Liquidtight Flexible Nonmetallic Conduit (LFNC)

LFNC is the all-plastic cousin of liquidtight flexible metal conduit. It flexes like Greenfield, seals against liquids, but has no metal in its construction, making it a good choice around corrosive chemicals, sensitive electronics or wherever a nonmetallic path is preferred.

Being fully nonmetallic, it always requires a separate equipment-grounding conductor inside. It comes in a few types with different core constructions, has temperature and length limitations, and needs fittings listed specifically for LFNC to keep the liquidtight seal intact.

When it applies

Liquidtight flexible nonmetallic conduit is the all-plastic flex you reach for on wet, corrosive, or vibrating connections where you do not want metal. It shines on the last stretch to a motor, a rooftop unit, or a piece of equipment that shakes, letting the conduit absorb movement while sealing out moisture.

Common mistakes

• Running excessively long lengths where the type is only meant for limited runs unless specifically listed otherwise.
• Forgetting the equipment grounding conductor, since the nonmetallic conduit provides no ground path.
• Using fittings not listed for the conduit, which breaks the liquidtight seal at the connection.

In the field

On a vibrating pump I leave a gentle service loop of LFNC rather than a taut run. The flex takes the movement, the seal holds, and the terminations do not slowly work loose.