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RicodJour[_2_] RicodJour[_2_] is offline
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Default NEC question: low-voltage wiring crossing 120v wiring.

On Sep 29, 10:43*pm, wrote:
On Thu, 29 Sep 2011 17:07:32 -0700 (PDT), RicodJour









wrote:
On Sep 29, 5:30*pm, wrote:
On Thu, 29 Sep 2011 15:19:42 -0400, "Percival P. Cassidy"


wrote:
I am running network cables *-- shielded, if that makes a difference --
above suspended ceiling where there is already 120V Romex wiring in
places. This 120V wiring is stapled to the joists at intervals.


Is it OK for the network cables to lie on the ceiling support members,
and thus beneath the Romex? Or should the network cables be above the
Romex? Or should one or both be in conduit? -- more precisely, should
what is now Romex be redone with individual conductors in conduit?


*no issue even with cat5 or cat5e non sheilded - as long as your space
above the ceiling is not an air plenum - and then you just need plenum
rated cat5


What's the reasoning behind plenum rating a computer cable? *Is there
some fire-reasoning behind it or what? *What's the difference between
rated and non-rated cable?


R


Fire rating. Plenum cable will not support combustion when flame is
removed - will not flame on it's own - and different smoke. Non-plenum
rated is not allowed in an air return.


Yes, but my question was whether the OP's above-ceiling space is
actually a plenum. I had assumed the question was residential, a
basement and the space was not used for airflow. Granted, that's
reading a lot into it, but perhaps they were bad assumptions.

Here are some interesting (but boring!) videos of the different cable
ratings burning.
http://www.l-com.com/multimedia/vide....aspx?ID=13100
Quite a difference between plain vanilla PVC and rated cable.

R