Table of Contents
The non-metallic (NM) designation refers to the outer sheathing that bundles individual wires together like a cable. This is in contrast to metallic sheathed cable or conduit wiring, in which the bundle of individual conductors is protected by some form of a metal coil or metal conduit.
What is the difference between NM and NM-b wire?
Type NM is identified by the size of the conductors and number of them. For example, the very commonly used Type NM 12-2 cable contains two 12 American Wire Gauge (AWG) insulated conductors. When the letter B is appended, as in NM-B cable, it indicates that the conductor insulation is rated for 90 degrees C.
What does NMB mean for wire?
NMB stands for non-metallic because it has a PVC jacket instead of a metal-clad jacket. It is a basic indoor electrical wire used to deliver power from an electrical box to lights, outlets and appliances.
What does CU nm-B W G wire mean?
New NM cable contains two or more insulated conducting wires and usually a bare ground wire. A ground wire is indicated by “G,” “w/G,” or “with Ground.” The wire material is indicated by “CU” for copper and “AL” for aluminum.
What is an NM cable?
Sometimes known as “Romex,” named for one of the common brand names, NM cable is a flexible electrical cable that features an outer plastic sheathing that protects two or more insulated conductors, as well as a bare copper ground wire. Aug 12, 2021.
Can you use nm-b outside?
Under the 2008 code, you must use UF cable anytime NM-style cable (even in conduit) exits the side of the house. That is, you are no longer allowed to put NM-B cable in watertight conduit outside of the house in wet locations.
Is NMB the same as Romex?
Other NM Wire Brands. Romex brand NM-sheathed is not the only brand of NM wire but it is the predominant brand in North American sales.
What is the difference between Thhn and NM-B?
Whereas THHN is a cable with a single thermoplastic high heat-resistant nylon wire, NM-B wire is a sheathed cable with multiple conductors. The conductors inside the NM-B wire are either insulated or uninsulated, and the former is actually THHN, which commonly leads to confusion between the two types of cables.
What is the difference between NM and UF wire?
The primary difference between standard NM and underground feeder (UF) cable is in the cable construction. Standard NM cable contains wires that are wrapped with paper and a relatively loose plastic sheath. UF cable has wires that are completely encased in solid plastic.
Can NM cable be run in conduit?
While the National Electrical Code does not expressly forbid inserting NM cable inside conduit, it is, in practice, very difficult to do so and very few professional electricians will do such an installation.
Can I use UF-B instead of NM-B?
UF electrical wire is perfectly suitable for most NM-B applications, though it is unnecessary to use it because it is too expensive for indoor applications. When used as NM, UF-B has to comply with the standards found in NEC 2008 and NEC 2011 Article 334.
Why is UF-b cheaper than NM?
Currently, many big box stores have the UF-B marked less than the NM-B cable. That’s because the price is not as inflated from demand like NM-B. NM-B is also used more frequently because it is WAY easier to work with.
What is UF wire?
UF Cable. ”UF” stands for underground feeder; rated for in-ground and damp-area installation. Looks like NM-B cable but the wires are embedded as a group in solid thermoplastic (rather than individually encased in flexible thermoplastic).
What is 2 wire NM cable?
A 2-wire NM contains one black wire (usually line) and one white wire (usually neutral) and a bare ground wire. When used in switch wiring, the white wire is sometimes used as a line wire.
Can NM cable be exposed?
Section 336-6 permits NM cable to be installed in exposed locations and has permitted this installation technique since the introduction of NM cable into the Code in the 1930s. If installed exposed, the cable must closely follow the building surface or be installed on running boards.
What NM cable is used in wet locations?
Type AC cable is approved by the NEC for use only in dry locations. In order to comply with the NEC for use in wet locations, interlocked Type MC Cable must have a corrosion resistant jacket and wet location rated conductors. A common style cable that is rated for wet locations is a standard MC Cable with a PVC jacket.
Can I use nm wire in conduit outside?
7 Answers. Yes, NM cable can be in conduit. In fact. NEC calls for it to be in conduit, when protection from physical damage is required.
Can I run Romex in PVC outside?
Yes, they can be used outdoors, it is better to be safe than sorry. We recommend using a conduit when running the wire underground. Not only is it code, but also a good practice to ensure long life of the wire.
Is it OK to use Romex outside?
Romex is a type of electrical wire used in various applications. Romex wires cannot be used outdoors because, if it gets wet with water, gas, oil or another solvent, these liquids could penetrate the jacket and ruin the connection by getting in contact with the bare copper ground wire.
What type of electrical wire is used for outdoors?
(Type UF cable is the most commonly used nonmetallic cable for residential outdoor wiring runs.) UF cable can be direct buried (without conduit) with a minimum of 24 inches of cover.
When did nm-b wire come out?
Also in 1984, NM-B cable was developed and required to have 90°C rated individual conductors, and a 75°C outer jacket (see Fig.
