The National Electrical Manufacturers Association (NEMA) has published RV 3 “Application and Installation Guidelines for Flexible and Liquidtight Flexible Metal and Nonmetallic Conduits”, a standard last published in 2006.

Before this newest revision, RV 3 only contained guidelines for
liquidtight flexible metal conduit (LFMC). Through a cooperative effort
of NEMA’s Flexible Metal Conduit Voting Classification (7WC-1) and
Polymer Raceway Products Section (5TC) Technical Committee, liquidtight
flexible nonmetallic conduit (LFNC) guidelines were added.

The new guidelines for LFNC cover general construction aspects, such as
available trade sizes and conduit materials and surfaces, as well as
grounding, marking, and codes and standards. Guidelines on LFNC fittings
are also addressed in detail, covering fitting selection, environmental
considerations, marking, grounding and installation considerations
including conduit preparation, assembly torque, assembly technique, and
attachment to boxes or enclosures and support systems.

CLICK HERE for RV 3.

CLICK HERE for NEMA.