Rosslyn, Va.-based National Electrical Manufacturers Association (NEMA) has published RV 3-2010, "Application and Installation Guidelines for Flexible and Liquidtight Flexible Metal and Nonmetallic Conduits." The standard was 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.
"Users of the new RV 3 will certainly benefit from having a convenient and concise reference guide to all articles of the National Electrical Code (NEC) relevant to LFNC wiring systems," says Fred Small, chair of the 5TC Section. "Even more important, though, these guidelines cover critical installation aspects of LFNC that help ensure that the mechanical and electrical integrity of the wiring system is maintained. The industry is looking forward to seeing this information being made available to the installers and Authorities Having Jurisdiction."
RV 3 may be downloaded at no charge, or a hardcopy purchased for $85, by visiting www.nema.org/stds/rv3.cfm.