Q: My cable installer has penetrated several concrete masonry fire walls (4-hour, F-rated), and I suspect that the installation is not up to standard. My problem is that I do not know what the standards are for this type of installation. The installer presented me with a page from the bicsi (Tampa, FL) Telecommunications Distribution Methods Manual (tdmm), Issue 7, Chapter 20, page 20. At the top of the page, a drawing shows a cross section of an installation involving polyvinyl chloride (PVC) innerduct, which houses the fiber. The drawing shows firestop material inside the innerduct--between the innerduct and firewall--and some sort of sleeve around the innerduct.
My installer placed firestop material between the innerduct and firewall, without a sleeve or any firestop inside the innerduct. I have insisted that a sleeve is required per the tdmm drawing; however, he assures me that the sleeve shown is not actually a sleeve, but rather a continuation of the firestop around the innerduct. My question to him was, "Why does the drawing show two arrows that point to different firestop materials?"
We are at loggerheads over this issue. I suspect that he is protecting his interest because, if I am correct, he will have to rework a large number of penetrations. I am concerned because my department has the liability for the firewalls, and we certainly want to be safe. Can you tell me where I can locate a definitive standard regarding these penetrations?
John R. Allen, Project Manager
CharBroil div. of W.C. Bradley
Columbus, GA
A: I applaud your efforts in seeking a written standard or code to resolve this issue. Whether the firestop installed by the contractor is code-compliant is the decision of the authority having jurisdiction (AHJ). And the code that the AHJ looks for compliance with is the one adopted by your local and state municipality.
Although it is an excellent methods manual, bicsi`s tdmm is not a code or standard. In tdmm Issue 7, Chapter 20 (top of the page), the conduit penetration through concrete, masonry wall or floor shows a metal pipe or conduit. The diagrams on page 21, however, show firestopping PVC innerduct penetrations; no metallic sleeves are shown.
Innerduct is a raceway, and is not considered a conduit. The 1996 National Electrical Code (NEC) defines raceway as "an enclosed channel of metal or nonmetallic materials designed expressly for holding wires, cables or busbars."
Raceways include almost everything; for example, rigid metal and nonmetallic conduit, intermediate metal conduit, liquid-tight flexible conduit, flexible metallic tubing, flexible metal conduit, electrical metal and nonmetallic tubing, underfloor raceways, cellular concrete floor raceways, cellular metal floor raceways, surface raceways, wireways, and busways.
What the NEC defines as electrical nonmetallic tubing is commonly known in the telecommunications industry as innerduct.
There may be several methods for firestopping electrical nonmetallic tubing. The one I am familiar with is intumescent wrap strips but, to my knowledge, these cannot give you a firestop system with an F (fire) rating of 4 hours on a concrete wall assembly that is penetrated with a plenum-rated electrical nonmetallic tubing.
Not all innerduct is created equal; that is, there are specific types for specific tasks. In the NEC, section 770-5, optical-fiber raceway system, the FPN (fine-print note) states 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."
Polyethylene innerduct is not rated for any level of flame retardance and should never be used in a building, cable vault or other location where fire hazards exist or where building codes and electrical codes require low flame spread, low smoke density and high oxygen-index-rated raceways or conduit.
Other products are available, such as pvdf (polyvinylidene, or Halar) electrical nonmetallic tubing, that are UL-listed plenum raceways meeting the UL standard 2024 and complying with NEC Article 770 for fiber-optic raceways. However, using a plenum-rated innerduct does not eliminate the need for plenum-rated cables
Donna Ballast is a communications analyst at the University of Texas at Austin and a Bicsi registered communications distribution designer (Rcdd). Questions can be sent to her at Cabling Installation & Maintenance or at PO Drawer 7580, University of Texas, Austin, TX 78713; tel: (512) 471-0112, fax: (512) 471-8883, e-mail: [email protected].