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What NEC covers NM cable?
Article 334 covers the use, installation, and construction specifications of nonmetallic-sheathed cable.
Where can NM cable be used?
The standard NM cable used for interior residential wiring inside walls and floor and ceiling cavities is known as NM-B. This cable is approved for use in dry locations only; you will never see it used in outdoor locations or buried beneath the ground.
How many conductors are in a typical NM cable?
NM cable comes in many wire gauges, but most household circuits will use 12-gauge or 14-gauge wire, with either two or three conductors inside (plus the bare copper ground wire).
When can NM cable be used?
Type NM cable is permitted to be installed in occupancies that are of Types III, IV, and V construction other than dwelling type. However, it must be concealed within walls, floors or ceilings that provide a thermal barrier, per NEC 334.10(3).
What is NM NMC and NMS cable?
Type NMC. Insulated conductors enclosed within an overall, corrosion resistant, nonmetallic jacket. Type NMS. Insulated power or control conductors with signaling, data, and communications conductors within an overall nonmetallic jacket.
When can NM cable not be used?
334.10 Uses Permitted for Nonmetallic Sheathed Cable.
| A: | NM cable is NOT permitted in a two-family dwelling. |
|---|---|
| B: | NM cable is NOT permitted in a structure exceeding one floor above grade. |
| C: | NM cable is permitted to be run exposed in dropped or suspended ceilings in multifamily dwellings. |
Where can NM cable not be used?
Type NM cable cannot be run outdoors even if it is run in a raceway because this is considered to be a wet location. Type NM cable cannot be run in any raceway other than using it as a sleeve in accordance with 334.15(B) and 300.15(C) or in accordance with 334.12(A)(1) Exception.
Is Romex wiring good?
Why Romex Beats The Old Stuff 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. Longer-lasting due to copper metal composition.
Where can NM not be used?
Can I use NM cable outdoors?
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 do I need to know about installing NM cable?
The first thing you must do is determine the classification for the type of construction. Type NM cable is permitted to be installed in occupancies that are of Types III, IV, and V construction other than dwelling type. However, it must be concealed within walls, floors or ceilings that provide a thermal barrier, per NEC 334.10 (3).
Is an equipment-grounding conductor required in type NM cable?
Prior to the 2005 NEC, an equipment-grounding conductor was permitted in Type NM cable, but a proposal accepted for the 2005 NEC now requires that Type NM cable must have, in addition to the insulated conductors, an insulated or bare conductor for equipment-grounding purposes only. See sections 404.9 (B) and 334.108.
Does the voltage rating of NM cable matter?
However, it must be concealed within walls, floors or ceilings that provide a thermal barrier, per NEC 334.10 (3). The voltage rating is not the problem. Type NM cable is rated for use at 600 volts or less. See section 334.10 (3).
What is the difference between SE cable and NM cable?
This change was made for the 2008 NEC since SE cable often contains similar conductor insulation as NM cable, and where installed inside walls and in insulation, SE cable has heat dissipation similar to NM cable.