Article 330 Metal-Clad Cable Type MC

I. General





Metal-clad cable is Type MC. It is a cable in which the conductors are enclosed in a corrugated metal sheath or interlocking metal tape, insulated, and the entire cable is put together at the factory.

II. Installation


Uses Permitted

This cable can be used for almost all types of applications, including wet locations, provided that it will not sustain physical damage and is not prohibited in another part of the NEC®. A listing is given in the NEC® for both general uses and specific uses. In wet locations one of the following must be adhered to: moisture will not get through the metal cover, a lead sheath that will not let moisture through is put under the metal cover, or the insulated conductors enclosed by the metal cover are listed for a wet location. Refer to this section in the Code.

Type MC cable must be installed in accordance with the requirements of Articles 300, 490, 725, and Section 770.133. When installed in cable tray, direct buried, as service-entrance cable outside buildings or as aerial cable, you must refer to the appropriate articles in the NEC®.


Uses Not Permitted

This cable cannot be used in a location where it is subject to corrosive conditions that are destructive. The NEC® gives as examples direct buried cable in earth or concrete, under fills, chlorides, caustic alkalis, and the like.


Through or Parallel to Framing Members

It must comply with 300.4.


In Accessible Attics

Must comply with 320.23.


Bending Radius

The following are the allowable radii of the curve of the inner edge: for shielded conductors, use the greater of either 12 times the diameter of one conductor or 7 times the overall diameter of the cable; for interlocked armor or corrugated sheath, 7 times the diameter of the sheath; for smooth sheath, use the following:

Cable up to 19 mm (¾ in.) diameter: 10 times diameter

Cable between 19 mm (¾) and 38 mm (1½ in.) diameter: 12 times diameter

Cable larger than 38 mm (1½ in.) diameter: 15 times diameter


Securing and Supporting

There are requirements for supported and unsupported cables.


Single Conductors


Boxes and Fittings



Refer to 310.15 or 310.60 for 14 AWG and larger conductors. Use Table 402.5 for 18-16 AWG conductors. There are additional requirements for cable installed in cable tray and cable grouped together supported by messenger cable.

C. Construction Specifications



Copper, aluminum, or copper-clad aluminum must be used, either stranded or solid. The smallest sizes allowed are 18 AWG for copper and 12 AWG for aluminum or copper-clad aluminum.


Equipment Grounding





The sheath must be either smooth, welded, and corrugated or interlocking.

Article 90 Introduction


Wiring and Protection

Wiring Methods and Materials

Equipment for General Use

Special Occupancies

Special Equipment

Special Conditions


Annex C. Conduit and Tubing Fill Tables for Conductors and Fixture Wires of the Same Size

Annex D. Examples

Annex E. Types of Construction

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 © 2008-2020.
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