By Clint C. Thomas, Esq.
Photography by Zoe Thomas
How To Wire A House
Electrical work, like everything else in life, can run the gamut from very basic to extremely complex. It is helpful for every DIY-minded homeowner to have at least a basic understanding of electrical work. This article will attempt to reveal some of the mystery surrounding the maze of wiring that runs throughout your home and that makes everything in it work with the flick of a switch.
Electricity enters every home by running through a power meter supplied by the local utility company, then, in most cases, through a master 200-amp circuit breaker, and then to the home’s breaker box, often still referred to as a fuse box .From the breaker box, this flow of electricity is spread over numerous circuits to different parts of the home by first passing through individual circuit breakers which serve as a safety mechanism to keep the system from being overloaded. A home’s electrical system is designed to work off 120 volts with the exception of certain major appliances, such as an electric clothes dryer, which runs off 240 volts.
Household Wire Gauge
Electrical wiring comes in different gauges, or sizes. The heavier the gauge, i.e., the thicker the copper wire, the more electrical current it can carry without overheating. Electrical wire and circuit breakers are designed to work in tandem with one another, and each must be of a proper corresponding size. For example, 14/2 gauge electrical wire is rated to a maximum of 15 amps and should not be used with any circuit breaker larger than 15 amps.12/2 gauge wiring is rated to a maximum of 20 amps. These two size wires are the standard that are used in homes today for most lighting and wall outlets. Again, heavier gauges and higher amp circuit breakers must be used for certain appliances that use more electricity and as dictated by local and state building codes.
Electrical wire is gauged like shot for a shotgun. The smaller the number the heavier gauge the wire. Twelve-gauge wire is heavier and will carry more of a load than 14-gauge wire but is smaller than 10-gauge wire and will carry less of a load than the 10 gauge.
If the improper gauge wire is used with the wrong size circuit breaker, it can easily result in a fire or a malfunctioning electrical circuit. For example, if a wire of too small gauge is used with a high amp break, then the wire can overheat and catch fire long before the circuit breaker ever trips. On the other hand, if a too large of a gauge wire is used with a low amp breaker then the breaker may continuously trip, disrupting the circuit before the wire ever reaches its maximum electrical load.
It is imperative to know exactly what gauge wire and what amp breaker have to be used for any given application. This is not an area to guess-timate. The result of such guesswork can be a house fire or someone being electrocuted. Also, there are limits under the applicable building codes to how many outlets and/or lights, etc., that a particular circuit can have on them, and even where they can be placed or not placed. Be sure to consult your local and state building codes before beginning any electrical work.
Types of Household Wires
Typical electrical wire for home use comes in an insulated sleeve and consists of three wires. A black wire carries the electrical current and is therefore commonly known as the “hot” wire. There is a white wire that is the “neutral,” and, finally, a bare copper wire that is the ground wire. When electrical wires are joined together the black wires must be hooked together, the white wires must be hooked to the white wires, and the ground wires must be hooked together. Otherwise, the circuit will not work, and will result in an electrical “short.”
Three-conductor electrical wire is available for use with applications that require an additional “hot” wire, such as with a three-way switch. A total of four wires are found in three-conductor wiring: A white neutral wire, a bare copper ground wire, a black “hot” wire and a red wire for a second “hot” wire.
First and foremost, always disconnect the electrical power supply before working with any part of the electrical system.
For applications such as wiring a light fixture, the fixture’s wires are joined to the electrical supply wires with wire nuts. Like the wire itself, wire nuts come in different sizes to accommodate the various gauges of wire. To connect, strip back the insulation from the ends of the wires, hold them between your fingers and twist the wire nut in a clockwise direction onto the ends.
Light switches and wall outlets have screws on both sides for connecting wires. The green screws are for the ground wires, the silver/stainless colored screws are for the white neutral wires and the brass colored screws are for the black “hot” wires.
Some of the most common electrical projects that a homeowner will encounter are replacing light switches and wall outlets. Room additions or major renovations may even involve having to increase the number of wall outlets in a particular area of your home. Therefore, the scope of this article will be confined to the most basic of electrical jobs using only single-pole switches and end-of-run receptacles.
Light switches simply serve to disrupt, or “break,” the flow of electricity in the wiring before it gets to the light fixture. This interruption in the flow is what turns the light off, and then back on. To connect a switch, imagine a wire running from a “hot” junction point to the box that will contain the light switch. Another wire will lead from that light switch box to the junction box that contains the light fixture. The switch itself is what will connect these two wire runs and allow the electrical current to flow to the light or to be stopped at the switch.
Route the ends of the two wires in the switch box, strip the ends and then connect the white wires together with a wire nut and the ground wires together by securing them around the green screw on the bottom of the switch. The black wires are each attached to the switch. One wire is attached to each brass screw on the right-hand side of the switch.
Wall outlets are the other area that may require a homeowner’s attention .Unlike a light fixture, wall outlets remain “hot,” meaning that they always have live electrical current in them, all of the time. This is achieved by outlets being connected together in a row much like the lights on a Christmas tree. A “hot” wire will come from a circuit breaker or other “hot” junction box and lead to the first wall outlet. From there another wire is run from the first wall outlet to the second wall outlet. This continues until the entire room has been hooked-up or until the maximum number of fixtures has been attached to a particular circuit.
Receptacles, also known as outlets or plugs, are connected in a row, so-to-speak, by attaching the black wires to the brass screws, the white wires to the silver/stainless metal screws and the ground wire to the green screw at the bottom. Modern receptacles are called “duplex receptacles” because they have two screws on both sides. As the name implies, they can bring electrical current into one set of screws and then send it out on the other “duplex” set of screws to another fixture.
Wires are attached to the receptacles and switches by bending the end into a hook shape. I usually do this by holding the bare wire between a pair of needle nose pliers and then rotating the wrist to make the hook shape in the wire. This hook will easily go around the screws on each side of the outlet and/or switch to make a secure connection when tightened.
Remember that all electrical work in a home is governed the “jurisdiction having authority.” Most jurisdictions follow the standards that are promulgated in the National Electrical Code, but have sometimes modified these standards in their local and state building codes. Many states and local jurisdictions permit homeowners to perform their own electrical work, but some do not. Consult your local laws, ordinances and local building codes before beginning any electrical work. In addition, be certain that you know what you are doing. If drywall is improperly hung, then you will just have an eyesore on your hands. If electrical work is improperly done, it can result in your house burning down or someone being electrocuted! When in doubt, don’t do it.
Other Electrical Articles