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Home Electrical Wiring

home electrical wiring

Typical home electrical cable has a bare ground wire and two insulated wires inside.

Home electrical wiring can seem mysterious, but have no fear: This helpful guide will help you understand how wiring works and how to work with wire.

“Electrical wire” is a catchall term that refers to conductors that route electricity from a power source to lights, appliances, and other electrical devices.

Wires and cables of various sizes bring electricity to a house and route it to all the lights, switches, receptacles, and electrical appliances. Generally speaking, large cables deliver electricity to the house and smaller cables and wires distribute it throughout.

Nonmetallic cable is routed between wall studs; switches and receptacles fasten to electrical boxes.

Nonmetallic cable is routed between wall studs; switches and receptacles fasten to electrical boxes.

Nearly all household wire is copper, though aluminum is occasionally used. A rubber, plastic, or paper-like coating, called insulation, serves as a barrier to keep the electrical charge (and heat) where it belongs—in the wire (this insulation is stripped from the ends of the wires where connections are made). Bare (non-insulated) conductors are used for grounding.

How Electrical Wiring Works

Wire is a comprehensive term commonly used to refer to all types of cable and wire. Technically, an individual wire is called a single conductor; several single conductors twisted together or combined together in a sheath make a cable.

Just as highways can handle more cars than small streets, large conductors can handle more electricity than small ones. The diameter of a metal conductor is indicated by an AWG (American Wire Gauge) number; the smaller the number, the larger the wire. Most household lighting and receptacle circuits are wired with AWG 14 or AWG 12 conductors.[GARD align=”right”]

In addition to standard electrical wire, a house has several other types of wire needed for the telephone, cable television, stereo speakers, and so on. Most of these wires do not carry a dangerous electrical current because they operate on very low voltage or carry only sound or picture signals, not electrical power.

In this section of HomeTips, you will learn more about the Types of Electrical Wiring and the Types of Wires & Cables.

Electrical Wire Repair & Care

Electrical circuits can incur any number of problems, and, because of the potential fire hazard faulty wiring can present, it is important to diagnose and repair a problem immediately. In Electrical Wiring Repairs, we take you through a list of the most common problems and refer you to other articles that will help you narrow down the possibilities. One of the most common problems occurs with electrical cords and plugs, which can deteriorate after years of use. We show you how to replace them.[GARD align=”right”]

DIY Electrical Wiring Projects

This section of Electrical Wiring is devoted to the many home wiring projects you can do yourself. First we walk you through some basic techniques, such as How to Cut & Strip Wires and How to Cut & Rip Electrical Cable. Then we walk you through such common projects as How to Extend an Electrical Circuit and How to Mount a New Electrical Box. As with all do-it-yourself tasks involving electricity, make sure the power to the circuit from the main panel is turned off before attempting any repairs or installations.

How to Splice Electrical Wires

Splicing wires is easy with the right tools and a basic understanding of this simple process.wire stripper and wire nuts

When working on an electrical project, taking care that all the connections are made well and will last isn’t just about getting the job done right, it’s also a matter of safety. Poorly joined, or spliced, wires can lead to electrical shorts and become a fire hazard.[GARD align=”left”]

There are two kinds of connectors used to splice wires together safely and strongly—wire nuts and compression sleeves. Which connector you use will depend on your project and your local building codes.

Working with Wire Nuts

Wire nuts are thimble-shaped connectors made from a hard plastic that twists over the ends of wires to connect them. Because wire comes in many different sizes, or gauges, finding the right-size wire nut for your project is crucial. Wire nuts are color-coded to distinguish their sizes, which range from the smallest, gray-colored #22 American Wire Gauge (AWG) to the largest, red-colored #10 AWG. Using a wire gauge to measure the wire you will be splicing will help you choose the right wire nut for the job.

wirenut

Wire nut, twisted onto the bare ends of stripped wires, makes a solid connection.

Once you have the right-size wire nut for the project, making a connection is easy:

1Strip about 1 inch of insulation from the ends of the wires being spliced together using a proper insulation stripper, not a knife. Twist the ends of the wire together clockwise one to one and one-half twists.

2Evenly trim about 1/2 inch off of the ends of the twisted wires.

 

3Screw the wire nut clockwise onto the twisted wires until it is tight enough that it does not come loose when tugged. Make sure no bare wires are exposed.

Wire nuts are fast and easy to use and can easily be taken off to disconnect wires. For more-permanent connections, though, a compression sleeve should be used.

Working with Compression Sleeves

Compression sleeves provide a more permanent bond than wire nuts, and for this reason some local building codes require their use. Shaped like bullet casings with the ends cut off, some compression sleeves have the added feature of being insulated.

Though putting on compression sleeves is a little more complicated than putting on wire nuts, they are perfect for projects where durability is paramount.

To splice wires to receive a compression sleeve:[GARD align=”right”]

1Strip the insulation from the ends of the wires, exposing about 1 inch of metal, and twist the wires together about one and a half times.

2Trim the ends of the wires about 1/2 inch.

 

3Slip the compression sleeve over the ends of the twisted wires and crimp them using the jaws of a wire stripper or a special crimping tool. To ensure the metal is in tight contact with the wires, be sure to use enough pressure.

Some codes require the use of an insulating cap on the ends of the wires, so be sure to check. Also, when splicing aluminum wire to copper wire, use a special two-compartment connector.

Just like duct tape should never be used to seal ducts, electricians’ tape should never be used in place of wire nuts or compression sleeves. Also, as with any electrical project, make sure that all power is turned off from the breaker box before stripping insulation or making connections.

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How to Cut & Rip Electrical Cable

The correct tools and techniques to properly cut and rip Romex or similar electrical cable

Cables are cut to length at the rough-wiring stage; ripping is done when wiring devices.

Cutting cable doesn’t require much instruction—just use lineman’s pliers or heavy-duty diagonal cutters to snip it in half.[GARD align=”left”]

Opening up nonmetallic cable to expose the individual conductors inside is called “ripping.” To rip a flat (not round) cable, you can use either a utility knife or a cable ripper, as shown at right. To use a cable ripper, you slide it over the cable, squeeze the body so that the cutter penetrates the outer sheath, and drag it off toward the end of the wire. Use a utility knife to rip round cable, carefully follow the wire’s contours to avoid cutting or nicking into the wires inside.

When ripping either kind of cable with a utility knife, always work on a flat horizontal or vertical surface and cut away from your body, never toward it.

 

Slide the cable ripper onto a flat cable.

1Slide a cable ripper onto a flat cable. Press the handles together and pull to score the sheath.

 

 

Bend the cable until the scoring cracks.

2Bend the cable until the scoring cracks, and then peel away the outer sheath and all separation materials to expose the wires.

 

 

 

Cut off the peeled sheath.

 

 

3With diagonal-cutting pliers, cut off the peeled sheath and other separation materials, leaving just the wires.

How to Cut & Rip Electrical Cable

The correct tools and techniques to properly cut and rip Romex or similar electrical cable

Cables are cut to length at the rough-wiring stage; ripping is done when wiring devices.

Cutting cable doesn’t require much instruction—just use lineman’s pliers or heavy-duty diagonal cutters to snip it in half.[GARD align=”left”]

Opening up nonmetallic cable to expose the individual conductors inside is called “ripping.” To rip a flat (not round) cable, you can use either a utility knife or a cable ripper, as shown at right. To use a cable ripper, you slide it over the cable, squeeze the body so that the cutter penetrates the outer sheath, and drag it off toward the end of the wire. Use a utility knife to rip round cable, carefully follow the wire’s contours to avoid cutting or nicking into the wires inside.

When ripping either kind of cable with a utility knife, always work on a flat horizontal or vertical surface and cut away from your body, never toward it.

 

Slide the cable ripper onto a flat cable.

1Slide a cable ripper onto a flat cable. Press the handles together and pull to score the sheath.

 

 

Bend the cable until the scoring cracks.

2Bend the cable until the scoring cracks, and then peel away the outer sheath and all separation materials to expose the wires.

 

 

 

Cut off the peeled sheath.

 

 

3With diagonal-cutting pliers, cut off the peeled sheath and other separation materials, leaving just the wires.

How to Mount a New Electrical Box

Metal electrical box utilizes cable clamps to secure nonmetallic cable.

Metal electrical box utilizes cable clamps to secure nonmetallic cable. This “four-gang” box is designed to hole four switches or receptacles.

Mounting new electrical boxes is a simple process, but the job does require careful planning.

Whether you are upgrading the electrical in an old home or planning your electrical needs for new construction, it helps to draw out your plans on paper. You don’t have to create a to-scale rendering for it to be a helpful tool when adding new circuitry.

Nail-on plastic electrical boxes are affordable and easy to use.

Nail-on plastic electrical boxes are affordable and easy to use. Note the nails in the the mounting bracket or the flat flanges.

Before you buy the electrical boxes, you want to be certain they have the right mounting holes for the devices you plan to install. For instance, you might discover that an adapter plate will be helpful in the process of mounting a particular new box. You also want to be sure the boxes have correctly placed knockout holes for routing cable in and out. Some boxes have built-in clamps for securing cable, or you might need to purchase cable connectors.

Electrical boxes that are mounted to wall studs during new construction must be positioned so that, when drywall is added, the face of the box will be flush with (or very slightly inset from) the wall’s surface. This generally means mounting them so they extend 1/2 inch beyond the face of the wall studs. Be sure they don’t protrude further than the thickness of the wall-covering material—you’re better off mounting them so that they sit about 1/16-inch shy of the wall’s surface so the cover plate will sit flat against the wall.[GARD align=”left”]

Keep in mind that receptacles should be placed a consistent 12 to 18 inches above the floor. Also, avoid placing a switch box on the hinge side of a door opening; you want the switch to be readily accessible upon opening the door.

Boxes, whether metal or nonmetallic, should be simple and straightforward to mount using one of the following techniques:

• Screw-on handy box—attach this box directly to the framing.

Nail-on electrical box is easily nailed in place. Note that the face of the box extends out 1/2-inch from stud to allow for drywall.

[/media-credit] Nail-on electrical wall box is quick and fast to nail in place. Note that the face of the box extends out 1/2-inch from stud to allow for drywall.

• Box with flange—nail the flange to the side of an exposed stud or joist, aligning the front so that it will be flush with the finished ceiling or wall.

• Nail-on electrical wall box—butt this box against a wall stud and nail it on.

• Adjustable hanger bar—when a ceiling box spans two joists, this two-piece bar can be narrowed or expanded to fit the space between them. As a plus, the box will slide along the bar, allowing you to create the perfect placement for a lighting fixture.

• Pancake box—while this application has nothing to do with breakfast, its ease of installment makes it an option you might just “flip” over.

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How to Route Electrical Cable in New Construction

Routing cable in new construction is easy, but you should first sketch out your plan on paper.

Installing rough wiring in new construction is done before the wall, ceiling, and floor coverings are in place. Nonmetallic sheathed cable—known as type NM—is common for new construction.

While there are situations when you will have to route cable through structural members such as studs, joists, and rafters, the job is much easier if you can run the cable along the surfaces of these frames.

Running Cable Through Studs

When you have a situation where you need to run cable through wall studs, follow these steps:[GARD align=”right”]

1Drill a series of 3/4-inch holes through a run of new wall studs at an equal distance from the top or bottom of each stud. Drill in the center of each stud.

2Measure for the amount of cable you will need. Include the height of boxes from the floor and the distance between boxes. Add at least an extra 4 feet to allow for unforeseeable obstacles.

3Run the cable through the holes you drilled in the studs or joists toward the new receptacle box, taking care not to kink or twist the cable.

Securing Cable

armored_cable_h1In new construction, cable must be stapled or supported with straps every 4 1/2 feet; it also must run within 12 inches of each metal box or within 8 inches of each nonmetallic box. You can use cable staples, but be careful not to staple through the cable. You can also use metal plates to protect cable that is installed near the edge of a stud or joist.

Cable staples or supports aren’t necessary when the cable is concealed. But the cable must be clamped to boxes using built-in cable clamps, metal cable connectors, or plastic cable connectors. NM cable does not need to be clamped to a nonmetallic box if it is stapled within 8 inches of the box.

Routing Around Doors & Windows

Windows are a little simpler to bypass than doors since most have stud framing below the sill through which you can run the cable. With doors, however, it is best to route the cable through the ceiling above or the floor below, if possible. If neither of these is an option, you will need to run the cable through the cripple studs above the header or through the shim space just below the header.

Routing Tricky Corners

An intersection where stud walls meet may present a challenge for routing cable. It may be easier to route the cable above or below the area in question. If the corner is hollow, you can drill holes in the studs from both sides and run the cable through them.

Unfinished Basement

If you are routing the cable under the floor at an angle to the floor joists, NM cable with two conductors smaller than #6 or three conductors smaller than #8 should be run through holes drilled in the joists and then stapled to the running boards. Or, you can support the cable on the surface of structural members; just fasten larger cable directly to the bottom edges of joists.[GARD align=”right”]

Routing Cable in an Attic

When running cable in an attic, you can run it either on top of the joists or through holes drilled in them, depending on their accessibility. In the case of an attic with a permanent staircase or ladder, run the cable at an angle to the structural members and protect it with guard strips. If the attic is accessed through a crawl hole with no permanent stairs or ladder, protect the cable within 6 feet of the hole with guard strips; beyond that distance, simply lay the cable on top of the ceiling joists. If the cable runs parallel to the joists, you can staple it to the sides of the joists.

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