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Types Of Home Wiring

home wiring
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You probably know that you need certain wires to provide power to different appliances, but you might not know just how complicated your home wiring system is. Art Plumbing, Air Conditioning & Electric is here to explain the basics of home wiring by looking at the different types, sizes and colors of electrical wires.

Electrical Wiring: The Basics

In order to understand the different types of wiring systems in your home, it is important to first know the basics of electrical wiring. An electrical wire is made up of a material that is able to conduct electricity, known simply as a conductor. In home wiring systems the conductor is either one thick strand of aluminum or copper, or it can be multiple stands of conducting material grouped together to form one single wire.

To prevent wires from shocking us, they are insulated in a non-conductive plastic coating. Wires that are covered in black or red coating are considered ‘hot’ wires, and should not be touched. Neutral wires should only be coated in white plastic, and can technically be touched, but it is best to avoid touching any wires that appear red, black or white. The only wires that are truly safe to touch are known as ground wires, and are made of a single piece of copper that either remains bare or is coated in green plastic. Ground wires do not form part of electric circuits (they don’t carry electricity), but are instead used as fail-safe if something goes wrong with a hot wire.

What Wires Are Used In Your Home?

The wires that you might come across in your home really depend on how long ago your home was built, or how recently you have updated your wiring systems.

    • NM Wire

      If your home was built in the last 50 years, it’s likely covered in non-metallic sheathed cable, commonly known as NM wire or Romex (named after the popular NM wire brand). Inside NM cables you will find three (or more) wires of different colors. The cables themselves are covered in non-conductive and heat resistant thermoplastic sheathing. Standard NM wiring is used for dry locations, so definitely should not be found outdoors. Although it is almost always found behind drywall or inside other materials, if you do come across any yellow, white or orange wires it is most likely standard, indoor NM wire.

      The most common size (gauge) and amperage for NM wires are:

      • 14-gauge, with 15-am circuit
      • 12-guage, with 20-am circuit
      • 10-gauge, with 30-amp circuit
      • 8-gauge, with 40-amp circuit
      • 6-guage, with 55-amp circuit
  • UF Cable

    UF cable stands for underground feeder cable, and is a type of wiring that can be used outside or in wet locations. It is usually grey, and looks similar to NM cables. UF cable is a type of direct burial cable, and is often used to power outside lamp posts or detached garages. Unlike NM cable, UF cable is covered in solid plastic that completely surrounds each individual wire.

  • THHN/THWN Wire

    Wires are cleverly labeled to indicate what type of insulating sheath covers the individual conductors.

    • Wires stamped with a ‘T’ are thermoplastic, fire-resistant cables.
    • A single ‘H’ means that the wire is heat-resistant up to temperatures of 167°F.
    • ‘HH’ means that the wire can withstand temperatures of up to 194°F.
    • Wires with a ‘W’ can be used in wet locations.
    • An ‘X’ indicates that a wire is made from a flame-retardant synthetic polymer.
    • Wires stamped with an ‘N’ are oil and gasoline resistant due to a nylon coating.

    The most common wires found in house are thermoplastic high heat-resistant nylon coated wire (THHN) and thermoplastic heat- and moisture-resistant nylon coated wire (THWN). These wires are often installed in something called a conduit, which can be either a rigid or a flexible plastic or metal tubing, typically not hidden behind walls.

Although it may be tempting to buy some wires from Walmart or your local Home Depot and try fix your electrical wiring issues yourself, it is always best to call Art Plumbing, Air Conditioning & Electric for wiring assistance. Electrical wiring is complicated, and potentially dangerous. Don’t risk your safety by DIYing with electricity!


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