Smurf tube is corrugated PVC flexible tubing used to provide an easy method of upgrading structured wiring systems. The tube is run from the distribution panel to each outlet during the prewiring construction phase. Retrofit wiring can easily be pulled through the tubes without painstaking cable snaking. The most common type, Flex-Plus Blue ENT, is manufactured by Carlon, Cleveland, Ohio. Workers nicknamed it “smurf tube” because of its distinctive blue color.
**Why can’t ENT be installed outdoors? **
ENT was designed as an in-building product (see Article 362 of 2002 NEC). Since ENT does not have ultraviolet (UV) inhibitors added to the PVC compound such as our rigid PVC conduit, it is more affected by the ultraviolet rays from the sun. We know from experience that unprotected outside storage of ENT may result in brittleness in a 3 to 4 month period. ENT from the factory is stored with a white plastic wrap for storage and shipping to protect the product from the sun.