Article 350 Liquidtight Flexible Metal Conduit: Type LFMC
Liquidtight Flexible Metal Conduit (LFMC). A raceway of circular cross section having an outer liquidtight, nonmetallic, sunlight-resistant jacket over an inner flexible metal core with associated couplings, connectors, and fittings for the installation of electric conductors.
- Where conditions of installation, operation, or maintenance require flexibility or protection from machine oils, liquids, vapors, or solids.
- In hazardous (classified) locations where specifically permitted by Chapter 5.
- For direct burial where listed and marked for the purpose.
- Conductors or cables rated at a temperature higher than the listed temperature rating of LFMC conduit shall be permitted to be installed in LFMC, provided the conductors or cables are not operated at a temperature higher than the listed temperature rating of the LFMC per 110.14(C).
Exception: LFMC of metric designator 12 (trade size 3/8) shall be permitted as covered in 348.20(A).
Informational Note: See 300.1(C) for the metric designators and trade sizes. These are for identification purposes only and do not relate to actual dimensions.
Cables shall be permitted to be installed where such use is not prohibited by the respective cable articles. The number of cables shall not exceed the allowable percentage fill specified in Table 1, Chapter 9.
Exception No. 1: Where LFMC is fished between access points through concealed spaces in finished buildings or structures and supporting is impractical.
Exception No. 2: Where flexibility is necessary after installation, lengths from the last point where the raceway is securely fastened shall not exceed the following:
- 900 mm (3 ft) for metric designators 16 through 35 (trade sizes (1/2 through 11/4)
- 1200 mm (4 ft) for metric designators 41 through 53 (trade sizes 11/2 through 2)
- 1500 mm (5 ft) for metric designators 63 (trade size 21/2) and larger
For the purposes of the exceptions, listed LFMC fittings shall be permitted as a means of securement and support.