What is a Residential Electrical Circuit?
A residential electrical circuit is a series of wires that runs to your home's switches, receptacles and outlets. It is important to have a thorough understanding of how house electrical circuits work.
Power enters your home through service lines, passes through the meter, then flows to the main panel, typically located in a utility space or garage. Each circuit has a hot wire (with black or red insulation), a neutral wire (white) and a bare ground wire.
Electrical Cable
The residential electrical wiring system of any house includes wires that power appliances and devices. These electrical circuits create a circular journey, going from the main panel to lighting fixtures, receptacles and other fixtures in a home, then back to the panel. Residential circuits also include a ground that diverts electricity away from hot wires and to the earth, which helps prevent electric shock. The thicker a cable's insulation, the more current it can safely carry, but any amount of current that passes through too many wires in quick succession can cause them to overheat and fail, potentially leading to an electrical fire or shock. To protect against this, a circuit must be equipped with either a fuse or breaker.
A fuse or breaker shuts off the flow of electricity in the event that a wire becomes overheated, and it must be replaced. Fuse or breaker boxes typically include two to six fuses or circuit breakers for each of the various circuits of a house, and these should be labeled so homeowners can identify them in an emergency.
Most homes are built with a main electrical panel that sits right next to or under the power meter. From there, the wiring of a house is divided into branch circuits that feed electricity to wall receptacles, switches and installed fixtures. There are 120-volt branch circuits for common outlets, and 240-volt circuits for large appliances.
When working with electrical wiring, homeowners should never touch any wires when a circuit is active. The electrical current that runs through the wires has enough force to injure or kill a person, and it should only be handled by P2 Electrical Contracting who know what they are doing. The color-coded labels on the outside of a wire's sheath tell the gauge of the wire and the number and type of circuits it carries. For example, a wire labeled 14-2 has two 14-gauge copper conductors and a bare copper ground.
The older standardized electrical wiring method used in homes prior to the 1930s is known as knob and tube (K&T). This system uses single conductors that run through protective channels in joists and walls, with ceramic knobs that hold them in place and allow air to circulate around them. This allowed smaller and less expensive wires to be used, but it also left them susceptible to serious injuries if someone hammered a nail into both conductors simultaneously.
MC Cable
The electrical circuits in your house are designed to provide the power needed to operate household appliances and fixtures. They are controlled by switches and breaker panels, which help control when electricity flows to devices. They can also be monitored by a home energy management system.
An electrical circuit is a loop that begins with the service panel or power source and goes through wires, lighting fixtures, receptacles and switches before returning to the panel. A meter is often installed to record how much electricity is used, and you will be charged based on these kilowatt-hours.
Wires in the house are rated by their voltage (to neutral), surface temperature and conductor size, and they can only safely carry a certain amount of current. A cable’s conductors are insulated, and the sheath protects them from moisture, oil, chemicals and other contaminants. Each conductor has a color-coded sheath that indicates its purpose and what type of wire it is.
MC cables, also known as metal-clad cable or armored cable, feature a flexible metal sheath with an electromagnetic interference shield, which helps to prevent damage from lightning strikes and other sources of interference. These cables are available in several different sizes, and some of them have an integral grounding conductor that eliminates the need for a separate grounding wire. Type MC cables can be used in exposed or concealed work and are suitable for use with conduit or raceways.
In addition to MC cable, homeowners can also choose from a number of other types of residential wiring. One option is NM-B, which has two conductors and a grounding wire and is commonly called Romex. It’s usually used for general lighting and receptacle circuits up to 15 amps. Another choice is NM-B-WI, which has three conductors and is suitable for use in branch circuits, three-way switches and receptacles with three-way switches.
Other types of wire include service-entrance wire, which is used to bring utility wires into the home from the meter or breaker panel. It has a flame-retardant, moisture-resistant covering and may be copper or aluminum. It’s typically used to connect the meter and breaker panel to the main service lines that feed the house, as per Article 230 of the National Electric Code.
Stranded Wire
A stranded wire consists of many thin copper strands that are grouped and connected with non-conductive insulation. This makes them more flexible, malleable and delicate compared to solid wires. They are mostly used in places that require constant movement and bends like the door of your car or the robot arm of an industrial machine. This type of wire is also better suited for indoor applications.
The residential electrical system in a house carries 120 or 240-volt power through a series of branch circuits that connect to wall outlets, switches and installed fixtures such as ceiling lights and fans. Most of these are dedicated circuits that run to appliances and equipment such as dishwashers, clothes dryers and water heaters. They're protected from over-current through a breaker or fuse located in the main service panel of the home.
A single, vinyl-jacketed electrical cable contains two or more insulated, solid-copper wires and a bare copper grounding wire. One of the wires, called the "hot" leg, is covered in black insulation and carries electricity from the main service panel to the outlets and fixtures. The other wire, called the "neutral" leg, is covered in white insulation and returns the electricity to the panel.
Each wire in a residential electrical circuit is assigned its own voltage and current capacity, which is measured by the wire's gauge number or AWG (American Wire Gauge). The higher the AWG number, the thicker the wire and the more current it can safely carry.
When a wire is running in close proximity to another, its gauge number must match the other's to prevent the wires from touching and creating an electric shock. The AWG number is also used to indicate the wire's thickness, which affects its flexibility and its ability to resist damage caused by abrasions, cuts, and heat.
Stranded and solid wires both have their advantages, but stranded wire is preferred for most applications. This is because it is more flexible and can fit into tight spaces where solid wires would be difficult to install. It can also handle a much greater degree of flexing than solid wire without breaking, which is important in areas where the wires will be moving frequently or being pulled and pushed through conduit.
Solid Wire
Electricity has become a vital part of our lives, powering lights, appliances and maintaining comfortable temperatures throughout our homes. But electricity is not without its hazards, and it’s important to understand the basics of residential electrical wiring and circuits so you can protect yourself from shock and injury.
The residential electrical system starts with main service wires that enter the house from overhead power lines or underground feeder wires and connect to a service panel, usually located in a utility space or garage. From there, a series of branch circuits run to lights, receptacles and other devices throughout the home.
Dedicated circuits run to individual appliances or pieces of equipment, such as ranges, dryers, water heaters and central air-conditioners. These circuits are 240-volt and have two hot wires, one neutral and a grounding wire. They also require larger gauges of wire: 12- and 14-AWG (the lower the number, the larger the wire).
Most electrical systems use a black, red and white color code to identify the different circuits. The bare grounding wire, which is usually covered in green insulation, is there to help prevent electrical shock by diverting any short circuits that may occur to the ground, rather than through a switch, breaker or fuse.
The main panel is the distribution point for all the electrical circuits in a house, typically connected to a meter base that records how much energy you’re using. The meter is monitored by your electric utility company to ensure you’re not getting more or less than you’re paying for, which is the basis of how you get billed.
In the service panel, the energized power is distributed to the various circuits by strips of metal called hot bus bars. Each bus bar connects to a breaker or fuse, and the breaker or fuse controls how much current is sent to a room, outlet or device.
The stranded and solid wires all carry the same amount of voltage, but the difference is how they’re used in the home. Unlike stranded, which is multi-stranded with each strand twisted to form groups, solid wire has a single, solid conductor inside the insulation and is thicker and heavier than stranded. It has less current capacity but offers better connections and less resistance than stranded.
A residential electrical circuit is a series of wires that runs to your home's switches, receptacles and outlets. It is important to have a thorough understanding of how house electrical circuits work. Power enters your home through service lines, passes through the meter, then flows to the main panel, typically located in a utility space…