Help finding building code guidlines for Network and Telephone wiring.

The cabling installation is going to be governed by an electrical code. In VA it is the National Electrical Code in particular. The best strategy would be to call your municipality (your project location's municipality rather), get through to the fire marshal?s office and ask them what edition of NEC their inspectors have for field use. The NEC 2005 has just been published (publishes every three years), but inspectors would not use the most recent edition. Sometimes it's even still 1999 edition. Then you can go online (Amazon?) and get yourself a copy.

Why would you assume you need plenum ?

Robert,

Many jurisdictions use the National Electrical Code, and in that publication Article 800 covers both telephone and ethernet cabling safety practices.

Your local Building Department can tell which codes are used in your city.

If the NEC is used, then you need to read Article 300.22, which covers "other spaces handling environmental air", which is how drop ceilings are described in the NEC. When in doubt, however, use plenum rated cable, which should be marked CMP.

Robert R Kircher, Jr. wrote:

David,

Our basement has a drop ceiling, but I don't think it is handling environmental air. Our HVAC ducts do that, both ways. I am a bit confused by this provision in 300.22(c) as to why I wouldn't be allowed to run NM cables along the long side of the joists, but perpendicular would be o.k. What does "environmental air" exactly mean? There is air between the joists (as opposed to insulation), but what makes it environmental? The original wiring I have there is all NM, but it is also 28 years old. Where can I find some more clarifying information? I have the Illustrated Guide to the NEC 2002, but it sheds no light on what "handling environmental air" does and does not mean. I don't want to go through the hassle of installing conduit, but I don't want to fail inspection either.

Thanks,

Thomas

David R. Miller wrote:

covers

The term "environmental air" can be loosely defined as air that is circulated/recirculated for controlling the environment of a space. If the air above the dropped ceiling is cycled through the HVAC, then it is environmental air. If it is static, that is not circulated, then it is not evironmental air.

As you have stated there are ducts in your ceiling that bring in heated/cooled air and other ducts that return air to the HVAC system, then the air above the ceiling, in your case, is not considered environmental. Is the mud a little less opaque?