PVC vs Plenum

[Ameritel]

I heard something yesterday that I have not heard in 25 years. Another cable contractor said that using plenum cable (cat 6) in underground EMT will breakdown within a year or so to where it is not usable and that PVC was better. I do know that gel filled Alpeth is the recommended method (costly)but have never heard about the Plenum breakdown. Has anybody?

 

[EV607797]

Not only have I heard of this, but I've seen it many times. It is also not resistant to sunlight and will break down in no time if used outside. Just like with electrical wiring, there is always the proper and improper material to be used for the application. Personally, I wouldn't use anything but filled cable in an underground conduit.

 

[JDBrown]

Whoa. I'd never heard of this. Is this only a problem for plenum cable in underground EMT? Or does it happen in EMT installed in walls or ceilings? Does it happen to plenum cable in underground PVC? I ask because a certain government entity I work with requires ALL CAT5/6 cables to be plenum rated, regardless of where they're installed.

 

[EV607797]

It has more to do with the exposure to water that seems to always collect in underground conduit. The plenum jacket isn't designed for exposure to anything that would not be present in a standard plenum environment. Sunlight and water are certainly not found in them.

 

[hbiss]

I ask because a certain government entity I work with requires ALL CAT5/6 cables to be plenum rated, regardless of where they're installed.

What do you expect from the government, competence or something? As long as it costs more and taxpayers pay for it it must be better.

-Hal