Romex wire has been in use for decades. It’s a widely used cable and is one of the most commonly used wires in home construction and businesses. However, there are some things most people don’t know about Romex: what types are there, what temperatures they are rated for, and more information on how they work. Let’s get started on learning everything you need to know about Romex wires.

What is Romex wire?

Romex wire is a non-metallic electrical wire used for power, lighting, and communications circuits. A Romex conductor is a plastic or non-metallic conductor that is used in electrical wiring. The term Romex refers to the Rome Cable Corp, which developed and produced the plastic insulation in the early 1900s.

Romex is now found in most homes and commercial buildings because it has many advantages over other types of wire. It has been upgraded several times since its introduction and continues to improve today with newer types of insulation materials, improved designs, and more flexible connectors. The most common type of Romex is covered with a black plastic jacket called an insulator which protects the conductors from moisture and keeps them together when they are twisted together into strands.

What is a non-metallic wire?

A non-metallic wire is a type of insulated wire that doesn’t have any metal in its makeup. It’s usually made from plastic and rubber, but it can also be made with other materials. The insulation in non-metallic wires is generally very good at protecting against ground faults, which means it’s a better choice than bare copper or aluminum.

The main benefit of non-metallic wires is that they are much cheaper than other types of insulation. They also don’t cause corrosion problems like bare copper or aluminum wire do. The downside of non-metallic wires is that they don’t offer as much resistance to moisture as are found in other types of insulation, such as polyvinyl chloride (PVC). This means they may not be ideal for applications with heavy rain or condensation inside your home’s electrical systems.

What is Romex wire used for?

Romex is a standard of wire used worldwide, and you can find it everywhere. The most common uses of Romex are:

  • Romex wire is used for electrical wiring in homes and buildings. It connects electrical appliances such as washing machines, dryers, dishwashers, refrigerators, stoves, televisions, radios, and more.
  • Romex wire is also used for telephone lines. Telephone lines would be connected from one building to another using Romex wire. It’s also used to connect two buildings with each other because they are in different locations.
  • Romex wires are also used for outdoor use, like around your home or business. You could use it for outdoor lighting or outdoor air conditioning units that keep your home cool during hot days in the summertime.

Types of Romex wire?

Romex wire comes in a variety of sizes, thicknesses, colors, and gauges, depending on the application. Some common types of Romex wire are:

  1. 6/3 Romex: A 6/3 Romex wire comes with a Rated Amperage of 50A and is commonly used in Range, Heatpump, and On-demand electric water heaters.
  2. 8/2 Romex: An 8/2 Romex wire only has to carry 40 amps. It is commonly used for smaller light fixtures and outlets.
  3. 8/3 Romex: An 8/3 Romex wire comes with an allowable ampacity of 40 Amps. It is commonly used in residential building wiring as a branch circuit for switches and outlets.
  4. 14/2 Romex: A 14/2 Romex wire comes with a Rated Amperage of 15A and is commonly used in lighting circuits.
  5. 12/2 Romex: A 12/2 Romex wire comes with a Rated Amperage of 20A and is commonly used in lighting and outlet circuits along with refrigerators.
  6. 10/2 Romex: A 10/2 Romex wire comes with a Rated Amperage of 30A and is commonly used in an electric water heater and baseboard heaters.
  7. 10/3 Romex: A 10/3 Romex wire comes with a Rated Amperage of 30A and is commonly used with an electric clothes dryer.

Romex wire chart

Conductor Insulation
Thickness
(mils)
Ground Wire Allowable
Ampacity
+
Size (AWG or kcmil) No. of conductors No of strands No. Size
(AWG)
No. of strands
TWO CONDUCTOR
14 2 1 19 14 1 15
12 2 1 19 12 1 20
10 2 1 24 10 1 30
8 2 7 35 10 1 40
6 2 7 35 10 1 55
THREE CONDUCTOR
14 3 1 19 14 1 15
12 3 1 19 12 1 20
10 3 1 24 10 1 30
8 3 7 35 10 1 40
6 3 7 35 10 1 55
4 3 7 46 8 1 70
2 3 7 46 8 1 95
FOUR CONDUCTOR
14 4 1 19 14 1 15
14 4 1 19 14 1 15
12 4 1 19 12 1 20
12 4 1 19 12 1 20
10 4 1 24 10 1 30

 

FAQ

1. How much Romex wire is needed to wire a house?

The amount of Romex wire needed to wire a house depends on many factors, including the home’s size, location, and the number of circuits required. A typical single-family house has about 10 circuits per panel, translating into approximately 150 feet worth of Romex. Multifamily buildings typically require between 25 and 50 panels per circuit, which means between 250-500 feet worth of Romex would be needed for each building (depending on location). Large commercial properties often require more than 100 panels per circuit, translating into 500+ feet worth of Romex (again, depending on location).

2. Why is Romex wire so expensive?

Romex wire is expensive because it’s been around for a long time, and it has a reputation for being durable. In addition, the reason why Romex wire is so expensive has to do with its thickness and gauge. The thicker the gauge, the more electricity can be sent through it. This means that there are fewer wires in a given length of wire than there would be if it were made thinner, which in turn means that it costs more to make.

Another factor in Romex pricing is how much power each circuit requires. The more energy that needs to go through the wire, the higher the cost for that particular cable length.’

3. What does Romex wire look like?

Romex wire comes in four primary colors: white, red, blue, and green. The white Romex is the most commonly used, but it’s important to note that not all Romex wires are made equal. While all four colors represent the same type and size of wire, each color has a different core material that determines its quality.

White is made from aluminum and copper and is considered the highest quality insulation wire available. Red and blue Romex wires have copper cores and aluminum surrounds, which make them more resistant to heat than white Romex, but they’re still susceptible to moisture damage over time. Use them where you’ll be exposed to sun or rain only occasionally.
Green Romex is composed of copper, zinc, and tin, which means it’s less prone to corrosion than its counterparts.

4. How many Romex wires can be bundled together?

You can bundle up to four Romex wires together, but it’s best to stay on the safe side and not bundle more than that. The wire gauge doesn’t matter as much as how good your crimper is.

You also must be careful about how many strands there are per Romex wire. For example, if you want to use two Romex wires in one bundle and they’re both stranded wires (with no solid core), then you’ll want to ensure each strand has at least two wires in it. If only one of the two strands has a solid core, then you will have too many strands for your application.

5. What temperature is Romex wire rated for?

Romex wire is rated for temperatures up to 194°F (90°C). The higher the temperature, the weaker the wire becomes. So, if you’re wiring in a new home or updating older wiring with a new Romex cable, make sure you have an experienced electrician on-site who can determine the proper rating of the wire for your project.