The Basics of Residential Electrical Wiring

electricianMany residential electrical projects involve replacing light switches or wall outlets. Larger projects may include rewiring a room or adding additional fixtures.

The wiring and equipment belong to the power company up to the electric meter base, but then the homeowner takes over. Call Us Today for more details.

A breaker box distributes electricity to circuits that run throughout the house. Each circuit has a set amount of electricity that it can use, and if the branch circuit gets too busy, the breaker will trip.

The wiring in a residential electrical system provides the pathway for electricity to travel from the service panel to receptacles and light fixtures. It also powers a home’s appliances. Almost any wire can carry current, but certain types of wiring are better at conducting it.

Wiring types and sizes vary considerably. The size of a wire determines its capacity, which is measured in amperes (amps). The amount of current that moves past a point within a wire in one second is called its voltage. Larger voltages can be dangerous, so it’s important to understand what type of wiring is used in your home before touching it.

Most residential wiring is made from non-metallic, or NM, cable. It has a flexible plastic sheath that covers multiple wires. The sheath is typically printed with wire gauge and circuit information. It’s also often color-coded to aid in identification. In new construction, the cable is installed before walls are closed up. Older homes are likely to use metal-clad cables, commonly known as BX cables. It is more difficult to work with than NM cable, but it’s still a good option in unfinished basements or other areas where the cable may be exposed to physical damage.

In addition to determining what type of wire you’re working with, it’s helpful to know its purpose. Black or red wires are hot, carrying electrical current from the service panel to a device that uses electricity (a receptacle, switch, or lighting fixture). White wires are neutral and don’t carry any current. Bare or green wires are ground wires. They create a path for current to return to the service panel should there be a short circuit.

Residential electrical systems are designed and tested to ensure safe, reliable, and long-lasting performance. In addition to strict national standards, building inspectors enforce detailed local requirements.

Most DIY-minded homeowners don’t perform major electrical projects, but most of them do have basic maintenance needs that involve replacing light switches and outlets. This is a great time to learn about the different parts of a residential electrical system and how they work together.

Service Panel

The service panel (or breaker box) connects the external wires coming in from the street to the internal cables running throughout your home. It is usually located in the garage, basement, or utility room. Its large metal box with a hinged cover contains a series of switches called circuit breakers. These super-sensitive switches keep the wiring in your house safe and alert you when something is wrong.

There is a main switch that controls the power that is available from the electricity provider, and there are a bunch of smaller switches that each control a single area of your home’s wiring. Unlike the old plug fuses that used to be in the fuse panels, these circuit breakers are capable of shutting off individual areas of your home’s electrical system.

Each breaker has a label showing what it controls. A simple 15-amp breaker might control lighting or standard outlets, while higher-amperage breakers control high-use outlets like those in kitchens or garages, as well as major appliances such as refrigerators and clothes dryers. You can add more circuits to your panel as long as there are spaces, and you can even upgrade from a fuse panel if you need to increase the amount of electricity your house can draw.

Before you work on your electrical panel, be sure to turn off the power to the entire house at the meter using the disconnect switch. If you do not, there will still be electricity in the lines that connect to the hot bus bars, and a fault at any point along those lines could result in fire or injury.

In addition, be careful when working on the breaker panel with tools such as screwdrivers and pliers, since you may touch parts of the service wires and transmit an electric shock to yourself. If you do get shocked, you should immediately rinse your hands with water and then seek medical attention.

In some homes, you may also have a sub-panel, which is a separate breaker box that holds circuit breakers for an area of your house. These are often found in workshop areas, greenhouses, or other rooms that require their own dedicated circuits for powering specialized equipment.


A switch is an electrical device that lets you control a circuit by opening and closing its connection. It is commonly used to turn on and off lights in your home but can be utilized for other appliances as well. Electrical switches come in many styles—toggle, rocker, slider, push-button, etc.—but the style does not affect their function or wiring.

Single-pole switches are the most common light switches found in homes. They are easy to use and operate, and they attach to your home’s electrical wiring the same way. There are no neutral wires connected to these switches, so they are considered hot only when turned on. A green grounding screw is also found on most of these switches and is used for the circuit’s grounding wire.

Double-pole switches are larger and can handle more current than single-pole switches. They are often found in commercial settings where heavier equipment is used. A double-pole switch can shut off power to two powered conductors at once and is rated up to 30 amps.

Another common type of switch is a single-pole double throw (SPDT). This switch has one input and two different outputs, but only the COM terminal can be switched on or off. The other terminals are referred to as “traveler terminals” and are only active when the SPDT is in either the ON or the OFF position.

Lastly, you may find specialty switches that are more advanced than your standard switches. A timer switch, for example, will turn a light or appliance on at a certain time every day and then shut it off after a set amount of time to avoid wasted energy. A motion sensor switch, on the other hand, uses sensors to detect movement in a room and turns the lights on when you enter it and off after you leave.

Another new switch type is a smart switch, which pairs with your home Wi-Fi and allows you to control lights and other devices through an app on your phone or by using a voice assistant like Siri or Alexa. These switches can also be programmed to turn on or off at a specified time, making them an excellent choice for forgetful homeowners.


Power is fed into outlets, receptacles, or plug-in sockets throughout your home and then distributed to fixtures and appliances. You can find different outlet types that meet specific power requirements, and an electrician can help you determine what kind is right for your home.

The most common outlet in a home is a standard duplex, also known as a double wall outlet or a two-slot receptacle. These outlets typically have two vertical slots for electrical plugs and a third hole for a grounding pin. They deliver 120 volts, with one hot wire and one neutral wire carrying current to the outlet and back to your service panel.

Other types of residential outlets include 20-amp outlets, which look similar to standard outlets but have a slot design that looks like a sideways “T.” You’ll typically find these in higher-powered areas, such as kitchens, where you might use more powerful devices that can’t be run on a 15-amp outlet. You can also find outlets with USB ports, allowing you to charge your smartphones, tablets, and other devices without using an adapter.

Some outlets are tamper-resistant, with a built-in barrier that prevents objects other than plugs from being inserted. These outlets are usually marked as tamper-resistant, or TR, and they make it more difficult for children to get a hold of an outlet and cause a hazard. You might also have GFCI (ground fault circuit interrupter) outlets in kitchens and bathrooms. These outlets monitor the amount of current going through the outlet and disconnect it if there’s a large enough power surge to create danger.

All electrical outlets are regulated by your local codes and regulations to keep homes safe from fire hazards. These codes can vary from place to place, but most follow the recommendations of the national model code, the NEC. For example, the NEC states that in living areas, outlets should be spaced no more than six feet apart to avoid overstretching cords and associated safety risks. You can also find outlet types that offer more than just a power source, such as combination outlets, which allow you to plug in a switch along with a traditional pronged outlet.