Installing innerduct

Q: I am a manufacturer`s representative for various network products. There seems to be some confusion with almost everyone I speak to regarding the use of fiber-optic innerduct inside a building. Should it be made of polyvinyl chloride (pvc) or polyethylene (PE), riser-rated or plenum? Does the National Electrical Code (nec) or Telecommunications Industry Association (tia--Arlington, VA) have a specification or recommendation? Please let me know what I should recommend to my customers.

Q: I am a manufacturer`s representative for various network products. There seems to be some confusion with almost everyone I speak to regarding the use of fiber-optic innerduct inside a building. Should it be made of polyvinyl chloride (pvc) or polyethylene (PE), riser-rated or plenum? Does the National Electrical Code (nec) or Telecommunications Industry Association (tia--Arlington, VA) have a specification or recommendation? Please let me know what I should recommend to my customers.

John Iapalucci

jpi Associates

Wake Forest, NC

A: First, tia is no help here; this is a life-safety issue. The tia standards address performance specifications only, referring the reader to the applicable electrical code for other matters. For a list of the applicable electrical codes in your state, go to www.bicsi.org/govern.htm.

Second, you`re not alone in your problem. I have received numerous inquiries regarding innerduct that has been installed in plenum and riser spaces in nursing homes, hospitals, and school buildings. Each inquirer is seeking vindication for his or her particular point of view--owners and end-users are blaming installers and contractors, who are blaming distributors. Their number one concern is: Who is going to pay to have all that polyethylene innerduct removed?

Most are puzzled when I ask if they know what the only difference is between the jacket on innerduct and that on outside-plant cable. They don`t make the connection: The only difference is the color. Carbon black is added to the polyethylene of the cable jacket for ultraviolet-light protection, while innerduct can be ordered in a rainbow of colors, even with stripes.

The source of the confusion is semantic. Innerduct is mentioned only once in the nec, also known as nfpa 70-1996. Section 770-5 cautions that "plastic innerduct commonly used for underground or outside-plant construction may not have appropriate fire-safety characteristics for use as an optical fiber-optic cable wiring method within buildings."

What`s being installed is an optical-fiber raceway system. nfpa 70-1996, Section 770-5, says an optical-fiber raceway system is designed for enclosing and routing only nonconductive optical-fiber cables and requires that the raceway be of a type permitted in Chapter 3 or a listed optical-fiber raceway.

nfpa 70-1996, Section 770-51(e), requires that plenum optical-fiber race-ways be listed as having adequate fire- resistant and low smoke-producing characteristics, and Section 770-51(f) requires that riser optical-fiber raceways be listed as having fire-resistant characteristics capable of preventing the carrying of fire from floor to floor. There is no mention of nonmetallic communications raceway, which would be the same as an optical-fiber raceway--except for communication cables.

But that, too, will change. I read in a recently published Report on Proposals that the National Fire Protection Association (nfpa--Quincy, MA), which maintains the nec, will modify the forthcoming edition of the nec--nfpa 70-1999--especially in Section 800-51(j), (k), and (l), to address plenum, riser, and general-purpose communications raceway.

Until nfpa 70-1999 is published, my best advice is: Do not install any raceway inside a building that`s not listed for the purpose particular to that area--plenum, riser, or general.

One nice lady from a school district in the Midwest asked, "Why would someone knowingly put polyethylene in a plenum or riser?" The answer is "money." If an inspector doesn`t catch the "mistake" during the construction and inspection phases, who would be the wiser? Unless, of course, there is a fire.

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