Electrical Wiring, a fundamental aspect of building infrastructure, often uses insulated cables; romex is another name for these non-metallic sheathed cables (NM cables). The National Electrical Code (NEC), a widely adopted standard in the United States, governs the safe installation of these residential electrical systems. Southwire Company, a leading manufacturer, produces a substantial amount of NM cables, and their brand name Romex, has become synonymous with this type of wiring.
Image taken from the YouTube channel Mancycle DIY , from the video titled Types of Romex Explained – 14/2 14/3 12/2 and 12/3 – WIRING BASICS .
Romex Revealed! What Else Can You Call This Electrical Wire?
Understanding electrical wiring is crucial for both DIY enthusiasts and professionals. "Romex" is a widely used term, but it’s essentially a shorthand for a specific type of electrical cable. Let’s explore the other names and technical aspects associated with it, focusing on the key concept that romex is another name for certain types of non-metallic sheathed cables.
Understanding NM-B Cable
The most technically accurate way to describe "Romex" is by its broader classification: Non-Metallic Sheathed Cable, specifically type NM-B. When someone says "Romex," they are almost always referring to NM-B cable.
What does "NM-B" mean?
NM-B is an acronym that breaks down the cable’s construction and intended use:
- N: Non-Metallic sheathing. This indicates that the conductors are encased in a non-metallic outer jacket.
- M: Indicates it may be used for both concealed or exposed work in normally dry locations. (Older NM cable could only be used in concealed work).
- B: The "B" signifies an updated version of the cable, typically indicating improved heat resistance (e.g., a higher temperature rating than older NM cable).
Key Features of NM-B Cable
- Insulation: Individual conductors within the cable are insulated with thermoplastic materials.
- Ground Wire: It includes a bare or insulated grounding conductor for safety.
- Sheathing: The outer jacket provides protection against physical damage and environmental factors within the specified environment.
- Voltage Rating: Typically rated for 600 volts.
- Common Sizes: Available in various gauges (e.g., 14, 12, 10, 8, 6 AWG) to accommodate different amperage requirements.
Other Descriptive Terms
While NM-B is the most accurate alternative name for "Romex," several other descriptive phrases are commonly used. These aren’t technically precise but help in understanding the cable’s function and application.
Non-Metallic Cable
This is a more general term that encompasses NM-B cable and other types of non-metallic sheathed cables. However, when someone says "non-metallic cable," they’re very likely referring to NM-B.
Building Wire
This is a very broad term, and NM-B cable falls under this umbrella. "Building wire" includes various types of cables and single conductors used for wiring buildings. It’s not a direct substitute, as many types of building wire are not NM-B.
Residential Wiring Cable
This description is fairly accurate as NM-B cable is very commonly used in residential construction. Its ease of installation and cost-effectiveness make it a popular choice for wiring homes.
Common NM-B Cable Configurations
NM-B cable is typically described by the number of conductors it contains and the gauge of those conductors. Examples are listed below:
- 14/2 NM-B: Two conductors, 14 gauge, with a ground wire. Generally used for 15-amp circuits.
- 12/2 NM-B: Two conductors, 12 gauge, with a ground wire. Commonly used for 20-amp circuits.
- 14/3 NM-B: Three conductors, 14 gauge, with a ground wire. Used for three-way switches or other circuits requiring an extra conductor.
- 12/3 NM-B: Three conductors, 12 gauge, with a ground wire. Used for three-way switches or other circuits requiring an extra conductor, with a 20-amp capacity.
The first number indicates the AWG (American Wire Gauge) size of the current-carrying conductors. The second number represents the number of current-carrying conductors within the cable (excluding the ground wire).
Situations Where Romex/NM-B is Not Suitable
It’s vital to understand where NM-B cable cannot be used. While versatile, there are limitations.
- Wet Locations: NM-B cable is not designed for direct burial or use in wet or damp locations. Use UF (Underground Feeder) cable in these environments.
- Exposed to Physical Damage: In areas where the cable is likely to be physically damaged (e.g., workshops, garages), it needs to be protected by conduit.
- Certain High-Temperature Environments: While NM-B cable has a temperature rating (typically 90°C for the conductors, but limited to 60°C for ampacity calculation), it might not be suitable for extreme high-temperature environments. Consult local codes for specifics.
- Embedded in Concrete: NM-B cable is generally not approved for embedding in concrete. Use conduit to protect the wiring.
Romex FAQs: Decoding Electrical Wire Names
Here are some frequently asked questions about Romex and its common alternative names.
What exactly is "Romex"?
Romex is a brand name, but it’s become a common generic term for non-metallic sheathed (NM) electrical cable. Essentially, romex is another name for this type of wiring used in residential building projects. It consists of two or more insulated wires wrapped in a plastic jacket.
Besides "Romex", what are some other common names for this type of wire?
Besides Romex, you might hear this type of wire referred to as NM cable, NM-B cable (the most common modern type), or simply non-metallic sheathed cable. Again, romex is another name for the same thing.
Can I use any electrical wire, or does it have to be "Romex" for certain applications?
You don’t have to use "Romex" brand wire. As long as the wire is properly rated NM (non-metallic sheathed) cable of the correct gauge and voltage for your application, any brand is usually acceptable. Romex is another name for one specific brand of this type of wire, not a specific requirement. Always consult local codes and a qualified electrician.
Where is Romex (NM cable) typically used?
Romex, or non-metallic sheathed cable, is primarily used for interior wiring in residential buildings. This includes wiring for outlets, lights, and appliances. It is typically not suitable for direct burial or outdoor use without proper protection. Romex is another name for a common choice for home wiring.
So, next time you’re working on a project involving electrical wiring, remember that romex is another name for NM cable. Hope this cleared things up, and happy wiring…safely of course!