E3908.8.1 Flexible Metal Conduit
Flexible metal conduit shall be permitted as an equipment grounding conductor where all of the following conditions are met:
- The conduit is terminated in listed fittings.
- The circuit conductors contained in the conduit are protected by overcurrent devices rated at 20 amperes or less.
- The size of the conduit does not exceed trade size 11/4.
- The combined length of flexible metal conduit and flexible metallic tubing and liquid-tight flexible metal conduit in the same ground return path does not exceed 6 feet (1829 mm).
If 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, an equipment grounding conductor shall be installed. [250.118(5)]