Fire test for flame tranvel and smoke of plenum cables. origin and considerations

摘要

In the later 1970's a fire test was invented, using a traditional test apparatus for building products, the Steiner tunnel, to list data and communication cables for use in plenums, without requirement enclosure in metal conduit. Once this became part of the NEC, plenum cables had to have fluoropolymer materials for both insulation and jackets. The code change came about as a result of the search for greater ease of installation and new applications for cables with exceelent fire performance. The rapid increase in use of communications tools, such as computers, has meant fast growth in this industry. The late 1980's saw vinyl materials capable of replacing fluoropolymers as coating materials, and the 1990's saw the use of plyolefins, as partial or total replacements of fluoropolymers, mainly of primary insulation. All of this caused extensive codes and standards activity around the test, in the USA and internationally, including proposals to replace it by alternative means of approving plenum calbes. It is not clear, at present, whether fire safety problems actually exist with plenum cable.