Article 330 Metal-Clad Cable: Type MC
Metal Clad Cable, Type MC. A factory assembly of one or more insulated circuit conductors with or without optical fiber members enclosed in an armor of interlocking metal tape, or a smooth or corrugated metallic sheath.
- For services, feeders, and branch circuits.
- For power, lighting, control, and signal circuits.
- Indoors or outdoors.
- Exposed or concealed.
- To be direct buried where identified for such use.
- In cable tray where identified for such use.
- In any raceway.
- As aerial cable on a messenger.
- In hazardous (classified) locations where specifically permitted by other articles in this Code.
- In dry locations and embedded in plaster finish on brick or other masonry except in damp or wet locations.
- In wet locations where a corrosion-resistant jacket is provided over the metallic covering and any of the following conditions are met:
- Where single-conductor cables are used, all phase conductors and, where used, the grounded conductor shall be grouped together to minimize induced voltage on the sheath.
- Where subject to physical damage
- Where exposed to any of the destructive corrosive conditions in (a) or (b), unless the metallic sheath or armor is resistant to the conditions or is protected by material resistant to the conditions:
- Ten times the external diameter of the metallic sheath for cable not more than 19 mm (3/4 in.) in external diameter
- Twelve times the external diameter of the metallic sheath for cable more than 19 mm (3/4 in.) but not more than 38 mm (11/2 in.) in external diameter
- Fifteen times the external diameter of the metallic sheath for cable more than 38 mm (11/2 in.) in external diameter
Horizontal runs of Type MC cable installed in wooden or metal framing members or similar supporting means shall be considered supported and secured where such support does not exceed 1.8-m (6-ft) intervals.
- Is fished between access points through concealed spaces in finished buildings or structures and supporting is impractical.
- Is not more than 1.8 m (6 ft) in length from the last point of cable support to the point of connection to luminaires or other electrical equipment and the cable and point of connection are within an accessible ceiling.
- Is Type MC of the interlocked armor type in lengths not exceeding 900 mm (3 ft) from the last point where it is securely fastened and is used to connect equipment where flexibility is necessary to minimize the transmission of vibration from equipment or to provide flexibility for equipment that requires movement after installation.
For the purpose of this section, Type MC cable fittings shall be permitted as a means of cable support.
For control and signal conductors minimum conductor sizes shall be 18 AWG copper, nickel, or nickel-coated copper, 14 AWG copper-clad aluminum, and 12 AWG aluminum.
Informational Note: See 300.6 for protection against corrosion.