joltes@husc9.harvard.edu (Richard Joltes) (09/28/90)
I'm tired of digging for this information. This may not be the best forum for my question, but here goes. Where can you find the safety specs pertaining to cable type & insulation (i.e. teflon vs. PVC) and applications of each? I've been told that teflon "is required in any situation where the cable passes through a supporting or fire abating wall or floor" but can't find the source for the specs. Does anyone know what the specs are, what book/publication they're in, and how I can get a copy? Thanks in advance. Please post directly to me and I'll summarize to the net if there's interest. Dick Joltes joltes@husc9.harvard.edu Mgr. of Hardware & Facilities Harvard University Science Center
kwe@buit13.bu.edu (Kent England) (09/28/90)
In article <4277@husc6.harvard.edu> joltes@husc9.harvard.edu (Richard Joltes) writes: > >Where can you find the safety specs pertaining to cable type & insulation (i.e. >teflon vs. PVC) and applications of each? I've been told that teflon "is >required in any situation where the cable passes through a supporting or fire >abating wall or floor" but can't find the source for the specs. Does anyone >know what the specs are, what book/publication they're in, and how I can get >a copy? > So called "low voltage" data cable is included in NFPA fire codes along with electrical wiring and both are covered in the NEC. The fire code regulations are determined by each individual state and municipality. Even though I can throw a rock thru your window (figuratively speaking) the fire code over here in Boston bears no necessary relationship to the code in Cambridge. But most state and local codes are based on the National Electrical Code (NEC) and the National Fire Protection Agency (NFPA) has input to that. I once spent several days trying to track down all the references to low voltage cable in the Mass code (1987) and gave up. It is literally impossible to track all the references and most references are vague and unclear. There are new regulations since then that have been promulgated by the NFPA, but I don't think they are yet in the NEC or any state codes. At any rate, the final arbiter is the inspector, so you need a knowledgeable general contractor who can assure you that what he plans is to spec for your situation and even then you can't be sure. Given all that, in general, if cable is in space that is not defined to be environmental air space, it can be PVC. If it is environmental air space, it must be fire rated and that means teflon. An example of environmental airspace is room space. Another example is air plenum, like an above ceiling space used for wiring and ventilation. An exception has been made in the Boston code for plenum space that is wired with smoke detectors that shut down fans when smoke is detected. With the smoke detector, PVC is allowed in above ceiling space in Boston. Skyscrapers may be subject to other regulation. I disclaim all responsibility for the above interpretations. I am not qualified to render more than opinion on the above. Seek the guidance of qualified contractors and inspectors before installing wire. Don't try this at home. --Kent
knight@mortal.enet.dec.com (Paul Knight) (09/28/90)
In article <65129@bu.edu.bu.edu>, kwe@buit13.bu.edu (Kent England) writes: |> In article <4277@husc6.harvard.edu> |> joltes@husc9.harvard.edu (Richard Joltes) writes: |> > |> >Where can you find the safety specs pertaining to cable type & insulation (i.e. |> >teflon vs. PVC) and applications of each? |> > |> So called "low voltage" data cable is included in NFPA fire |> codes along with electrical wiring and both are covered in the NEC. |> |> But most state and local codes are based on the National |> Electrical Code (NEC) and the National Fire Protection Agency (NFPA) |> has input to that. |> Okay so far... The NEC can be ordered from: The National Fire Protection Association (NFPA) 1 Batterymarch Park Quincy, MA 02269 1-800-344-3555 I believe there are several volumes, so you'll probably want to check with the NFPA to determine which ones you need.. Perhaps a better source for your purposes is the "BICSI Telecommunications Distribution Methods Manual" from the Building Industry Consulting Service, International (BICSI). The 1989-1990 price is $72 for members and $179 (gulp) for non-members. Order from: TESTMARK Laboratories Publications Department 3050 Harrodsburg Road Lexington, KY 40503 (606) 223-3061 (my source says to make checks payable to "GTE Supply Inc." |> Given all that, in general, if cable is in space that is not |> defined to be environmental air space, it can be PVC. If it is |> environmental air space, it must be fire rated and that means teflon. okay... except that PVC and Teflon(tm) are not the only types.. |> An example of environmental airspace is room space. No No No! You can use PVC in offices, rooms, etc. There has been some discussion of not allowing it for computer rooms, however. I'm not sure of the status in computer rooms now. |> Another example |> is air plenum, like an above ceiling space used for wiring and |> ventilation. If you have a suspended ceiling with air grills (for return air) which open into the space above the ceiling (plenum), then the entire plenum is environmental airspace classified as "other". You have to use plenum-rated wiring here. (This must be marked CL2P - this is often Teflon(tm), but other formulations are available.) If you have a suspended ceiling with BOTH supply and return air ducts, then the space not in the ducts is non-environmental airspace. You MAY be able to use general building wiring (CL2 - often PVC) in this space, but many local codes vary. In NO CASE can you run cables through air ducts. Your best rule of thumb is to use CL2P for any behind-the-wall or over-the-ceiling wiring. |> |> I disclaim all responsibility for the above interpretations. Seek the |> guidance of qualified contractors and inspectors before installing |> wire. |> |> --Kent Me too. - Paul Knight - DEC Networks and Site Services
kwe@buit13.bu.edu (Kent England) (10/03/90)
In article <1990Sep28.093731@mortal.enet.dec.com> knight@mortal.enet.dec.com (Paul Knight) writes: > [I said:] >|> An example of environmental airspace is room space. > >No No No! You can use PVC in offices, rooms, etc. There has been some >discussion of not allowing it for computer rooms, however. I'm not sure >of the status in computer rooms now. > Environmental airspace is space where people work and breathe. This refers to offices, labs, and hallways. If you have open ceiling labs with exposed cabling or open ceiling hallways with cable trays, then your cables are in environmental airspace and are subject to low smoke emission restrictions. This applies in "room space" by any interpretation of the term. It is true that cables that attach devices to the building cabling system are not included in current codes. This may change. I know that furniture is included in some fire codes, but, of course, not in the electrical part of the spec. Computer rooms are very dangerous places to be in a fire. Cables are usually not fire rated, and they are usually installed in "plenum space" where ventilation would force toxic smoke out from under the floor and into space where people breathe. I expect computer rooms to come under low smoke regulation at some future time. > >In NO CASE can you run cables through air ducts. > Did I say that? It is something you need to watch your contractors for. >Your best rule of thumb is to use CL2P for any behind-the-wall or >over-the-ceiling wiring. Except that someone may challenge that assumption and you might save a lot of money doing it in other ways without losing fire safety. I did not mention conduit. Conduit, while expensive, is useful in many situations. For example, if you are using trunk cabling that does not need to meet spec in exterior ducts, you can bring it in from the street into your riser system in steel conduit, providing good physical protection and compliance with fire codes. Another thing I did not mention is firestop integrity. When installing cable (low smoke or otherwise), you must be sure to maintain the integrity of the firestops and firewalls designed into your building. We design our network closets with all four walls as firestops, with double drywall from structural floor to structural ceiling. The entire riser system is one fat fire rated conduit. We don't need low-smoke compliance in our risers, but we do need to maintain the firestops and that means capping all unused sleeves that penetrate firewalls, and filling all used sleeves with a suitable firestop material. This is especially important during retrofits. You must not punch big holes in firewalls- you should install sleeves with tight seals around the outer perimeter and either caps or firestop in the sleeves. Especially important is firestopping vertical sleeves in your riser. Don't use slots. They are easy to pull cable thru but hard to firestop. In general, remember what the fire code designers are trying to do: First, inhibit the spread of fire. Second, ensure a safe period during which people can safely evacuate a burning building without injury or poisoning. Firestops help retard the spread of a fire. Low smoke cabling ensures that during the period before flashover (when anyone left in the area would die anyway), people can escape without being burned or poisoned by inhaling toxic emissions from burning cabling that is in their environmental airspace. You do not want to find yourself in the position of contributing to the unnecessary deaths of people from toxic fumes. And another thing: in retrofits, make sure that your contractors don't block fire exits while working or leave ceiling tiles misplaced during off hours. These sorts of mistakes also contribute to dangerous conditions during fires by disrupting airflows and blocking egress. It sometimes seems to me that every contractor thinks that stairwells are the best places to store materials and prepare construction materials. Don't let them do it. Far better to disrupt the office space than to block the exits. Again, you don't want to find yourself responsible for unnecessary deaths or injury. I wish I could give you the cookbook on fire safety, but with some practice and experience you should find a simple set of standard procedures that will do the job. Just remember that the fire rating of the cable is but one part of fire safety as it related to low voltage building cable distribution systems. I guess that is enough. Who wants this soapbox next? :-) --Kent
imp@jhereg.osa.com (Charles T. Lukaszewski) (10/09/90)
As a company that installs networks for a living, we couldn't agree with Kent more on this issue. It is critical that anyone putting in cabling for the first time or as a retrofit understand the issues involved, and Kent has summarized pretty well. I'd like to add one other thought to the discussion. In many localities, older structures are accorded a certain amount of "immunity" from present fire codes. As has been pointed out, ultimate authority rests with your local fire marshall - if you aren't sure about something, check it out. However, in one particular heavy manufacturing environment that we work in, a large (over 4,000,000 square feet) plant is substantially exempt from such codes. Nevertheless, the dangers posed by fire are the same, and we have opted to install all twisted pair, fiber and coax according to Code. At OSA we see the exemption issue a lot. It is usually a judgment call you have to make based on the site and the dangers involved if fire were to break out. However, I would urge everyone to err on the side of caution, which frequently is not the cheapest option. _______________________________________________________________________________ Charles T. Lukaszewski imp@osa.com 612 525-0000 Managing Partner & Chairman Open Systems Architects, Inc. "Who needs a disclaimer? I liked the opinions so much, I bought the company!" -- _______________________________________________________________________________ Charles T. Lukaszewski imp@osa.com 612 525-0000 Managing Partner & Chairman Open Systems Architects, Inc. "Who needs a disclaimer? I liked the opinions so much, I bought the company!"
gary@dgcad.sv.dg.com (Gary Bridgewater) (10/13/90)
In article <1990Oct8.215428.4192@jhereg.osa.com> imp@jhereg.osa.com (Charles T. Lukaszewski) writes: >... >At OSA we see the exemption issue a lot. It is usually a judgment call you >have to make based on the site and the dangers involved if fire were to >break out. However, I would urge everyone to err on the side of caution, >which frequently is not the cheapest option. For giant buildings this may be an issue but for the more common case of a small or medium size site I wouldn't be too sure. High grade, high quality cable can be cheaper over time since it will have less tendency to kink or abrade and/or be less affected by such problems. Also, if you move or reconfigure then you never have to worry or replace the cable if it goes from non-plenum to plenum or even exposed in floor runs. We recovered cable that had been run over the roof in a pipe and left for two years. It took a cable pulling engine to string and to remove and when it came out it looked and acted new. We could have bought cheaper cable - both times - and 'saved' money twice instead of being profligate once and getting two runs for the price of 1.4 or so. -- Gary Bridgewater, Data General Corporation, Sunnyvale California gary@sv.dg.com or {amdahl,aeras,amdcad}!dgcad!gary C++ - it's the right thing to do.