use on a 20-Amp circuit.

Notice that extra horizontal slot? You won't see that on a 15-Amp electrical receptacle.

Reader 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

Reply: minimum heights for electrical receptacles is not specified in the electrical code NEC

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.

See HEIGHT above FLOOR for OUTLETS for details.

Question: are electrical junction boxes required for wall plugs?

Burned up electrical receptacle (C) Daniel FriedmanDo I really need an electrical box to put a new wall plug in ? - Thomas

Reply:

Yes, Thomas, electrical devices such as switches and receptacles (wall plugs) need to be mounted in a code-approved plastic or metal receptacle (box) for fire safety as well as to assure that the device is mechanically secure. In fact when you purchase a "wall plug" you'll see that its metal mounting ears and screws are spaced and designed to connect to an electrical box.

Watch out: while it's physically possible to install a wall receptacle or "plug" without using an enclosure, doing so is dangerous, risking fire and shock, and of course, it's also illegal in virtually every building code jurisdiction.

Take a look at our photograph at left - a fire was contained within this electrical junction box. Had the box been omitted there is a good chance the fire would have spread to the building itself.

When we hear a question like this it makes me very afraid for you and for future building occupants - as amateur electrical wiring is dangerous.

 

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

Reply:

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.

Question: When adding an electrical outlet in a garage, what's code: metal or plastic junction box?

I am putting outlet in garage wall that has kitchen on the other side. What is code, plastic or metal? I would think in a garage fire that a plastic box would melt and fire would go through the wall faster? - Steve Smith

Reply:

Steve both plastic and metal receptacle boxes are code-approved and neither, properly installed and wired, should violate the fire-rating of the wall.

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.

Reply:

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.

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.

Question: how many electrical receptacles are allowed on a 20-amp circuit? How many receptacles on a 15-amp circuit?

How many receptacles can be wired To one 20 amp circuit No. 12. Wire - John K.

Reply:

20 Amp electrical outlet (C) D FriedmanJohn K:

Our photo (left) shows a 20-Amp electrical receptacle - you can recognize it by that horizontal opening that makes the left-hand slot look like the letter "T" on its side.

In general, the Electrical Code [NEC] allows

Our photo (left) illustrates an electrical receptacle intended for use on a 20-Amp circuit.

Notice that extra horizontal slot? You won't see that on a 15-Amp electrical receptacle.

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

Reply:

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: how do I increase the projection of outlets into a room so I can add a kitchen backsplash

Gang Box Extender Electrical Box Extension from Arlington IndustriesI am unable to find instructions on how to increase the projection into the room of existing electrical outlets so that I can tile the kitchen backsplash and have the outlets be at the appropriate depth for use and safety. Do I move forward the box to which the outlet is screwed and if so how? - Anne 3/22/12

Reply: use electrical box extenders - shop for an "electrical box extension" of the proper thickness

Anne,

Building suppliers like Home Depot and also your electrical supply house sell "box extenders" in varying thicknesses, made of plastic, code approved, for the purpose you describe. The electrical box extender is sized and shaped to match the electrical receptacle box to which it is to fit. By removing the electrical receptacle from its mount on the existing box, the box extender is fit as a sort of large rectangular plastic washer, mounting between the existing box edge or surface and the mounting ears of the receptacle or switch.

Electrical box extensions are sold in plastic and steel and in thicknesses from about 1/8" up to an inch or even more. The plastic electrical "gang box extension" shown at above left is produced by Arlington Industries but there are several manufacturers. Just choose an electrical box extender that brings your receptacles far enough forward to suit the thickness of the kitchen backsplash or tile.

Watch out: don't try a makeshift substitute using washers or junk - that's an improper and unsafe repair, leaving a gap around the electrical box sides.

Reader Comments:

Anne,
I'm in the midst of a remodel that posed the same 'problem'. Work box extender rings are available at Home Depot and Lowes in the electrical department. They are plastic, color-coded frames that fit between the front edge of the box and the outlet/switch. The screws that secure the outlet/switch to the box also secure the frame in place. The frames are available in multiple thicknesses. I suggest you take a tile sample with you so that you can get the correct thickness for your project. Depending on the thickness of the tile, you may need to combine two frames of different thicknesses.

While I was changing a failed plug I noticed that the box was too deep. I looked into extenders, and plastic ones (Arlington BE1) are less expensive. Are CSA approved plastic box extenders code compliant for homes? - Gary 7/19/12

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

Reply:

Jerm, in the article above at HEIGHT above FLOOR for OUTLETS we give the data you want. Let me know if anything is unclear.

Question:

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

Reply:

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.

...


Continue reading at LOCATIONS for ELECTRICAL RECEPTACLES or select a topic from the More Reading links or topic ARTICLE INDEX shown below.

Or see PLASTIC ELECTRICAL BOX REPAIR

Or see ELECTRICAL BOX SCREW REPAIR

Or see SIZE of WIRE REQUIRED for receptacle circuits and similar wiring situations

Or see TYPES of ELECTRICAL RECEPTACLES

Suggested citation for this web page

ELECTRICAL JUNCTION BOX TYPES at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

More Reading

Green link shows where you are in this article series.

INDEX to RELATED ARTICLES: ARTICLE INDEX to ELECTRICAL INSPECTION & TESTING

OR use the Search Box found below at 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

HTML Comment Box is loading comments...

Technical Reviewers & References

Publisher's Google+ Page by Daniel Friedman

Click to Show or Hide Citations & References

Support InspectApedia.com & See Fewer Advertisements

From Google's Contributor website: Contribute a few dollars each month. See fewer ads. The money you contribute helps fund the sites you visit.

Google-Contributor supports websites while reducing advertisements. You can support InspectApedia with a contribution of any amount you wish. Or you can contribute nothing and we'll still keep our website free to all readers - supported by advertising. Either approach is OK.