Monday, April 21, 2003 @ 11:20:21 PM Central Standard Time PM> It's due to fire code and NEC (National Electric Code.) Even low voltage PM> cables have the potential (no pun intended) of starting fires. The thing is PM> that you never know what the failure mode of the box it's hooked up to will PM> be -- if a computer suffers AC death syndrom and puts 120VAC on the ethernet PM> cable, it could be a bad thing. Also, not just hardware failure is the concern. Non-Plenum should be run through conduit. Plenum is made for use without conduit (like Romex for electrical) due to fire retardant/non-toxic-burn coating, and it's a little more bad ass in nature, as mentioned earlier. If you had non-plenum cables running through out an office building/multiple floors not in conduit (just hanging above drop ceilings, through vent. ducts, between walls, etc..) and a fire breaks, your entire network cabling can act like a big fuse. Say a coffee maker starts on fire (cause unknown), and a pc is next to it. The coffee maker burns (unnoticed)and starts the pc on fire. Someone sees the burning coffee maker/pc & rushes to grab a fire extinguisher. The pc burns and your cost-cutting non-plenum haphazardly wired cat 5 cable starts to burn. The employee returns with a fire extinguisher, and puts out the fire, or so he(or she) thinks. While the employee was franticly trying to put out the small blaze, the flame started moving down along the non-plenum cable, and secretly burned it's way into the wall, where the cable drops down two floors into an old wiring closet. This would have been a small stupid fire, and contained had the proper cable been installed. As it burns its way down the cable, it is having a great time igniting anything flammable in its path (and kicking out some Saddam Approved toxic gas too). You can imagine how the story goes from there. Death & destruction to all in it path, and then it reaches the wiring closet. When burning starts in the closet, it ignites all the other el-cheapo cables in their, and the process of burning up or down the cable begins again. Oh no!!!(terror strikes) You ran a non-plenum cable from the main closet threw a sewer across the street to your other buildings closet. and boom....another towering inferno. Here is a more proper def: Commercial constructions often use suspended ceilings as return passages for environmental air. These "plenum" spaces have become convenient wiring locations for a variety of applications. However, use of these areas may pose a serious hazard in the event of a fire. Once the fire reaches the plenum space, few barriers exist to contain the smoke and flames. The National Fire Protection Association (NFPA) has recognized the potential for a hazard created by wire and cable in an environmental air space. Severe restrictions on cabling were included in the 1975 edition of the NEC. All following NEC editions set forth safety requirements for flammable insulations. The National Electric Code (NEC) states that all cabling not in conduit, installed in plenum spaces, shall be listed as having adequate fire-resistant and low smoke-producing characteristics. Rock-On, Robert (aka B_o_B) David Felix De Mars West Longitude 90' 15' 43" http://b-o-b.homelinux.com mailto:chewbaka at toughguy.net _______________________________________________ TCLUG Mailing List - Minneapolis/St. Paul, Minnesota http://www.mn-linux.org tclug-list at mn-linux.org https://mailman.real-time.com/mailman/listinfo/tclug-list