CAT-5 Plenumvs. PVC

[Doug Ivers]

I have noticed that the Plenum cable is 3-4 times more expensive than the
PVC cable. In a 100 MHz network with 4 computers and runs of less than 75
feet to the hub would I see any benefit with the more expensive cable?

Doug

[Samy E]

No.
The "plenum" feature relate only to the toxity of the smoke generated
when the cables burn (they are less toxic than "pvc").
i.e. if you want to put Cat-5 cables inside your air-conditioning
ducts (although I have never seen anyone crazy enough to do it), then
you better have the "plenum".

For all other practical purposes, use PVC. There is NO difference in
terms of network performance. Same electrical characteristics.

[Stuart Robinson]

No benefit at all, apart from greater safety.

But its use is mandatory in plenum spaces (false ceilings and the like) in
most, if not all, US States.

Dont know where else its mandatory, but its not in the UK

Stuart.

Mail me on srnet at cix full stop co full stop uk

[J. Clarke]

Just to clarify, a false ceiling is not a plenum unless it's used as a flow
path in the air conditioning and ventilation system.

Occasionally it's also used to allow a difficult pull that can't be
accomplished with pvc--the plenum cable has teflon insulation which is more
slippery so it can be pulled in situations where the friction generated by
PVC causes the cable to bind up halfway along.

--

--John

Reply to jclarke at eye bee em dot net.

Stuart Robinson wrote in message ...

[Stuart Robinson]

> Just to clarify, a false ceiling is not a plenum unless it's used as a
> flow
> path in the air conditioning and ventilation system.

Indeed, but most of us network types are not building experts, so its
sensible to assume a false ceiling is a plenum unless you specifically
know otherwise.

And what happens when ventalation/aircon ducts are left open in the false
ceiling, as I have seen one older building with retro fitted false
ceilings ?

[J. Clarke]

Stuart Robinson wrote in message ...

>> Just to clarify, a false ceiling is not a plenum unless it's used as a
>> flow
>> path in the air conditioning and ventilation system.
>
>Indeed, but most of us network types are not building experts, so its
>sensible to assume a false ceiling is a plenum unless you specifically
>know otherwise.

Not that hard to tell in most cases. When you've got the ceiling tiles down
you can see how the ducting is routed. If there are ducts going to all
vents then it's not a plenum. If there are any vents that are just an open
grid then it's a plenum. If you're not sure, then you do no harm to
anything except the client's wallet by pulling plenum. But you do do harm
to your reputation when the next guy to come in says "Why in the Hell did
they use all this unnecessary plenum cable?".

>And what happens when ventalation/aircon ducts are left open in the false
>ceiling, as I have seen one older building with retro fitted false
>ceilings ?

If the ducts are used as part of the flow path then the false ceiling is a
plenum. If they're blocked off it's not. What makes it a plenum is that it
forms part of the flow path, not the presence of particular hardware. But
it's probably best to talk to the inspector in that case.

>
>
>Stuart.
>
>Mail me on srnet at cix full stop co full stop uk

--

[Stuart Robinson]

Thanks for the explanation, filed for reference.

Where I work, in the UK, there is no general requirement to use such
cables (yet).

[Tim Andaya]

Another factor to look into which is not usually a problem in small networks
is the cable rating on your Cat5 wire; their are two types of installations.
Horizontal and vertical. A horizontal installation is a single floor
installation (up wall across ceiling is till single floor) and a vertical
installation includes at least one run between floors (first floor lobby to
second floor bathroom, whatever).
If you are doing an installation that is single floor, you can use type "CM"
wire, if you are doing a multi-story installation, be sure your wire is type
"CMR".
I have found that there doesn't seem to be a real price difference with
respect to this rating, but the "CMR" specification has to do with the cable
constructs ability to resist stretching from its own weight.
As far as the plenum rated wiring is concerned, it is safer to err on the
side of safety, if you are running cable in a concealed, open space (attic,
crawl space, duct, etc.,), you would do better to run plenum rated cable for
peace of mind than for any other reason. Inspectors may make you run plenum
anyway so if you are doing a commercial installation. Do it right the first
time and include it in the price of your installation.

[albertasen]

Hello everyone, i am albertasen. I would prefer PVC because it is less expensive than CAT-5 Plenumvs and more attractive than CAT-5 Plenumvs. It needs less care, easily installable etc. Madaanindia is expert in PVC.