Article 334 Nonmetallic-Sheathed Cable Types NM, NMC, and NMS

I. General

334.1

Scope

334.2

Definition

Nonmetallic-sheathed cable is a cable in which the insulated conductors are enclosed in a nonmetallic material that is moisture-resistant and flame-retardant. The cable is put together at the factory. There are definitions for NM, NMC, and NMS.

334.6

Listed

 

II. Installation

334.10

Uses Permitted

These types of cable can be used in one- and two-family dwellings, multifamily dwellings of types III, IV, and V construction except as noted in Section 334.12, and cable trays when they are noted for this use. These cables can also be used in other structures of Types III, IV, and V construction with limitations. Type NM cable can be used both in dry locations exposed and concealed as well as being fished in air voids of block and tile if it is not damp or moist. Type NMC cable can be used exposed or concealed in damp, dry, or corrosive locations, inside and outside of block walls, and in shallow chases protected against nails or screws. Type NMS can be used in the same locations as Type NM. The reader is referred to this section of the NEC® for a complete list of locations where these cables can be used.

334.12

Uses Not Permitted

Type NM, NMC, and NMS cannot be used in any dwelling not permitted in 334.10(1), (2), and (3); as service entrance cable; exposed in suspended or dropped ceilings in other than one family, two family, and multifamily dwellings; in commercial garages; in motion picture studios; in theatres and the like unless otherwise provided in the NEC®; in hoistways or on elevators or escalators; in storage battery rooms; in hazardous locations unless otherwise provided in the NEC®; and embedded in poured cement, concrete, or aggregate. There are additional limitations for Types NM and NMS cable. The reader is referred to this section of the NEC® for a complete list of locations where types NM, NMC, and NMS are not permitted.

334.15

Exposed Work

334.17

Through or Parallel to Framing Members

334.23

In Accessible Attics

334.24

Bending Radius

334.30

Securing and Supporting

The cable must be secured at least every 1.4 m (4½ ft.) and not more than 300 mm (12 in.) from a fitting, box, or cabinet. There are requirements for cable trays, unsupported cable, and wiring devices without a separate outlet box.

334.40

Boxes and Fittings

334.80

Ampacity

 

III. Construction Specifications

334.100

Construction

334.104

Conductors

334.108

Equipment Grounding

334.112

Insulation

334.116

Sheath






Pocket Guide to the National Electrical Code 2005
Pocket Guide to the National Electrical Code(R), 2005 Edition (8th Edition)
ISBN: 0131480014
EAN: 2147483647
Year: 2004
Pages: 120
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