Home Wiring 101 – Basic Electrical Wiring for Homeowners
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.
Standard household electrical wire contains three wires: black (hot), white (neutral) and bare copper (ground).
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.
Use wire-stripping pliers to shear the insulation from the ends of the wires. The strippers can accommodate various wire gauges to ensure the plastic is stripped without damaging the wire.A simple volt detector is an inexpensive tool that can detect live wires to ensure the power is disconnected before you work on electrical wires.
First and foremost, always disconnect the electrical power supply before working with any part of the electrical system.
Wires are generally connected with wire nuts, which are categorized by gauge to match the electrical wires.
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.
When connecting an electrical fixture, connect the wiring by matching the color-coded wires of the supply line and fixture, twisting them together, and then capping each connection with a wire nut. Many light fixtures don’t have black and white wires, in which case, look for a rib on the wire sheathing to determine the neutral wire.
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.
The electrical current carried by the wire can be interrupted with the switch, which simply breaks the connection between the two hot wires.A single-pole light switch has two brass screws on one side for connecting the black wires.
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 (plugs or outlets) are connected in a row, so-to-speak, by attaching the white wires to the silver/stainless metal screws on one side, and connecting the black wires to the brass screws on the other side. The ground wire connects to the green screw at the bottom. Unlike a light fixture, wall outlets remain “hot,” meaning that they always have live electrical current in them, all of the time.
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.
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Electrical Basics 101
People depend on electricity constantly, and when the power goes out in a storm or there’s a tripped breaker or another problem in an electrical circuit, understanding the basic components of an electrical system can help you get things running again. It’s also important to know who is responsible for what portion of your electrical service. The utility company handles the line portion of your service, which includes everything up to the attachment point on your house. From there, it’s called the load side, and everything on the load side is your responsibility.
Electrical Service Connection and Meter
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Your home’s electricity starts with the power service and electric meter. The utility company’s service cables (whether overhead or underground) extend to your house and connect to the utility’s meter base. The electric meter plugs into this meter base. The meter measures the amount of electricity your home uses and is the basis for the charges on your electric bill. The meter runs only when electricity is used in the house.
Some home electrical systems include a dedicated disconnect switch that is mounted on an outside wall of the home near the electric meter. In the event of a fire or flash flood, or if work needs to be done on the system, a disconnect switch allows you to shut off the power from outside the home so you don’t have to enter the home to turn off the power. If an electrical system does not include a separate disconnect switch (and most do not), the main circuit breaker in the home’s main service panel (breaker box) serves as the system disconnect.
Main Service Panel
After passing through the meter, your electrical service feeds into your home’s main service panel, commonly known as the breaker box. Two large “hot” wires connect to big screw terminals, called lugs, inside the service panel, providing all the power to the panel. A third service wire, the neutral, connects to the neutral bus bar inside the panel. In simple terms, electricity is supplied to the house on the hot wires. After it flows through the household system, it is fed back to the utility on the neutral wire, completing the electrical circuit.
Main Circuit Breaker
The service panel contains a large main breaker that is the switch controlling the power to the rest of the circuit breakers inside the panel. It is sized according to your home’s service capacity. A standard panel today provides 200-amp (ampere) service. Older panels were sized for 150, 100, or fewer amps (amperes).
A main breaker of 200 amps will allow a maximum of 200 amps to flow through it without tripping. In a tripped state, no current will flow to the panel. In systems without an external disconnect switch, the main breaker serves as the household disconnect.
Turning off the main breaker stops the flow of power to all of the branch circuit breakers in the panel, and therefore to all of the circuits in the house. However, power is always flowing into the panel and to the service lugs even when the main breaker is shut off unless the power is shut off at a separate disconnect switch. Power is always present in the utility service lines and the electric meter unless it is shut off by the utility.
Branch Circuit Breakers
The breakers for the branch circuits fill the panel (usually below) the main breaker. Each of these breakers is a switch that controls the flow of electricity to a branch circuit in the house. Turning off a breaker shuts off the power to all of the devices and appliances on that circuit. If a circuit has a problem, such as an overload or a fault, the breaker automatically trips itself off.
The most common cause of a tripped breaker is a circuit overload. If you’re running a high-demand appliance, such as a vacuum, toaster, or heater, and the power goes out, you’ve probably overloaded the circuit. Move the appliance to a different circuit and reset the breaker by switching it to the ON position. If the breaker trips again—without the appliance plugged in—you must call an electrician. There may be a dangerous fault situation in the circuit.
Devices are all the things in the house that are connected to electricity, including switches, receptacles (outlets), light fixtures, and appliances. Devices are connected to the individual branch circuits that start at the breakers in the main service panel.
A single circuit may contain multiple switches, receptacles, fixtures, and other devices, or it may serve only a single appliance or receptacle. The latter is called a dedicated circuit. These are used for critical-use appliances, such as refrigerators, furnaces, and water heaters. Other appliances, such as dishwashers and microwaves, usually are on dedicated circuits, too, so that they can be shut off at the service panel without interrupting service to other devices. This also reduces the incidence of overloaded circuits.
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Switches are the devices that turn on and off lights and fans in your home. They come in many different styles and colors to suit your design needs. There are single-pole, three-way, four-way, and dimmer switches. When you flip a switch off, it “opens” the circuit, meaning the circuit is broken or not complete and the power is interrupted. When the switch is on, the circuit is “closed,” and power flows beyond the switch to the light or another device it is controlling.
Electrical outlets, technically called receptacles, provide power to plug-in devices and appliances. Televisions, lights, computers, freezers, vacuums, and toasters are all good examples of devices that can be plugged into an outlet. Standard outlets in a home are either 15-amp or 20-amp; 20-amp outlets can provide more electricity without tripping a breaker. Special outlets for high-demand appliances, such as electric ranges and clothes dryers, may provide 30 to 50 or more amps of power.
In potentially wet areas of a home, such as bathrooms, kitchens, and laundry rooms, some or all of the outlets must have GFCI (ground-fault circuit-interrupter) protection, provided by GFCI outlets or a GFCI breaker.
Your home’s wiring consists of a few different types of wiring, including non-metallic cable (commonly called Romex), Bx cable, and wiring concealed in conduit. NM cable is the most common type of circuit wiring. It is suitable for use in dry, protected areas (inside stud walls, on the sides of joists, etc.) that are not subject to mechanical damage or excessive heat.
Bx cable, also known as armored cable, consists of wires running inside a flexible aluminum or steel sheath that is somewhat resistant to damage. It is commonly used where wiring for appliances, such as dishwashers and garbage disposals, is exposed.
Conduit is a rigid metal or plastic tubing that protects individual insulated wires. It is used in garages, sheds, and outdoor applications where the wiring must be protected from exposure.
Wires running inside NM cable, Bx cable, or conduit are sized according to each circuit’s amperage. Wire size is given in its gauge number. The lower the gauge, the larger the wire, and the more current it can handle. For example, wiring for 20-amp circuits is 12-gauge, which is heavier than the 14-gauge wiring used for 15-amp circuits.
basics for beginner electricians, current and voltage, how to calculate
If an electrical unit fails, the right decision would be to call a specialist who will quickly fix the problem.
- Types of circuits, voltage and current
- Variable and constant
- Power and other parameters
- Ohm’s Law
If this is not possible, lessons for electricians will help you fix this or that breakdown yourself.
When doing this, it is worth remembering the safety precautions in order to avoid serious injury.
Safety rules must be learned by heart – this will save health and life when troubleshooting electrical problems. Here are the most important electrical basics for beginners:
- The first electrical work is best done under the supervision of an experienced electrician.
- It is not recommended to work with high voltage alone. There should always be someone nearby who will insure in case of problems – de-energize the network, call emergency services and provide first aid.
- All work must be carried out with de-energized networks. You also need to make sure that no one connects the electricity during installation.
To perform installation work, you must purchase a sensor (phase indicator), similar to a screwdriver or an awl. This device allows you to find a wire that is energized – when it is detected, an indicator lights up on the sensor. The devices work differently, for example, when the corresponding contact is pressed with a finger.
Before starting work, you must use the indicator to make sure that all wires are not de-energized.
The fact is that sometimes the wiring is laid incorrectly – the machine at the entrance turns off only one wire, without de-energizing the entire network. Such a mistake can lead to sad consequences, because a person hopes for a complete shutdown of the system, while some area may still be active.
Types of circuits, voltage and current
Electric circuits can be connected in parallel or in series. In the first case, the electric current is distributed over all circuits that are connected in parallel. It turns out that the total unit will be equal to the sum of the current in any of the circuits.
Parallel connections have the same voltage. In a series combination, current flows from one system to another. As a result, the same current flows in each line.
It makes no sense to dwell on the technical definitions of voltage and current (A). It will be much clearer to explain with examples. So, the first parameter affects how well you need to isolate different areas. The larger it is, the higher the probability that a breakdown will occur in some place. From this it follows that high voltage requires quality insulation . Bare connections must be kept away from each other, from other materials and from the ground.
Electrical voltage (U) is usually measured in Volts.
Higher voltage is more life-threatening. But do not assume that low is absolutely safe. The danger to a person also depends on the strength of the current that passes through the body. And this parameter is already directly subordinate to resistance and voltage. At the same time, the resistance of the body is associated with the resistance of the skin, which can vary depending on the moral and physical condition of the person, humidity and many other factors. There have been cases when a person died from an electric shock of only 12 volts.
In addition, different wires are selected depending on the current strength. The higher A, the thicker the wire needed.
Variable and constant
When electricity was in its infancy, direct current was supplied to consumers. However, it turned out that the standard value of 220 volts is almost impossible to transmit over a long distance.
On the other hand, thousands of volts cannot be connected – firstly, it is dangerous, and secondly, it is difficult and expensive to manufacture devices operating at such a high voltage. As a result, it was decided to convert the voltage – 10 volts reach the city, and 220 already gets into the houses. The conversion takes place using transformer .
As for the voltage frequency, it is 50 Hertz. This means that the voltage changes its state 50 times per minute. It starts from zero and rises to 310 volts, then drops to zero, then to -310 volts and rises to zero again. All work proceeds in a cyclic way. In such cases, the voltage in the network is 220 volts – why not 310, will be discussed further. Abroad, there are different parameters – 220, 127 and 110 volts, and the frequency can be 60 hertz.
Power and other parameters
Electrical current is needed to perform some work, such as turning a motor or heating batteries. You can calculate how much work it will do by multiplying the current by the voltage. For example, an electric heater that has 220 volts and has a power of 2.2 kW will draw a current of 10 A.
Standard power measurement is in watts (W). An electric current of 1 ampere with a voltage of 1 volt can produce 1 watt of power.
The above formula applies to both types of current. However, the calculation of the first has some complexity – it is necessary to multiply the current strength by U in each unit of time. And if we take into account that the voltage and power indicators of alternating current change all the time, then we will have to take the integral. Therefore, the concept effective value was applied.
Roughly speaking, the effective parameter is the average value of current and voltage, chosen in a special way.
Alternating and direct current has an amplitude and effective state. The amplitude parameter is the maximum unit to which the voltage can rise. For a variable type, the amplitude number is equal to the current multiplied by √ 2. This explains the voltage indicators of 310 and 220 V.
The next concept in the basics of electricians for beginners is Ohm’s law. He states that current is equal to voltage divided by resistance. This law applies to both AC and DC.
Resistance is measured in ohms. So, through a conductor with a resistance of 1 ohm at a voltage of 1 volt, a current of 1 ampere passes. Ohm’s law gives rise to two interesting consequences:
- If the A flowing through the system and the resistance of the circuit are known, then the power can be calculated.
- Power can also be calculated knowing the effective resistance and U.
In this case, not the mains voltage, but U applied to the conductor is taken to determine the power. It turns out that if any device is connected to the system through an extension cord, then the action will be applied both to the device and to the wires of the extension device. As a result, the wires will heat up.
Of course, it is undesirable for the connections to heat up, since this leads to various malfunctions of the electrical wiring.
However, the main problems are not in the wire itself, but in the various connection points. At these points, the resistance is ten times higher than along the perimeter of the wire. Over time, as a result of oxidation, the resistance can only increase.
Particularly dangerous are the junctions of different metals. In them, the oxidation processes are much faster. Most common connection areas:
- Twisted wires.
- Terminals for switches, sockets.
- Screw terminals.
- Contacts in switchboards.
- Plugs and sockets.
Therefore, the first thing to do when repairing is to pay attention to these areas. They must be accessible for installation and control.
By following the above rules, you can independently solve some household issues related to the electrics in the house. The main thing is to remember safety precautions.
Electrics for kettles – instruction .
In-depth knowledge in this case is not required – this is part of the professionals, but everyone can replace the socket or switch on their own, assemble an extension cord with the necessary parameters.
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What is electric current and how does it ensure the operation of electrical appliances?
Electric current is an ordered movement of charged particles – electrons. In household networks, alternating current is used, the polarity of which is constantly changing, as a rule, with a frequency of 50 Hertz. That is, in one second, the polarity on the phase wire will change 50 times. To ensure the operation of an electrical appliance, only one phase – a wire that is energized from the mains supply, is not enough. We also need zero – working grounding. An electrical appliance operating on alternating current has two input contacts, and it does not matter which of them will go to the phase and which will go to zero. It is important that the circuit closes, the charged particles move into the heart of the equipment and make it work.
In the picture above, you can see that there are not two, but three insulated cores in the supply wire. Zero protective wire is a grounding that is necessary to remove static charge from the housings of household electrical appliances, which makes their operation more reliable and safe. It is important to follow the order of connecting wires when installing consumption points – sockets. In the photo below you can see how the power wires should be wired.
Moreover, you can swap the phase with zero, but the ground must be in its place.
Important to remember!
Phase wire – always red, brown or white. The zero wire is blue. Ground wire – yellow-green. These rules facilitate wiring and avoid short circuits during operation.
If you need to determine the phase in the socket, then you can do this with a tester screwdriver. To do this, take it by the plastic handle, hold the metal bolt on the end with one finger, and then touch the contact with the tip. If the red light in the screwdriver body lights up, then you are dealing with a phase. If it does not light up, then it is zero. It happens that the light bulb glows, but very weakly. This may indicate a wiring or electrical fault.
Such testing is absolutely safe.
The main elements of power supply in a private house
The supply cable to the house is supplied from a transformer, an example of which you see in the photo below.
It steps down the high voltage to the standard 220-230V that all household appliances are designed to handle.
A whole set of elements is used to distribute power around the apartment, including:
- Electricity meter
- RCD complex – residual current circuit breakers
The picture above clearly shows that a separate branch with RCD is allocated for each separate group of connection points or a power appliance.