Your home is wired with different types of wire. Each has its specific use to accommodate the load and conditions it is exposed to. Let’s examine what each type is and how it is used in the home’s electrical system.
Electrical wire can be the stranded type or a solid form. Every wire except the ground wire is coated with a non-conductive coating of insulated material. Electrical wiring is rated in gauge for it’s size and amp rating.
Electrical wire can come in rolls or on spools. Lengths of wire vary from standard cuts of 50, 100, 250, 500 and 1,000 feet, but can be special ordered for specific lengths. The homeowner will generally choose the shorter lengths, while the contractors chooser much larger rolls, knowing that they will use it somewhere down the road. The homeowners electrical jobs may be limited, unlike the contractor.
There are low voltage wires used in homes like phone, cable, doorbell, thermostat, and security camera cables. These will not carry standard home voltages of 120 volts or 240 volts, like most everything runs on in your home.
The larger voltages, 120 and 240 volt, run circuitry and appliances in your home. The service entrance to your home may come in either overhead or underground. The underground wiring provides for a more pleasant view, but the dangers of underground wiring and digging have to be considered. Overhead wiring is not without its own dangers, especially with children with kites and farmers with booms or grain augers extended.
Electrical wiring colors and labeling often tell the tale of the wire you are installing You can tell a lot about a piece of electrical wire from the label on it. It will tell the type, size, and intended uses. It also tells whether it is weather resistant, sunlight proof, or heat rated. The wire colors tell of the specific use of the wire. It may be a “hot” wire, a neutral wire, or even a ground wire. For those of use that know, wire colors tell us how to use each wire, where to connect it, and most importantly where not to use it.
If you are like many of the beginner electrical project DIYers, you may walk into the electrical department and see all types of electrical wire. There is wiring for low voltage projects, wiring for circuits to run appliances, lighting and more, and then wiring for electrical services. But as I watch some of you look over this wiring in the stores, I often here things like, “This wire looks big enough” and “What;s the difference? This smaller wire is much cheaper and will work just fine!” It’s a very scary set of comments to someone who knows the difference and knows what can happen if the wiring cannot handle the electrical load. Let’s take a look at the types of wire that you will likely need in your home.
1. Triplex Wire
Triplex is an aerial cable that the utility company uses to feed the power pole. This wire ties to the wires sticking out of the weather head.
2. Main Feeder Wires
These wires are usually type THHN wire and are rated for 125% of the load required. These are usually black insulated wires coming out of the service weather head.
3. Panel Feed Wires
These wires are also type THHN, like the main feeders. A typical 100-amp service would have a #2 THHN set of wires. They would then be rated at 125 amps. This would protect the wires if the amperage was a full 100 amps.
4. Non-Metallic Sheathed Wire (NM)
This wire, commonly called Romex, is a plastic coated wire that has either two or three conductors and a bare ground wire. This is the typical wiring used in most homes. The rating for this wire is either 15 amps, 20 amps, or 30 amps, depending on the installation.
Photo of Single Strand Wire – Tim Thiele
Photo of Single Strand Wire. Tim Thiele
5. Single Strand Wire
When your home is piped, you’ll have to have another type of wire. Single strand wire is insulated and many of these can be pulled into the same pipe. Normally, you’ll be using THHN wire for this installation.