Home Improvement Skills & Specialties Electrical Wiring & Circuits

10 Different Types of Electrical Wire and How to Choose One

Untangle the different types of electrical wires so you can choose the right one

Various electrical wires

The Spruce / Margot Cavin

Electrical wire is typically made of copper or aluminum, and these conductive materials are insulated as wires that bring electricity to various parts of your home. When you're installing new wiring, choosing the right wire or cable is half the battle.

When examining the old wiring in your home, identifying the wire type can tell you a lot about the circuit the wiring belongs to (for example, if you open a junction box and need to determine which wires go where). Wiring for modern homes is quite standard, and most homes built after the mid-1960s have similar types of wiring.

Below, learn the different types of home electrical wires to choose the right option for completing electrical projects accurately and safely.

Tip

Once you identify your houses wiring type, don't try to imitate it before consulting your local building codes. Any new electrical installation requires new wiring that conforms to local building codes.

Wiring Terminology

It helps to understand a few basic terms used to describe wiring. An electrical wire is a type of ­conductor, which is a material that conducts electricity. In the case of household wiring, the conductor itself is usually copper or aluminum (or copper-sheathed aluminum) and is either a solid metal conductor or stranded wire.

Most wires in a home are insulated, meaning they are wrapped in a nonconductive plastic coating. One notable exception is ground wires, which are typically solid copper and are either insulated with green sheathing or uninsulated (bare).

Warning

Many larger wires in your home carry 120- to 240-volt circuit voltage, often referred to as line voltage, and they can be very dangerous to touch. Several wires in your home carry much lesser amounts of "low-voltage" current. These are less dangerous, and with some, the voltage carried is so low that there is virtually no chance of shock. However, until you know exactly what kind of wires you are dealing with, it's best to treat them all as dangerous.

  • 01 of 10

    NM Cable

    NM electrical cable

    The Spruce / Margot Cavin

    • Best for: Interior use in dry locations

    Often called “Romex” after one popular brand name, nonmetallic (NM) cable is a type of circuit wiring designed for interior use in dry locations. NM is the most common type of wiring in modern homes. It consists of two or more individual wires wrapped inside a protective plastic sheathing. NM cable usually contains one or more “hot” (current-carrying) wires, a neutral wire, and a ground wire.

    These conductors are insulated in white (usually neutral) and black (usually hot) for installation. Most NM cables have a flattened tubular shape and run invisibly through the walls, ceiling, and floor cavities of your homes.

    Tip

    As an alternative to NM cable, individual wires can be installed inside of a rigid or flexible metal or plastic tubing called conduit. Conduit is typically used where the wiring will be exposed and not hidden inside walls, floors, or ceilings.

    The most common sizes and their amperage (amp) ratings are:

    • 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)

    NM cables are color-coded to indicate the wire gauge:

    • White sheathing indicates NM cable with 14-gauge conductors.
    • Yellow sheathing indicates NM cable with 12-gauge conductors.
    • Orange sheathing indicates NM cable with 10-gauge conductors.
    • Black-sheathed cable is used for both 6- and 8-gauge wire.
    • Gray sheathing is not used for NM cable but is reserved for underground (UF) cable or service entrance cable (SE or SER).

    Warning

    NM cable is dangerous to handle while the circuit conductors are carrying voltage.

  • 02 of 10

    UF Cable

    UF electrical cable

    The Spruce / Margot Cavin

    • Best for: Underground wire for outdoor fixtures

    Underground Feeder (UF) is a type of nonmetallic cable designed for wet locations and direct burial in the ground. It is commonly used for supplying outdoor fixtures, such as lampposts. Like standard NM cable, UF contains insulated hot and neutral wires, plus a bare copper ground wire. But while sheathing on NM cable is a separate plastic wrap, UF cable sheathing is solid plastic that surrounds each wire.

    This type of electrical wire is also a bit more expensive than NM wire because of its durable insulation. UF cable is normally sold with gray outer sheathing.

    Warning

    UF cable is also used for major circuit wiring and can carry a dangerous amount of voltage when the circuits are turned on.

  • 03 of 10

    THHN/THWN Wire

    THHN electrical wire

    The Spruce / Margot Cavin

    • Best for: Wiring inside of conduit in exposed, often unfinished, areas of the home

    THHN and THWN are codes for the two most common types of insulated wire used inside conduit. Unlike NM cable, in which two or more individually insulated conductors (copper or aluminum) are bundled inside a plastic sheathing, THHN and THWN wires are single conductors, each with its color-coded insulation. Instead of being protected by NM cable sheathing, these wires are protected by tubular metal or plastic conduit.

    Conduit is often used in unfinished areas, such as basements and garages, and for short exposed runs inside the home, such as wiring connections for garbage disposers and hot water heaters. These wires typically have similar prices to NM wire (plus the cost of the conduit). The letters indicate specific properties of the wire insulation:

    • T: Thermoplastic
    • H: Heat-resistant; HH means highly heat-resistant
    • W: Rated for wet locations
    • N: Nylon-coated, for added protection

    THHN and THWN wires have colored sheathings that are generally used to identify their function in a circuit:

    • Hot wires: Black, red, orange
    • Neutral wires: White, brown
    • Ground wires: Green, yellow-green

    Warning

    THHN and THWN wires are circuit wires that should never be handled when the circuits are turned on.

  • 04 of 10

    Low-Voltage Wire

    Low voltage electrical wire

    The Spruce / Margot Cavin

    • Best for: Circuits requiring 50 volts or less

    Low-voltage wiring is used for circuits typically that require minimal voltage, such as landscape lighting wires, sprinkler system connections, bell wires (for doorbells), speaker system wires, thermostat wires, or anything else that requires 50 volts or less. Wire sizes range from about 22 gauge to 12 gauge, and these wires can be made of copper or aluminum.

    Low-voltage wires typically are insulated and may be contained in cable sheathing or combined in twisted pairs, similar to lamp cord wire. These are typically very small wires that are much different from standard circuit wiring, and their costs tend to be lower than other household wires.

    Serious shocks rarely occur with low-voltage wires, but it is still always best to turn off devices before working with them.

    Continue to 5 of 10 below
  • 05 of 10

    Phone and Data Wire

    Phone and data wires

    The Spruce / Margot Cavin

    • Best for: Landline telephones and internet hookups

    Telephone and data wiring are low-voltage wires used for landline phones and internet connections, typically made from copper. Telephone cables may contain four or eight wires, while ethernet cables (internet connection) consist of eight wires arranged in four twisted pairs.

    The most commonly used telephone and data wires are Cat 5 (category 5) cable and its more modern counterpart Cat 6, which can be used for both phone and data transmission and offer greater capacity and quality than standard phone wire. Like low-voltage wire, ethernet cables are often cheaper than other types of household wiring like NM or UF cables.

    Although data wiring does carry a small amount of voltage, anything under 30 volts is generally regarded as safe (a household circuit carries about 120 volts of power). However, there is always a danger of data wiring coming into contact with household wiring, so you should treat it with caution and avoid touching bare wires.

  • 06 of 10

    Coaxial Cable

    Coaxial electrical wire

    The Spruce / Margot Cavin

    • Best for: Data wiring

    Coaxial cable, or "co-ax," is used for connecting TVs to antenna, cable services, and satellite dishes. While still used today, it's beginning to grow less common thanks to the use of other forms of data wiring, such as HDMI, for television data transmission. The minuscule amount of voltage carried by coaxial cable signals makes it very unlikely to cause a shock of any type—provided the cables are not in contact with another source of current.

    Coaxial cable is a round, jacketed cable that features an inner conductor (usually copper) surrounded by a black or white tubular insulating layer, surrounded by a tubular conducting shield made of braided wire. It can be identified by the threaded connectors that are used to make unions and device hookups.

  • 07 of 10

    Speaker Wire

    Cable reel with speaker wire close up photo

    eugenesergeev / Getty Images

    Best for: Connecting audio interfaces and speakers

    Speaker wire is a simple two-conductor strand consisting of wires individually wrapped in plastic. Though connected, they can easily be separated by hand. There is no difference between the two wires electrically speaking, but one or both wires will often feature some type of marking to make them more easily traceable over a distance. This helps ensure proper polarity when wiring up speakers.

    When choosing speaker wire, consult the manufacturer's instructions closely. Many speaker manufacturers will specify choosing larger gauge wire if running longer distances of wire or wiring up higher-ohm systems.

  • 08 of 10

    Ribbon Cable

    Ribbon cable

    Panyawatt / Getty Images

    • Best for: Electronic devices with tight housings

    Ribbon cable is a type of wiring where each wire conductor is attached at its side, creating a flat ribbon-like wire. Much like "ribbon cable," its signature shape has earned names like "flat cable" and "multi-planar cable." The purpose of this arrangement is to maximize the potential number of wires while minimizing the footprint, which allows for many wires to fit in tight spaces.

    Ribbon cable is often used in things like appliances, computers, printers, and other electronic devices that need to move a significant amount of data within a tight housing. Flat connectors on each end allow the wire to connect at two points while taking up a minimal amount of space.

    Continue to 9 of 10 below
  • 09 of 10

    Armored Cable

    Armored cables

    OgnjenO / Getty Images

    • Best for: Exposed interior wiring locations

    Armored cable, which you may come across in an older home renovation, is a type of wiring that features a metal jacket around the wires to protect them from damage.

    Armored cable is often referred to as "BX cable," though this is technically a specific branding of armored cable. One of the purposes of armored cable's metal jacket is to eliminate the need for conduit, as the wire has its protective layer. This cuts both material costs and labor costs.

    Tip

    Though armored cable can be installed in an exposed manner without the use of conduit, many installers opt to use conduit anyway if the wire will be in plain view, as the conduit makes for a much neater visual than the loose armored cable.

    Armored cable is often chosen for installation in interior locations that are exposed, which would leave the wiring vulnerable to damage. In these spots, NM or THHN would require conduit, whereas armored cable can be installed as is. Additionally, the metal jacket itself is utilized as a ground.

  • 10 of 10

    Metal-Clad Cable

    Steel metal-clad conduit

    anakeseenadee / Getty Images

    • Best for: Exposed applications in commercial buildings or garages

    Metal-clad cables, or MC cables, are very similar to armored cables, yet with some key distinctions. Like armored cables, metal-clad cables feature metal sheathing that offers protection to the wiring, allowing it to be installed in areas where it may be vulnerable to damage.

    However, unlike armored cables, metal-clad cables feature a full-size designated ground wire, while armored cables rely on a combination of the metal jacket and a thin wire or strip for grounding.

    MC cables also feature plastic sheathing around the internal wires, while armored cable uses paper. MC cables can be used indoors and outdoors, but can only be used in damp or wet locations when fitted with an outer PVC jacket and properly installed with fittings rated for wet locations. When in doubt, consult your local building codes before installation.

Choosing a Type of Electrical Wire

Whether you're replacing old wiring in your home or adding new electrical wires, it's important to choose the right type.

Here are some things to consider:

  • Intended purpose: Always select an electrical wire that is specified for the purpose you intend to use it. For example, in wet locations outdoors, UF wire should always be chosen to ensure that your home's electrical system is protected from the elements.
  • Amperage and volts: The amperage and volts of each wire should also be considered, and wires should be matched to the correct needs of every electrical project. For example, small wiring that can handle low-voltage applications like landscape lighting isn't qualified to carry the load required for a water heater.

If you're unsure which type of electrical wire you need, it's helpful to consult a professional electrician before installing any sort of electrical lines in your home.

The Spruce uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Kuphaldt, Tony R. and John Haughery. Applied Industrial Electricity. Electrical Safety: How Much Electric Current is Harmful? Iowa State University, 2020.