metal electrical junction box sizes

2021/05/21

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Learn about the differences so you can feel confident that youre choosing the right box for your project. Had the box been omitted there is a good chance the fire would have spread to the building itself. NEMA Type 3R Junction Box, Screw Cover-Hinged Lid, Galvanized Steel, Knockouts, 24 x 24 x 8 in.

NEMA Type 3R Junction Box, Screw Cover-Hinged Lid, Galvanized Steel, Knockouts, 24 x 24 x 12 in.

Many local building codes require metal junction boxes because they are durable and ensure long-lasting performance. Plumbing Code (UPC) and the 2005 National Electrical Code.". I was looking at some height requirements on electrical outlets this is a very informational site.thanks Jerm 4/19/12. 8155 T&B Boulevard Please call us at: 1-800-HOME-DEPOT (1-800-466-3337), Please enter in your email address in the following format: you@domain.com.

Obviously the front of the box as a single opening into which devices are secured. NEMA Type 3R Junction Box, Screw Cover-Hinged Lid, Galvanized Steel, Knockouts, 12 x 12 x 8 in. Do I really need an electrical box to put a new wall plug in ? NEMA Type 3R-Small Junction Box, Hinge Cover, Galvanized Steel, Knockouts, 6 x 6 x 4 in.

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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. Is there a way to repair electrical outlets on finished (glass and ceramic tile) walls that were not installed properly without damaging the tile? 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. 5 F+ % W(`T s$Hf/b3f)}iq@ v# endstream endobj 66 0 obj 189 endobj 35 0 obj << /Type /Page /Parent 31 0 R /MediaBox [ 0 0 604 779 ] /Resources 36 0 R /Contents [ 44 0 R 46 0 R 48 0 R 50 0 R 52 0 R 54 0 R 60 0 R 62 0 R ] /Thumb 25 0 R /CropBox [ 0 0 604 779 ] /Rotate 0 >> endobj 36 0 obj << /ProcSet [ /PDF /Text /ImageC ] /Font << /F3 38 0 R /F4 58 0 R /F5 57 0 R /F6 42 0 R /F7 41 0 R >> /XObject << /im1 64 0 R >> >> endobj 37 0 obj << /Type /FontDescriptor /FontName /F3 /Ascent 891 /Descent 216 /StemV 131 /CapHeight 891 /Flags 98 /FontBBox [ -547 -307 1206 1032 ] /ItalicAngle -164 >> endobj 38 0 obj << /Type /Font /Subtype /Type1 /Name /F3 /BaseFont /Times-BoldItalic /Encoding /WinAnsiEncoding /FirstChar 31 /LastChar 255 /Widths [ 778 250 389 555 500 500 833 778 278 333 333 500 570 250 333 250 278 500 500 500 500 500 500 500 500 500 500 333 333 570 570 570 500 832 667 667 667 722 667 667 722 778 389 500 667 611 889 722 722 611 722 667 556 611 722 667 889 667 611 611 333 278 333 570 500 333 500 500 444 500 444 333 500 556 278 278 500 278 778 556 500 500 500 389 389 278 556 444 667 500 444 389 348 220 348 570 778 500 778 333 500 500 1000 500 500 333 1000 556 333 944 778 778 778 778 333 333 500 500 350 500 1000 333 1000 389 333 722 778 778 611 250 389 500 500 500 500 220 500 333 747 266 500 606 333 747 500 400 549 300 300 333 576 500 250 333 300 300 500 750 750 750 500 667 667 667 667 667 667 944 667 667 667 667 667 389 389 389 389 722 722 722 722 722 722 722 570 722 722 722 722 722 611 611 500 500 500 500 500 500 500 722 444 444 444 444 444 278 278 278 278 500 556 500 500 500 500 500 549 500 556 556 556 556 444 500 444 ] /FontDescriptor 37 0 R >> endobj 39 0 obj << /Type /FontDescriptor /FontName /F6 /Ascent 905 /Descent 212 /StemV 153 /CapHeight 905 /Flags 32 /FontBBox [ -628 -376 2034 1048 ] /ItalicAngle 0 >> endobj 40 0 obj << /Type /FontDescriptor /FontName /F7 /Ascent 905 /Descent 212 /StemV 153 /CapHeight 905 /Flags 96 /FontBBox [ -560 -376 1157 1031 ] /ItalicAngle -120 >> endobj 41 0 obj << /Type /Font /Subtype /Type1 /Name /F7 /BaseFont /Helvetica-BoldOblique /Encoding /WinAnsiEncoding /FirstChar 31 /LastChar 255 /Widths [ 750 278 333 474 556 556 889 722 238 333 333 389 584 278 333 278 278 556 556 556 556 556 556 556 556 556 556 333 333 584 584 584 611 975 722 722 722 722 667 611 778 722 278 556 722 611 833 722 778 667 778 722 667 611 722 667 944 667 667 611 333 278 333 584 556 333 556 611 556 611 556 333 611 611 278 278 556 278 889 611 611 611 611 389 556 333 611 556 778 556 556 500 389 280 389 584 750 556 750 278 556 500 1000 556 556 333 1000 667 333 1000 750 750 750 750 278 278 500 500 350 556 1000 333 1000 556 333 944 750 750 667 278 333 556 556 556 556 280 556 333 737 370 556 584 333 737 552 400 549 333 333 333 576 556 278 333 333 365 556 834 834 834 611 722 722 722 722 722 722 1000 722 667 667 667 667 278 278 278 278 722 722 778 778 778 778 778 584 778 722 722 722 722 667 667 611 556 556 556 556 556 556 889 556 556 556 556 556 278 278 278 278 611 611 611 611 611 611 611 549 611 611 611 611 611 556 611 556 ] /FontDescriptor 40 0 R >> endobj 42 0 obj << /Type /Font /Subtype /Type1 /Name /F6 /BaseFont /Helvetica-Bold /Encoding /WinAnsiEncoding /FirstChar 31 /LastChar 255 /Widths [ 750 278 333 474 556 556 889 722 238 333 333 389 584 278 333 278 278 556 556 556 556 556 556 556 556 556 556 333 333 584 584 584 611 975 722 722 722 722 667 611 778 722 278 556 722 611 833 722 778 667 778 722 667 611 722 667 944 667 667 611 333 278 333 584 556 333 556 611 556 611 556 333 611 611 278 278 556 278 889 611 611 611 611 389 556 333 611 556 778 556 556 500 389 280 389 584 750 556 750 278 556 500 1000 556 556 333 1000 667 333 1000 750 750 750 750 278 278 500 500 350 556 1000 333 1000 556 333 944 750 750 667 278 333 556 556 556 556 280 556 333 737 370 556 584 333 737 552 400 549 333 333 333 576 556 278 333 333 365 556 834 834 834 611 722 722 722 722 722 722 1000 722 667 667 667 667 278 278 278 278 722 722 778 778 778 778 778 584 778 722 722 722 722 667 667 611 556 556 556 556 556 556 889 556 556 556 556 556 278 278 278 278 611 611 611 611 611 611 611 549 611 611 611 611 611 556 611 556 ] /FontDescriptor 39 0 R >> endobj 43 0 obj 1003 endobj 44 0 obj << /Filter /FlateDecode /Length 43 0 R >> stream The boxes made without metal are PVC or plastic. These boxes are inexpensive and easy to install. Contact Mr. Cranor at 804-873-8534 or by Email: [3] NFPA - the National Fire Protection Association can be found online at www.nfpa.org, [4] The 2008 NEC National Electrical Code (ISBN 978-0877657903). Anne,I'm in the midst of a remodel that posed the same 'problem'. 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. Specific boxes are designed for indoor or outdoor use, while others are made for installation behind or outside of walls. Work box extender rings are available at Home Depot and Lowes in the electrical department. Details about how to wire up an electrical receptacle are. 0000005629 00000 n [DF NOTE: I do NOT recommend this obsolete publication, though it was cited in the original. The number of those will vary as the box size varies. No, Justin. A ceiling box is for heavier fixtures, such as ceiling fans or chandeliers. Jerm, in the article above at ELECTRICAL RECEPTACLE HEIGHT & CLEARANCES we give the data you want. Try using a saber saw for wood. Back toConduit, Raceway and Cable Support, Back toElectrical Distribution Equipment, Back toHeating, Ventilation and Air Conditioning, Back toIndustrial and Maintenance Supplies, Back toIndustrial Control and Automation. "Electrical Systems," A Training Manual for Home Inspectors, Alfred L. Alk, American Society of Home Inspectors (ASHI), 1987, available from ASHI.

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. 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. NEMA Type 3R Junction Box, Screw Cover-Hinged Lid, Galvanized Steel, Knockouts, 18 x 18 x 6 in. 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. NEMA Type 1-Medium Junction Box, Hinge Cover, Painted Steel, Equipment Mounting Studs, 16 x 16 x 6.62 in. =TgR(Mo|}6SI@ IUMtw@bJ]hl F(z {YbY ACIV!A@&B]m}&msMJW_3u B7O- 5&.9Xi?=.3SMQ1\W"qQ)Qlh|kVltxeldKN(fmvm.Z~xx!qHN~/V[XAl0_~}~\d~=/dwPh y0Erj%kg4 y)Q (W%jMIqg2>sPzf+(]S.' rd)'7z"eSIvhjuP2Q$g@!^&$Fw{Z2FOe-v ? NEMA Type 3R-Medium Junction Box, Hinge Cover, Galvanized Steel, Knockouts, 16 x 12 x 6 in. They come in many shapes and sizes to fit wherever you need them. 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. At the very least I would prefer to run two or more 20 A circuits to that location and connect the receptacles accordingly so that you don't simply overload the circuit. thanks, - Anon.

- Anne 3/22/12. It could be simply tightening screws, or it could be that the electrical box itself is not adequately secured in the wall. Reader Question: Do I really need an electrical box to put a new wall plug in ? Junction Box, PVC, Screw Mount Cover, 12 x 12 x 6 in. 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. 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.

For new construction/remodeling permit , is one box no matter the size, single, double or multi switch considered one opening. He is also a contributor to InspectApedia.com in several technical areas such as plumbing and appliances (dryer vents). 0000003047 00000 n 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.

Junction Box, PVC, Screw Mount Cover, 8 x 8 x 4 in. 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. Carlon NEMA Type 6P Junction Box, Foam-in-Place Gasketed Lid, Molded, Thermoplastic, 12 x 12 x 6 in. They can contain light switches, wires or outlets. 1. Junction Box, PVC, Screw Mount Cover, 6 x 6 x 6 in. 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. Phone: 901-252-5000, Phone: 800-816-7809 [5] Special thanks to our reader Steve who pointed out prior errors in our illustrations. 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. I eliminated one receptacle (capping the 3 wires together) but want to keep the other. The minimum order quantity is {0} {1}. - Thomas. %PDF-1.3 % Why are there different sizes of outlet boxes in a commercial construction, The answer to your perfectly good question depends on the cubic inches that the Box provides matched against the table of cubic inches required for the number of wires and connectors by wire size in the circuit that you are wiring. Always check with your local building inspector before starting any electrical project. As we discuss. For new construction installations, diagram the room and be sure you have enough electrical boxes to accommodate all the light switches, outlets and fixtures you need. Thanks. I would think in a garage fire that a plastic box would melt and fire would go through the wall faster? At above right in addition to aluminum wiring hazards the box is overcrowded. NEMA Type 3R-Medium Junction Box, Hinge Cover, Galvanized Steel, Knockouts, 24 x 24 x 10 in. NEMA Type 4X Enclosure, Clamp Cover, Stainless Steel, 4 x 4 x 3 in. Add new lights, ceiling fans or other appliances to enhance your decor. - Bob M. Yes, Greg, that's a common practice. 12. NEMA Type 3R-Medium Junction Box, Hinge Cover, Galvanized Steel, Knockouts, 18 x 18 x 10 in. This weatherproof box is designed to provide an outdoor electrical receptacle. Also the electrical box(es) or gang box needs to be big enough to permit all of the electrical connections, wires, and devices. Scepter Jbox, Screw Cover, PVC, Molded Mounting Feet, 6 x 6 x 4 in. Junction Box, PVC, Screw Mount Cover, 16 x 14 x 6 in. Plan for future changes by clearly labeling all wires.

0000015227 00000 n 0000003226 00000 n - Steve Smith. 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. Electrical boxes, also known as junction boxes, enclose wire connections. NEMA Type 3R Junction Box, Screw Cover-Hinged Lid, Galvanized Steel, Knockouts, 18 x 18 x 8 in. I'm sorry but I'm confused by the question. 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. Not the outlet box, but the wire running through the joists. See ALUMINUM WIRE REPAIR SPLICE SPACE where we discuss all of the approaches to obtaining more wiring or device space in electrical boxes.

- Gary 7/19/12.

0000007718 00000 n 0000006753 00000 n ELECTRICAL JUNCTION BOX TYPES at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice. Choose from many junction box sizes to find the one that best suits your project. Do I move forward the box to which the outlet is screwed and if so how? Junction Box, PVC, Screw Mount Cover, 6 x 6 x 4 in. This is to ensure that the electrical boxes have been safely installed. Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia. InspectAPedia tolerates no conflicts of interest. MikeYou are certainly allowed to install a cluster of electrical receptacles, and I've done that many times myself.

Below: a weatherproof electrical box and receptacle mounted on a home in northern Minnesota. 10 electrical receptacles to be wired on a 15-Amp (#14 copper) wire circuit, and the Electrical Code [NEC] allows.

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

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. from the 2003, 2006 and 2009 International Residential Code 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.

I need to install a cluster of 10 receptacles on a center wall to support a home computer lab. NEMA Type 3R-Small Junction Box, Hinge Cover, Galvanized Steel, Knockouts, 10 x 8 x 6 in. GlenI'm not sure how you're using the word opening or where the concern lies in the question. HWr6~v,c9tI:bZYru H(,)4,W$P(K|&l7wunqO:UW]tVY'enSpGg 0000012033 00000 n I am putting outlet in garage wall that has kitchen on the other side. 0000015248 00000 n NEMA Type 3R Junction Box, Screw Cover-Hinged Lid, Galvanized Steel, Knockouts, 12 x 12 x 4 in. "Simplified Electrical Wiring," Sears, Roebuck and Co., 15705 (F5428) Rev. Make sure they don't interfere with the placement of a new box. If one of the two circuits should be switched off by a circuit breaker (perhaps detecting a fault or over current) we want the other circuit to remain on so that room occupants are less likely to be left in darkness. Be sure to choose a ceiling box that is made to support extra weight.

Just decide on the location and choose the right junction box for the job. Gang boxes are steel electrical boxes with removable sides and screw fittings that permit multiple metal boxes to be joined together to obtain more space. What is code, plastic or metal? LakeWe use electrical boxes of varying sizes or capacity (in cubic inches) because the number of electrical wires, connectors, devices varies as well. When youre done, always have your work inspected for compliance with local codes. 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. Local store prices may vary from those displayed. "Home Wiring Inspection," Roswell W. Ard, Rodale's New Shelter, July/August, 1985 p. 35-40. Junction Box, PVC, Screw Mount Cover, 4 x 4 x 2 in. 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. Junction Box, PVC, Screw Mount Cover, 4 x 4 x 4 in. 0000001940 00000 n

Or see ELECTRICAL BOX TYPE FAQs - questions & answers posted originally at this article. 0000006732 00000 n 0000010885 00000 n 12/13/12. trailer << /Size 67 /Info 32 0 R /Root 34 0 R /Prev 1404417 /ID[<820c601cffdef728c41fcaf9c8f4f746><820c601cffdef728c41fcaf9c8f4f746>] >> startxref 0 %%EOF 34 0 obj << /Type /Catalog /Pages 31 0 R >> endobj 65 0 obj << /S 84 /T 194 /Filter /FlateDecode /Length 66 0 R >> stream 33 0 obj << /Linearized 1 /O 35 /H [ 1082 301 ] /L 1405205 /E 496240 /N 3 /T 1404427 >> endobj xref 33 34 0000000016 00000 n Search by City/State or Zip Code to find a location near you. When running wire for a basement, is there a min height the wires must be off the ground? The frames are available in multiple thicknesses. Depending on the thickness of the tile, you may need to combine two frames of different thicknesses. Are CSA approved plastic box extenders code compliant for homes? 0000010864 00000 n 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. The electrical box extender is sized and shaped to match the electrical receptacle box to which it is to fit. 0000007739 00000 n They'll ensure that you are following code. Light switches are generally installed about 42 inches from the floor. Watch out: IMO if your light is within touching distance of the sink it should be GFCI protected as well.See OLD WORK ELECTRICAL BOXES for RETROFIT. THIS ITEM IS ONLY AVAILABLE DIRECTLY FROM THE VENDOR. We have no relationship with advertisers, products, or services discussed at this website. See details at OLD WORK ELECTRICAL BOXES for RETROFIT. Enter City/State or Zip Code to see results. Take a look at our photograph at left - a fire was contained within this electrical junction box. 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. 2. I will be installing a new wall mount light fixture in a powder room (toilet and sink only). At above 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. Anon: Luckily, the breaker box is only about 10 feet away.The receptacle layout would look like this: NEMA Type 1 Enclosure, Screw Cover, Painted Steel, 12 x 12 x 6 in. Below 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. Electrical box extensions are sold in plastic and steel and in thicknesses from about 1/8" up to an inch or even more. I 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. 0000016302 00000 n NEMA Type 3R-Medium Junction Box, Hinge Cover, Galvanized Steel, Knockouts, 16 x 16 x 6 in. Hb`````b`e`3Icd@ A6 se P)+M4`hT2Ti9 V3H*0 048?`apP`c`P )y , [] [] [] [] [] They'll have a combination outlet/switch or a pair of outlets/switches inside. Utility knives work well for cutting holes in drywall, and keyhole saws are good for plaster. Need Help? aM s v16cQ=\G)5-zxc 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. They help protect against short circuits, which can cause fires.

I also want to run a dedicate 15 amp circuit. 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. Metal boxes are usually made of aluminum, steel or cast iron. Shop online to get the supplies you need for your project. NEMA Type 3R Junction Box, Screw Cover-Hinged Lid, Galvanized Steel, Knockouts, 12 x 12 x 6 in. [6] Simpson Strong-Tie, "Code Compliant Repair and Protection Guide for the Installation of Utilities in Wood Frame Construction", web search 5/21/12, original source strongtie.com/ftp/fliers/F-REPRPROTECT09.pdf, [copy on file as /Structures/Framing/Simpson_Framing_Protectors.pdf ]. See ELECTRICAL RECEPTACLE HEIGHT & CLEARANCES for details. JodieThank you for a helpful question on electrical box size for two light switches. Is it safe to just run a pigtail from the 3 wires to the receptacle? 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. Justin Sheppard.

In this installation the box and receptacle are installed high on the building exterior wall, under the soffit. Will I need to install a junction box and make the splice between the wire and light within the junction box? IMPORTANT: The National Electrical Code (NEC) and local building codes regulate the types of electrical boxes allowed in certain applications, as well as how theyre installed. If we lose power on one circuit we want the other still working so that there is safe lighting in the area. Use for exposed indoor applications, such as with conduit in an unfinished basement. GFCI protection is also required. "Electrical System Inspection Basics," Richard C. Wolcott, ASHI 8th Annual Education Conference, Boston 1985. Power outlets are generally installed 12 inches from the floor. Memphis, TN 38125 With a bit of preparation, you can add electrical boxes to your home. 0000004522 00000 n NEMA 1 Steel 6 x 6 x 4 in. 2022 Graybar Electric Company, Inc., all rights reserved. Bob, similar to Greg's question, I see two approaches to hooking up the ground wire in junction boxes and at electrical receptacles. Ready to get started? 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. NEMA Type 3R-Small Junction Box, Hinge Cover, Galvanized Steel, Knockouts, 12 x 10 x 6 in. 0000001027 00000 n 0000016326 00000 n 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. Email: elec_custserv@tnb.com Website: http://www.tnb.com/, Local electrical contracting suppliers in your area. "Evaluating Wiring in Older Minnesota Homes," Agricultural Extension Service, University of Minnesota, St. Paul, Minnesota 55108. 4-77 1977 [Lots of sketches of older-type service panels.].

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? Scepter Jbox, Screw Cover, PVC, Molded Mounting Feet, 12 x 12 x 8 in. While I was changing a failed plug I noticed that the box was too deep. Good luck on your test. I 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. That's nonsense. 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.) If you are asking about using a shared neutral wire on a lighting circuit combined with an electrical receptacle circuit, see (search InspectAPedia.com for) our article on "multi wire branch circuits" or "shared neutral electrical wiring". But an inspection is needed to understand the underlying problem.

A square electrical box, also known as a double-gang box, houses two devices. Junction Box, PVC, Screw Mount Cover, 8 x 8 x 7 in.