Residential Electrical Circuit

A residential electrical circuit is a loop of power wires that delivers electricity to outlets, switches and devices. Each circuit is sized to safely carry the amount of current it sends to appliances.

The breaker or fuse in the service panel protects each circuit against overload. If too much current flows through the wires, the breaker or fuse "trips" and must be reset.

Electrical Cable

Electrical wire is the main way power gets to your home. It’s important to have Nashville Electrician because they are  committed to resolving your electrical issues in a timely and dependable way. It is essential to entrust electrical work to certified specialists.

Electrical cables are made from a group of insulated wires twisted together or braided. The conductors are usually copper. They can be bare or coated with another metal such as tin, gold or silver to make them easier to work with and to offer better between-strand lubrication. In addition to the copper wires, a cable might also include a nonmetallic jacket that protects against moisture, oil corrosion and fungus.

A common configuration in homes is parallel wiring in which the hot and neutral wires are routed through junction boxes in which individual receptacles, switches and devices are branched off. This allows you to have multiple lighting sets and other equipment running on the same circuit, but with two separate fused circuit breakers in case one of them burns out.

More demanding appliances such as ranges, clothes dryers, water heaters and central air conditioning require dedicated circuits that are a different voltage than the rest of the system. Dedicated circuits typically have two hot wires and one neutral. They may be hung overhead (a service drop) or brought in through the walls (a service lateral). The voltage in these wires depends on what equipment they supply, but will always be lower than 120-volt household circuits.

Service Panel

Electrical current to your home runs through a service panel, or breaker box. It starts at a power plant, travels over long distances in those tall wires you see on the poles, passes through local transformers (the big cans that are often found on utility poles) that step down the voltage, then enters your home through the service drop and goes into the breaker panel.

The breaker panel contains the main fuses or circuit breakers that power different parts of your house. It also has a main switch above the columns of breakers that you can use to cut all power to the house.

Power leaves your home's breaker panel through one or more hot wires, which are covered in black insulation. It returns to the breaker panel through a neutral wire, which is either bare or with white insulation. The neutral and ground wires connect to a bus bar inside the breaker panel.

Inside the breaker panel, the single-pole breakers that control lighting circuits are rated at 15 or 20 amps; the double-pole breakers that run appliances like stoves and clothes dryers are rated at 40 amps. A residential electrical circuit is designed so that the total amount of electricity used will never exceed these ratings; if it does, the breakers will trip. There are a number of things that can cause an overload: too many appliances connected to the same circuit, a defective appliance or wiring, or even just adding more lighting to the house.

Branch Circuits

A branch circuit is a wire that runs from the final overcurrent protection device (usually a breaker or fuse) to devices such as light fixtures and outlets. Each circuit is rated for a certain amount of current, or amperes (amps). If the load on the wires exceeds the amperage limit, the breaker will open and shut off the flow of electricity. This prevents the wiring from melting or catching fire.

The number of wires in a circuit depends on the type of equipment it supplies. General-purpose circuits typically have two hot wires and one neutral. These usually supply lights and outlets for appliances such as refrigerators, freezers and dishwashers. The National Electrical Code (NEC) requires that each branch circuit have a grounding wire.

Dedicated appliance circuits have an unbroken, non-shared wiring run to individual pieces of equipment such as electric ranges and clothes dryers. These may be 120-volt or 240-volt circuits and have cables that include three wires — two hot and one neutral.

Room circuits divide the flow of power into rooms in a home or apartment building. If there is a problem with one of these circuits, it's easier to identify where the issue is located because only that area's lighting and outlet devices are affected. Room circuits are typically 120-volt and have a maximum current carrying capacity of 15 or 20 amps. A 240-volt circuit can carry 30 or 40 amps.


An outlet (also called a socket, plug or wall plug) acts as a bridge between electrical equipment and the electricity supply. It’s a female end that houses the prongs of a male connector. Plugging in a cord end completes the circuit and allows power to flow through it. It’s important to understand how outlets work so that you can safely do electrical wiring repairs around the house.

Residential electrical circuits are designed with safety in mind. Circuit breakers replace older fuses in most modern homes and provide superior protection from electrical fires and shock. These devices can be reset to restore power, and they’re more reliable than fuses because they trip off instead of popping like a fuse in a fire.

A household outlet receptacle is usually located in the wall and has two brass screw terminals, one for incoming power, the other for outgoing power. It also has a grounding wire that’s bare or covered in green insulation and is intended to prevent shock by diverting any stray currents to the ground. Most modern wiring uses GFCI and AFCI receptacles that are more reliable and provide extra protection against shock by tripping in the event of an overload or other fault. However, you can still see the traditional wiring in many homes. These receptacles are connected to the breaker or junction box with a single wire or pair of wires that run all the way to the first wall outlet.


Switches control current to outlets and other devices throughout the house. Each circuit has a return path that leads back to the service panel through a neutral conductor. The grounding wire is bare or covered in green insulation and helps prevent shock by diverting any stray electricity to the ground.

Residential electrical wiring usually connects to switches in a large metal box with a hinged cover called the breaker panel (or fuse box in older homes). There is one switch that can shut down all of the electricity from the service line. Other switches, called circuit breakers, control each individual electrical circuit.

Most switches are single-pole, double-throw (SPST), which means they have two terminals that can be connected or disconnected. But there are other types of switches, such as a three-way switch or a four-pole, double-throw switch (SPDT).

Some appliances, like water heaters and furnaces, require dedicated circuits with separate hot and neutral conductors. These circuits are typically 240-volt circuits, and the cable is thicker and more durable than smaller wires in a home.

When a switch is closed, the contacts are under their greatest stress as they go from infinite resistance to almost zero. During this transition, electricity is converted to heat. If the contacts remain hot, they may burn or weld themselves closed. To prevent this, a switch should have an insulated handle to avoid contact with the metal.


The devices that get power from the branch circuits are what we typically call "home wiring". These include receptacle outlets, light fixtures, switches and appliances.

Modern home wiring is usually a single cable with two or more insulated, solid copper wires plus a bare grounding wire. The "hot" leg, typically covered with black insulation, carries electricity from the main service panel to light bulbs and receptacle outlets. The "neutral" leg is usually covered with white insulation and returns energy to the service panel.

There are three principle topologies for residential electrical circuits, depending on the needs of your household. One type is a series circuit, in which all the devices along the circuit are connected in a continuous row. If any of the devices on this circuit fail or are disconnected, all the other devices will stop working.

A second type of residential electrical circuit is a parallel circuit. This is more common for appliance circuits, in which each device gets its own dedicated circuit. This may be a 120-volt circuit that powers toasters and hair dryers or a 240-volt circuit that supplies large appliances like washers, dryers and stoves.

Dedicated circuits usually have their own breakers or fuses in the service panel, but they can also be connected to one or more breaker panels. This allows a homeowner to shut off power to most or all of the homes' circuits with just one trip to the main panel, instead of having to visit individual breaker panels.

A residential electrical circuit is a loop of power wires that delivers electricity to outlets, switches and devices. Each circuit is sized to safely carry the amount of current it sends to appliances. The breaker or fuse in the service panel protects each circuit against overload. If too much current flows through the wires, the…