Electrical wire and cable must be sized and installed correctly to pass an electrical inspection and keep electricity running safely through your home. This guide will teach you the difference between types of electrical wires and types of electrical cables. You’ll also learn how to choose between electrical cables and wires for your projects.
Safety Tip: The National Electrical Code (NEC) and local building codes regulate the types of electrical wires and cable that can be installed in specific electrical applications.
While the terms wire and cable are often used interchangeably, technically a wire is one electrical conductor and a cable is multiple conductors, or a group of wires, encased in sheathing.
Electric wires are typically made of aluminum or copper. They are either bare or insulated and typically covered in a thin layer of thermoplastic. If they have a thermoplastic sheath, then the thermoplastic is colored to indicate whether the wire is a neutral, ground or hot wire in your electrical installation. We discuss wire colors in a section of this guide.
Cables contain at least a neutral wire, ground wire and hot wire that are twisted or bonded together. Depending on its purpose, the cable may contain more wires. The wires in a cable are insulated in their own color-coded layer of thermoplastic. The group of wires is then encased in an outer sheath to make up the single cable.
The most common types of electrical wires used in residential applications are usually nylon coated thermoplastic with a high-heat resistance. Wires are labeled with the THHN/THWN, material, maximum voltage rating and gauge.
Here’s what the letters stand for:
T – Thermoplastic insulation
H – Heat resistant
HH – High heat resistance up to 194 degrees Fahrenheit
W – Rated for wet locations
N – Nylon-coated to resist damage from oil or gasoline
X – Synthetic polymer, flame-resistant
THHN is made for temperatures up to 75 degrees Celsius. THWN can usually handle higher temperatures in both dry and wet conditions.
Most wire will be marked “CU” for copper, the most common conductor of residential electricity. Because electricity travels on the outside of copper wire, these wires are insulated to protect against fire and shock.
Aluminum wire is more conductive than copper wire, but it also degrades faster. For this reason, aluminum wire typically isn’t used in homes. Older wire could be aluminum or copper-clad aluminum. To comply with NEC guidelines, aluminum wire should only be installed by a professional electrician.
The maximum voltage rating will be a number such as 600, which indicates the maximum voltage the wire can carry. The average household voltage is 120 to 240 volts.
To calculate the maximum wattage a wire or cable can hold, multiply amperage by voltage. Amps x Voltage = Watts.
A wire’s color tells you the purpose of the wire. The NEC references the white conductor as the grounded conductor, the green or bare as the equipment grounding conductor, and the other colors as the ungrounded conductors. Typically, white wire is neutral wire and green or bare wire is ground wire. Any other color is usually a hot wire that carries an electrical current.
Safety Tip: Always test wires with a volt checker. A neutral can be just as dangerous as a hot wire. It still has the potential to electrocute you. It can also "ground out" and electrify any metal it meets. Treat every wire as though it’s a hot wire. If you have any uncertainty as to whether a white wire is used as neutral or hot in a project, check with a professional electrician.
The wire gauge indicates the electrical wire sizing, as defined by the American Wire (AWG) system. The most common gauges are 10, 12 or 14. The gauge and diameter of the wire are inversely related. In other words, as the gauge number gets higher, the diameter of the wire gets smaller. For example, a 10-gauge wire is bigger than a 12-gauge wire. Larger wires can carry more amperage and wattage than smaller wires.
Tip: If a project calls for longer lengths of wire (such as 80 or more feet from the breaker), increase the gauge size to ensure that enough electricity can pass through it.
The below electrical wire sizing shows both the recommended and the most common wire gauges. Here are the recommended uses for each gauge.
Wire and Cable Gauge: 14-gauge
Wire and Cable Gauge: 12-gauge
Wire and Cable Gauge: 10-gauge
Wire and Cable Gauge: 8-gauge
Wire and Cable Gauge: 6-gauge
All the information you need to know about a type of cable is printed on its sheathing. Use the following to determine if a cable is right for a project:
There are several different types of electrical cables. Each have their own specific purposes and applications. Below are common types of electrical cables used in homes and businesses:
NM-B Cable
UF Cable
AC
Metal-Clad Cable
Coaxial Cable
HDMI Cable
Speaker Cable
Category 5e Cable
Lamp Wire
Landscape Cable
Sprinkler System Cable
Tip: Both NM and AC cable require special cutting tools that cut the sheathing but not the internal wires. They also require bushings inserted in the ends to prevent the sharp edges of the metal from damaging the wires. Special electrical boxes and connectors are also required.
Knowing how to tell the difference between types of electrical wires and cables ensures that your home's power supply operates at peak efficiency and safety. Check with your local building inspector before starting any electrical wiring and cable project. Be sure to obtain required permits and have them inspected for compliance with local codes once complete. Need help identifying a tool or material? Find products fast with image search in The Home Depot Mobile App. Snap a picture of an item you like and we'll show you similar products.