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NM-B is a non-metallic electrical wire used in residential building wiring for various devices and outlets. It is suitable for direct burial without an electrical conduit because of the durable rubber sheathing that protects it from damage during installation and maintenance.
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 type NM-B wire mean?
Type NM-B (Non-Metallic Sheathed Cable) is commonly used for residential wiring of luminaries, devices and appliances. Type NM-B ampacity limitation shall be in accordance with the 60ºC conductor temperature rating, as specified in the NEC.
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.
Can nm-B wire be put in conduit?
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.
What is NMB wire used for?
NM-B cable is primarily used in residential wiring as branch circuits for outlets, switches, and other loads. NM-B cable may be run in air voids of masonry block or tile walls where such walls are not wet or damp locations. Voltage rating for NM-B cable is 600 volts.
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.
What does UF B stand for on wiring?
Type UF-B (Underground Feeder and Branch-Circuit Cable) is generally used in underground, direct burial installations as branch circuits and/or feeders to outside floodlights, sewer pumps and motors, electric gates and other loads typically supplied from a distribution system.
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.
Can type NM-B Romex be exposed to corrosive vapors?
Section 334.12(B) does not allow type NM cable to be installed in wet locations or where exposed to corrosives such as chlorine but without the revised code language, sections 334.10 and 334.12(B) were in conflict with one another.
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.
Can nm B be exposed?
It could be installed exposed in a residential garage or in an attic or basement. In most cases, the NM cable must closely follow the building surface or another means of support for the cable must be provided.
Can UF-B cable be exposed?
The use of UF cable on the exterior surface of buildings or structures is permitted by Sec. If the cable is exposed to physical damage it must be protected in accordance with Sec.
Is Romex Thhn wire?
Romex® cables typically consist of multiple THHN wires bundled together and sheathed in polyvinyl chloride (PVC), making them suitable for indoor applications such as garages, interior walls and surface wiring above ground.
Does Romex need conduit?
Code and common sense both dictate that Romex shouldn’t be left exposed but must run through conduits. If you are running it through the basement or attic (or both), the wire must past through studs or be secured on top of joists or trusses.
Does Romex contain Thhn wire?
Romex wire is made out of two or three THHN wires combined with a grounding bare copper wire. Like the THHN wires, Romex wire can’t be used outside because of its minimal PVC jacket protection.
Can I run NMB in conduit outside?
When using any non metallic wire outdoor, including Romex, it is a good idea to run it through a conduit. Yes, they can be used outdoors, it is better to be safe than sorry. We recommend using a conduit when running the wire underground.
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.
Is Romex wiring safe?
Knob and Tube wiring and aluminum wiring are old and unsafe, period. Romex wire is one of the better and safer alternatives for the following reasons: Presence of a ground wire. Sheathing is flame-resistant and heat resistant, able to withstand a temperature of 90 degrees Fahrenheit.
