Gary Lampe, distribution systems engineer at Norstan Communications Inc. (Des Moines, IA), comments:
Regarding the "Firestopping fiber-optic cable penetrations" article [by Dan Silver of 3M, November 1995, page 56], I question the use of polyethylene innerduct inside a building.
Matthew Fagan, senior public relations representative at 3M Austin Center in Austin, TX, responds:
You make a good point. Typically, polyethylene is not used inside a building, and 3M is not recommending its use. We recommend that installers follow local building codes.
What we are saying is that you can fire-protect polyvinyl chloride or polyethylene innerducts, regardless of the circumstances. For example, we are aware of an occasion where several thousand feet of polyethylene innerduct were mistakenly installed during a building wiring job and then had to be replaced.
Different plastic building materials have advantages and applications in different situations. Accordingly, they have different characteristics in a fire.