•349-1. Scope. The provisions of this article apply to a raceway for electric conductors that is circular in cross section, flexible, metallic, and liquidtight without a nonmetallic jacket.

•349-2. Other Articles. Installations of flexible metallic tubing shall comply with the provisions of the applicable sections of Article 300 and Section 110-21.

•349-3. Uses Permitted. Flexible metallic tubing shall be permitted to be used for branch circuits (1) in dry locations; (2) concealed; (3) in accessible locations; and (4) for system voltages of 1000 volts maximum.

•349-4. Uses Not Permitted. Flexible metallic tubing shall not be used (1) in hoistways; (2) in storage battery rooms; (3) in hazardous (classified) locations unless otherwise permitted under other articles in this Code; (4) underground for direct earth burial, or embedded in poured concrete or aggregate; (5) where subject to physical damage; and (6) in lengths over 6 ft (1.83 m).

•349-10. Size.

(a) Minimum. Flexible metallic tubing smaller than 1/2-in. electrical trade size shall not be used.

Exception No. 1: 3/8-in. trade size shall be permitted to be installed in accordance with Sections 300-22(b) and (c).

Exception No. 2: 3/8-in. trade size shall be permitted in lengths not in excess of 6 ft (1.83 m) as part of an approved assembly or for lighting fixtures. See Section 410-67(c).

(b) Maximum. The maximum size of flexible metallic tubing shall be the 3/4-in. trade size.

•349-12. Number of Conductors.

(a) 1/2-In. and 3/4-In. Flexible Metallic Tubing. The number of conductors permitted in 1/2-in. and 3/4-in. trade sizes of flexible metallic tubing shall not exceed the percentage of fill specified in Table 1,Chapter 9.

(b) 3/8-In. Flexible Metallic Tubing. The number of conductors permitted in 3/8-in. trade size flexible metallic tubing shall not exceed that permitted in Table 350-12.

•349-16. Grounding. See Section 250-91(b), Exception No. 1, for rules on the use of flexible metallic tubing as an equipment grounding conductor.

•349-17. Splices and Taps. Splices and taps shall be made in accordance with Section 300-15. See Article 370 for rules on the installation and use of boxes and conduit bodies.

•349-18. Fittings. Flexible metallic tubing shall be used only with listed terminal fittings. Fittings shall effectively close any openings in the connection.

•349-20. Bends.

(a) Infrequent Flexing Use. Where the flexible metallic tubing shall be infrequently flexed in service after installation, the radii of bends measured to the inside of the bend shall not be less than specified in Table 349-20(a).

(b) Fixed Bends. Where the flexible metallic tubing is bent for installation purposes and is not flexed or bent as required by useafter installation, the radii of bends measured to the inside of the bend shall not be less than specified in Table 349-20(b).