336-1. Scope. This article covers the use, installation, and construction specifications of nonmetallic-sheathed cable.

(FPN): See Section 310-10 for temperature limitation of conductors.

(a) Type NM. Type NM cable shall be permitted for both exposed and concealed work in normally dry locations It shall be permissible to install or fish Type NM cable in air voids in masonry block or tile walls where such walls are not exposed or subject to excessive moisture or dampness.

(b) Type NMC. Type NMC cable shall be permitted:

1. For both exposed and concealed work in dry, moist, damp, or corrosive locations.
   
2. In outside and inside walls of masonry block or tile.
   
3. In a shallow chase in masonry, concrete, or adobe protected against nails or screws by a steel plate at least 1/16-in. (1.59-mm) thick, and covered with plaster, adobe, or similar finish.

(c) Type NMS. Type NMS cable shall be permitted for both exposed and concealed work in normally dry
locations. It shall be permissible to install or fish Type NMS cable in air voids in masonry block or tile walls where such walls are not exposed or subject to excessive moisture or dampness. Type NMS cable shall be used as permitted in Article 780.

(a) Types NM, NMC, and NMS. Types NM, NMC, and NMS cables shall not be used:

1. In any dwelling or structure exceeding three floors above grade. For the purpose of this article, the first floor of a building shall be that floor that has 50 percent or more of the exterior wall surface area level with or above finished grade. One additional level that is the first level and not designed for human habitation and used only for vehicle parking, storage, or similar use shall be permitted.
   
   Exception: An additional level shall be permitted where the renovation of attic, vehicle parking, or storage space creates a habitable floor level in an existing one-family dwelling.
   
2. As service-entrance cable.
   
3. In commercial garages having hazardous (classified) locations as provided in Section 511-3.
   
4. In theaters and similar locations, except as provided in Article 518, Places of Assembly,
   
5. In motion picture studios.
   
6. In storage battery rooms.
   
7. In hoistways.
   
8. Embedded in poured cement, concrete, or aggregate.
   
9. In any hazardous (classified) location, except as permitted by Sections 501-4(b), Exception, 502-4(b), Exception, and 504-20.

(b) Types NM and NMS. Types NM and NMS cable shall not be installed:

1. Where exposed to corrosive fumes or vapors.
   
2. Where embedded in masonry, concrete, adobe, fill, or plaster.
   
3. In a shallow chase in masonry, concrete, or adobe and covered with plaster, adobe, or similar finish.

(a) To Follow Surface. The cable shall closely follow the surface of the building finish or of running boards.

(b) Protection from Physical Damage. The cable shall be protected from physical damage where necessary by conduit, electrical metallic tubing, Schedule 80 PVC rigid nonmetallic conduit, pipe, guard strips, or other means. Where passing through a floor, the cable shall be enclosed in rigid metal conduit, intermediate metal conduit, electrical metallic tubing, Schedule 80 PVC rigid nonmetallic conduit, or other metal pipe extending at least 6 in. (152 mm) above the floor.

(c) In Unfinished Basements. Where the cable is run at angles with joists in unfinished basements, it shall be permissible to secure cables not smaller than two No. 6 or three No. 8 conductors directly to the lower edges of the joists. Smaller cables shall either be run through bored holes in joists or on running boards.

(d) In Accessible Attics. The installation of cable in accessible attics or roof spaces shall also comply with Section 333-12.

(FPN): See Section 370-17(c) for support where nonmetallic boxes are used.

Exception No. 1: For concealed work in finished buildings or finished panels for prefabricated buildings where such supporting is impracticable, it shall be permissible to fish cable between access points.

Exception No. 2: A wiring device identified for the use, without a separate outlet box, incorporating an integral cable clamp shall be permitted where the cable is secured in place at intervals not exceeding 4 1/2 ft (1.37 m) and within 12 in. (305 mm) from the wiring device wall opening, and there shall be at least a 12-in. (305-mm) loop of unbroken cable or 6 in. (152 mm) of a cable end available on the interior side of the finished wall to permit replacement.

(a) Construction. The outer cable sheath shall be a nonmetallic
material.

1. Type NM. The overall covering shall be flame retardant and moisture resistant.
   
2. Type NMC. The overall covering shall be flame retardant, moisture resistant, fungus resistant, and corrosion resistant.
   
3. Type NMS. Type NMS cable is a factory assembly of insulated power, communications, and signaling conductors enclosed within a common sheath of moisture-resistant, flame-retardant, nonmetallic material. The sheath shall be applied so as to separate the power conductors from the communications and signaling conductors. The signal conductors shall be permitted to be shielded. An optional outer jacket shall be permitted.

(FPN): For composite optical cable, see Sections 770-4 and 770-52.

(b) Conductors. The insulated power conductors shall be one of the types listed in Table 310-13 that is suitable for branch-circuit wiring or one that is identified for use in these cables. The power conductors shall be sizes No. 14 through No. 2 with copper conductors or sizes No. 12 through No. 2 with aluminum or copper-clad aluminum conductors. The signaling conductors shall comply with Section 780-5. In addition to the insulated conductors, the cable shall be permitted to have an insulated or bare conductor for equipment grounding purposes only. Where provided, the grounding conductor shall be sized in accordance with Article 250. Conductors shall be rated at 90°C (194°F). The ampacity of Types NM, NMC, and NMS cable shall be that of 60°C (140°F) conductors and shall comply with Section 310-15.

(FPN): Types NM, NMC, and NMS cable identified by the markings NM-B, NMC-B, and NMS-B meet this requirement.

Exception: The 90°C (194°F) rating shall be permitted to be used for ampacity derating purposes provided the final derated ampacity does not exceed that for a 60°C (140°F) rated conductor.