Ultimate Guide to Home Wire Types
Becoming an electrician apprentice can take as little as 100 hours at a trade school up to a getting a four-year degree at a university. That should tell you how much training and knowledge is required to become a licensed electrician.
But understanding the basics of your home’s electrical wiring doesn’t have to be as intensive.
Plus, if you’re doing a simple DIY electrical project around the house, you need to know about your home’s different electrical wire types.
There’s also standard sizing, coding, labeling, and usage that you should understand.
Fortunately, we’ve broken down everything you need to know in this ultimate guide to home wire types.
Let’s get started.
Why do you need to know about your home’s electrical wiring?
If you’re doing any type of electrical project around the house, it would best if you knew a little about the wires you’ll encounter.
A little bit of electrical knowledge can enable you to work safely and efficiently. You’ll need to know about the different types of electrical wiring when you’re:
- Installing new wiring (you need to know what kind of wire to use)
- Troubleshooting electrical problems around the home (knowing the circuit that the wiring belongs to can help you determine the cause of the issue).
- Performing electrical repairs
Before we go any further, we should tell you that any changes that you make to your home’s electrical wiring must be up to code and comply with both the National Electrical Code and local ordinances.
Local ordinances tend to be more stringent and should be followed closely to prevent any errors.
If you fail to follow the required codes and ordinances, you increase the risk of hazards such as a fire.
Plus, if you ever decide to sell your home and an inspector catches it, you’ll likely have to spend more money to correct the issues than you would have had you done it right the first time and hired a professional electrician.
The Basics of Home Electrical Wire
Before we dive into the home electrical wiring types, there are some basic terms, coding, and labeling standards that you should know about.
If you understand these conventions mentioned above, you can ensure a much more comfortable trip to the hardware or electrical supply store.
Wire vs. Cable
Believe it or not, cable and wire aren’t the same things. Shocked? (see what we did there?)
Electrical wire is defined as “any material that conducts electricity.’ They’re the individual conductors in a jacket and can be either insulated or bare.
On the other hand, a cable is any combination of two or more wires and is assembled with a single jacket.
Color Coding for Cable Sheathing
The cable’s outer sheathing is color-coded to tell you about the size of the wires inside the cable.
The color code also indicates the cable’s amperage.
Here are typical colors and their associated size and amperage:
- Black. 8 or 6-gauge wire, 45 or 60 amp circuits
- Orange. 10-gauge wire, 30-amp circuit
- Yellow. 12-gauge wire, 20-amp circuit
- White. 14-gauge wire, 15-amp circuit
If you see a gray cable, that’s an underground feeder (UF) cable. All UF cables are gray. To know the UF wire’s gauge and circuit information, it’s necessary to check the cable-sheath label.
Cable-sheath color coding is a relatively new innovation. It wasn’t introduced to the electrical industry until 2001.
Companies aren’t even obligated to use it, so you should always check with the cable’s manufacturer to ensure that the color-coding complies with current standards.
Wire Color Coding
In contrast to cable-sheath color coding, color coding for wires is standard for all conductors. Wiring for houses is typically limited to the following colors:
- White – a neutral wire that completes a circuit by carrying the current back to the panel.
- Black/Red – hot wires that carry electrical current from a circuit breaker or panel to a device such as a receptacle, switch, light fixture, or appliance.
- Green/Bare – ground wires that create a path for electrical current to return to the breaker, blow a fuse, and cut off electricity in the event of a ground fault.
There are other wire colors, but these are those that you’ll most likely encounter in your home.
By knowing what each wire represents, you can better understand its role in the overall structure of your home’s electrical system.
In addition to color-coding on the sheath, both wires and cables use labeling to give you information about:
- Number of wires inside a cable
- Type of insulation
- Other ratings
These labels are printed either on the wire insulation or the outer sheathing of a cable.
When you hear the term “wire size,” it refers to the actual conductor’s diameter. Here’s what’s funny: The American Wire Gauge System, in a nutshell, says that the smaller the wire is, the larger the gauge.
It’s important to know that the size of the wires you choose must match the amperage of the circuit they’re being used in. If they don’t, you increase the risk of short-circuits and fires significantly.
The gauge of a wire is what determines how much current-carrying capacity it is.
What’s the current-carrying capacity?
Current-carrying capacity is the amount of amperage that a wire can handle safely.
Home electrical wire is typically 12 or 14-gauge unless you’re using it for appliances. In that case, you’ll be using 10, 8, or 6-gauge.
Appliances like stoves, dryers, water heaters, heaters, and air conditioning units require a larger gauge wire because they draw a higher amperage.
Stranded vs. Solid Wire
If you need to push the wire through a conduit, use a solid wire. On the contrary, if you need to pull wire through a conduit, you should consider using stranded wire. Because it is more flexible, stranded wire is easier to get around hard-to-reach areas and corners.
What are the Types of Electrical Wire in a Home?
There are several types of wires and cables found throughout and around your home.
Let’s go into more detail.
Non-Metallic (NM) Cable
If your home was built after around mid-1960, it likely has NM cable.
NM cable is the most common type of home electrical wiring. You’ve probably heard it referred to as Romex, which is actually a brand name for this electrical wire.
You know, kind of like here in South Louisiana, any weed trimmer is a “Weed Eater,” and any soft drink is a “Coke.”
But we digress back to NM cable.
NM cable typically has three or more individual conductors wrapped in a flexible plastic jacket (sheathing). There is usually a hot wire, a ground wire, and a neutral wire in one NM cable.
Non-metallic cable is used for interior home electrical wiring in dry environments. NM cable is typically used for appliances, junction boxes, light fixtures, and outlets, with the most common sizes of NM found in modern homes being:
- 14-gauge, 15-amp circuits
- 12-gauge, 20-amp circuits
- 10-gauge, 30-amp circuits
- 8-gauge, 40-amp circuits
- 6-gauge, 55-amp circuits
In some instances, your home’s electrical wires may be installed in a conduit, a flexible metal or plastic tubing, but this is usually in instances where your wiring is exposed.
NM Cable Regulations
Before we go on to the next type of wiring in your home, there are some regulations around NM cable that we feel like you should know.
First, NM cable cannot be used in residential construction exceeding three stories in height. Although strictly designed for homes, NM cable is prohibited from being used in commercial applications.
As with anything code-oriented, there are always variances and deviations allowed, so it’s best to check with your local building official if you have any questions.
Second, NM Cable is designed as a permanent home electrical wire system and shouldn’t be used as a substitute for extension cords, and definitely shouldn’t be used as wiring pigtails for your appliances.
Lastly, you must adequately support NM cables where necessary. The use of nails or staples is prohibited, and anything that could damage the cable is not permitted as support. Additionally, NM cable shall be secured at intervals that do not exceed 4.5 feet.
Like we mentioned before, local ordinances on house electrical wires tend to be more strict than national codes.
In some communities, NM (Romex) cable is not permitted. Instead, these locals require the use of armored cable (or AC).
Also known as BX, this type of electrical wiring has been in use since the early 1900s and is still in use today.
AC wiring has flexible metallic sheathing that provides extra protection to the conductors inside.
Like NM Cables, AC (BX) isn’t permitted for residential construction exceeding three stories or commercial buildings.
Rules and regulations regarding supporting armored cables are similar to non-armored ones, but, again, it’s best to consult with local building officials should you have any questions.
Underground Feeder Cable
Whereas armored (AC) and non-metallic (NM) cables are used in dry, interior conditions, underground feeder (UF) cable is designed for use outdoors or in wet conditions.
When you need to run wire for outdoor projects or underground, you’ll need to use UF cable, a non-metallic cable that can be buried underground without conduit and can get wet without any issues.
Just like NM cable, UF cable is made up of three wires:
- One hot wire
- One neutral wire
- One bare ground wire
Metal-clad cable is usually used when running wire through unfinished areas like a basement. Even though we don’t have too many basements here in South Louisiana, we’ll continue.
If your wiring is exposed and has a possibility of physical damage, you should use a metal-clad cable.
Low-voltage wiring is permitted on any circuit that uses less than 50 volts (items that don’t require a lot of electricity), such as:
- Landscape lighting
- Alarm systems
Low voltage wires range from 12 to 22-gauge and are typically insulated or covered in cable sheathing.
Phone and Data Wire
Both your phone (landline) and internet use low-voltage wires. Although your telephone and data cables may contain anywhere from four to eight wires, the most common cable type used for these purposes is Category 5 (Cat 5).
Cat 5 cables look like a large telephone cable (if you remember those) and consist of eight wires wrapped together in four pairs.
Your home’s electrical wire system is complicated. But, by now (hopefully), you have a greater understanding of its components and are more prepared to diagnose problems, complete repairs, and plan for renovations.
Now that you’ve read this ultimate guide to home electrical wires, we hope that you have a better grasp on:
- How size relates to amperage
- How cable-sheath and wire coding world
- How to read a cable or wire label
- The difference between wires and cables
- When to use solid wire vs. stranded wire
- How to select the correct wire your application
But don’t get ahead of yourself. Knowing and understanding your home’s electrical system doesn’t necessarily qualify you to repair or change it.
When it comes to your home’s electrical system, you’d be best suited to enlist the help of a professional.
For your safety and peace of mind
If you are in the Baton Rouge area and need to hire an electrical contractor, we’re here to help. View our wide range of electrical services, or contact us today to see how we can take care of your electrical work for you.