A. General

•333-1. Definition. Type AC cable is a fabricated assembly of insulated conductors in a flexible metallic enclosure. See Section 333-19.

•333-2. Other Articles. Type AC cable shall comply with this article and also with the applicable provisions of other articles in this Code, especially Article 300.

•333-3. Uses Permitted. Except where otherwise specified in this Code and where not subject to physical damage, Type AC cable shall be permitted for branch circuits and feeders in both exposed and concealed work and in cable trays where identified for such use.

Type AC cable shall be permitted in dry locations and embedded in plaster finish on brick or other masonry, except in damp or wet locations. It shall be permissible to run or fish this cable in the air voids of masonry block or tile walls where such walls are not exposed or subject to excessive moisture or dampness or are below grade line.

•333-4. Uses Not Permitted. Type AC cable shall not be used where prohibited elsewhere in this Code, including (1) in theaters and similar locations, except as provided in Article 518, Places of Assembly; (2) in motion picture studios; (3) in any hazardous (classified) location except as permitted by Sections 501-4(b), Exception, 502-4(b), Exception, and 504-20; (4) where exposed to corrosive fumes or vapors; (5) on cranes or hoists, except as provided in Section 610-11, Exception No. 3; (6) in storage battery rooms; (7) in hoist-ways or on elevators, except as provided in Section 620-21; or (8) in commercial garages where prohibited in Article 511.

B. Installation

•333-7. Support. Type AC cable shall be secured by approved staples, straps, hangers, or similar fittings so designed and installed as not to damage the cable at intervals not exceeding 4 1/2 ft (1.37 m) and within 12 in. (305 mm) of every outlet box, junction box, cabinet, or fitting.

Exception No. 1: Where cable is fished.

Exception No. 2: Lengths of not more than 2 ft (610 mm) at terminals where flexibility is necessary.

Exception No. 3: Lengths of not more than 6 ft (1.83 m) from an outlet for connections within an accessible ceiling to lighting fixtures or equipment.

Exception No. 4: Where installed in cable trays, Type AC cable shall comply with Section 318-8(b).

Exception No. 5: Armored cable installed in other than vertical runs through bored or punched holes in wood or metal framing members, or through notches in wooden framing members and protected by a steel plate at least 1/16-in. (1.59 mm) thick, shall be considered secured where the support intervals do not exceed those specified in this section and the armored cable is securely fastened in place by an approved means within 12 in. (305 mm) of each box, cabinet, conduit body, or other armored cable termination.

•333-8. Bending Radius. All bends shall be made so that the cable will not be damaged, and the radius of the curve of the inner edge of any bend shall not be less than five times the diameter of the Type AC cable.

•333-9. Boxes and Fittings. At all points where the armor of AC cable terminates, a fitting shall be provided to protect wires from abrasion, unless the design of the outlet boxes or fittings is such as to afford equivalent protection, and, in addition, an insulating bushing or its equivalent protection shall be provided between the conductors and the armor. The connector or clamp by which the Type AC cable is fastened to boxes or cabinets shall be of such design that the insulating bushing or its equivalent will be visible for inspection. Where change is made from Type AC cable to other cable or raceway wiring methods, a box, fitting, or conduit body shall be installed at junction points as required in Section 300-15.

•333-10. Through or Parallel to Framing Members. Type AC cable shall comply with Section 300-4 where installed through or parallel to studs, joists, rafters, or similar wood or metal members.

•333-11. Exposed Work. Exposed runs of cable shall closely follow the surface of the building finish or of running boards.

Exception No. 1: Lengths of not more than 24 in. (610 mm) at terminals where flexibility is necessary.

Exception No. 2: On the underside of joists where supported at each joist and so located as not to be subject to physical damage.

Exception No. 3: Lengths of not more than 6 ft (1.83 m) from an outlet for connection within an accessible ceiling to lighting fixtures or other equipment.

•333-12. In Accessible Attics. Type AC cables in accessible attics or roof spaces shall be installed as specified in (a) and (b) below.

(a) Where Run Across the Top of Floor Joists. Where run across the top of floor joists, or within 7 ft (2.13 m) of floor or floor joists across the face of rafters or studding, in attics and roof spaces that are accessible, the cable shall be protected by substantial guard strips that are at least as high as the cable. Where this space is not accessible by permanent stairs or ladders, protection shall only be required within 6 ft (1.83 m) of the nearest edge of the scuttle hole or attic entrance.

(b) Cable Installed Parallel to Framing Members. Where the cable is installed parallel to the sides of rafters, studs, or floor joists, neither guard strips nor running boards shall be required, and the installation shall also comply with Section 300-4(d).

C. Construction Specifications

•333-19. Construction. Type AC cable shall have an armor of flexible metal tape. The insulated conductors shall be in accordance with Section 333-20. Cables of the AC type shall have an internal bonding strip of copper or aluminum in intimate contact with the armor for its entire length.

•333-20. Conductors. Insulated conductors shall be of a type listed in Table 310-13 or those identified for use in this cable. In addition, the conductors shall have an overall moisture-resistant and fire retardant fibrous covering. For Type ACT, a moisture-resistant fibrous covering shall be required only on the individual conductors. The ampacity shall be determined by Section 310-15.

Exception: Armored cable installed in thermal insulation shall have conductors rated at 90°C (194°F). The ampacity of cable installed in these applications shall be that of 60°C (140°F) conductors.

•333-21. Grounding. Type AC cable shall provide an adequate path for equipment grounding as required by Section 250-51.

•333-22. Marking. The provisions of Section 310-11 shall apply, except that Type AC cable shall have ready identification of the manufacturer by distinctive external markings on the cable sheath throughout its entire length. Cables that are flame retardant and have limited-smoke characteristics shall be permitted to be identified with the suffix LS.