NM-B ROMEX WIRE
When thinking of wiring a house, you can get spoilt for the wide range of cables and wire products in the market. Most service wires are made of copper and others of aluminum. Others are meant for indoors while others for the outdoors. However, their applications are highly specialized and you need to take uttermost care when making a selection.
Among those used for home wiring is the Romex or nm-B cable. NM-B means non-metallic because it comes with a jacket made of polyvinyl material rather than a metal clad material. So, here’s a non-metallic clad cable which will serve your wiring needs just as effectively as other the metal clads.
The outer PVC sheathing bundles together the individual conductors and protects them from physical and chemical damages. NM-B wire often transmits electric current from the electric switchboards to the appliances, lights and outlets.
Here’s what makes the Romex Wire Unique
Non-metallic sheathed cable conductors comprise of two or more insulated conductors placed in a non-metallic sheath. The coating on Romex cable is moisture resistant, non- conducting and flame retardant. They can be used in damp areas such as basements and marshes.
Romex residential wire is classified by NEC as an underground feeder; non-metallic sheathed cable.
Underground Feeders seem to be similar to Romex cables only that the UF cables have a solid plastic core. They also can’t be rolled between fingers.
NEC Regulations on Romex Conductors
- They are purposed for permanent wiring in residential buildings and should never be used as a substitute for extension cords or appliance wiring.
- They should be secured and clamped to fixtures, device boxes and junction boxes.
- They should to be secured at intervals that don’t go beyond 5.5 ft. they ought to be secured within a radius of 12 inches of panels and junction boxes they are attached to.
- Support devices that may cause damage to the cables are not allowed. These may include overdriven staples or bent nails.
NM-B (Romex) circuit sizes
Various manufacturers produce different types of nm-B cables but they must all be in accordance to the regulations set by the National Electric Code. Due to the amps they transmit, the 10, 12 and 14 AWG circuit sizes are the most common kinds of Romex cables in the market. These three sizes are the smallest electrical wire circuit sizes. The 12 AWG cable has 20 amps, 14 gauge one is rated for 15 Amps and the 10 gauge rated for 30 amps.
The circuit sizes can be differentiated by color. The 12 AWG nm-B cables come with a white outer jacket while the 12 AWG comes with a yellow jacket while the 10 AWG has a white outer jacket.
There are larger sizes of nm-B cable. These are those that range from 8 AWG through 2 AWG and have two or three conductors. The lower the gauge size, the larger the cable is. The bare copper ground wire is an extra wire, important but not considered when indicating the cable as NM-B 6/3.
For instance, 6/3 is to say that it has three insulated conductors which are color-coded and an extra ground wire that has no insulation.
The 6/3 nm-B cables are used to hook up indoor shop equipment, an indoor hot tub or large appliances.
Due to their inflexibility, they cannot be used for outdoor purposes.
14 denote the size of the cable while 2 represents the number of conductors in the cable. This cable is used as branch circuits for outlets, switches and other loads in home wiring. It may as well be used in exposed and concealed work in dry places. This is not a direct burial cable. Its flexible sheath makes it easier to run it through conduits in studs.
It has a black hot, red hot, white neutral, and bare copper. This solid bare copper stranded cable weighs 57 pounds per 100 feet. It has 15 amps and supplies up to 600 volts of power. The white 14/2 cable works best below 90°C.
This is a yellow non-metallic sheathed cable. It comes with a copper conductor that has a 12 AWG gauge size. It has 2 conductors with 20 amps transmitting power at 600 volts. It also has a PVC jacket and nylon jacketing protecting the cable from damages. It is constructed as per the NEC regulations and listed under the UL standard 83,719. The 12/2 Romex has a black hot, a white neutral and an unsheathed copper wire for ground.
The two above are the most common types of nm-B cables. The following are other widely used nm-B cables. The first number indicates the gauge size of the cable while the second one indicates the number of conductors.
- 8/3 Romex cable
- 14/3 Romex cable
- 10/2 Romex wire
- 12/4 Romex wire
- 8/2 Romex wire
- 8/4 Romex wire
- 6/2 Romex wire
- 10/3 Romex wire
- 12/3 Romex wire
NM-B wire approvals and Certifications
In every situation that calls for the use of electric cables it is vital to verify the safety features of the cable you desire to use. NM-B cables are tested and approved by several international standards organizations. They have been approved by;
- RoHS
- UL719
- UL83
- REACH
- ASTM B3 and B8
- AA59544
NM-B Wire Applications
NM-B wires are only used for indoor applications. The vinyl jacket could get ruined if used outdoors and the bare copper wire could be compromised. Outdoor application cables must either be Underground Feeders (UFB), metal clad (MC) or individual THHN. Romex cables are used for home electrical wiring applications. These may include;
- Stove
- Hot tub
- Dish washers
- New electrical panels (indoors)
- Refrigerators
Appliances with 8 AWG and 6 AWG such as stoves and dryers require more power to operate because they have bigger gauge sizes.
Did you find this post insightful? We have more similar articles on other service entrance cables on our blog. We would like to know your feedback and comments shared here concerning the nm-B cables. Feel free to get in touch with our support team on our live chat on our website today.