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North American Network Operators Group

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Re: CAT5 surge/lightning strike protection recommendations?

  • From: Frank Coluccio
  • Date: Wed Sep 14 10:53:35 2005

There's not much left to interpretation and preferences here, aside
from the choice of medium to be used. I should also add that some of the
advice that has been posted in this thread, as well-meaning and thoughtful as it
has been, has been downright dangerous to follow.

If one is going to run copper cable between buildings, or outdoors, in
general, in lieu of the better alternatives of fiber or wireless, then
there are local and national electrical, fire and safety codes in effect
that spell out what you must do, enforceable under the penalty of law.
And while certain of those precautions have been spelled out upstream in
piecemeal fashion, none thus far has been entirely accurate or complete.

Yes, when running copper between buildings, lightning arresters/circuit
- i.e., protection - are a must, but they must be placed within a couple
of feet of the building point of entry, or POE. Think about it. Does it
make great sense to protect a cable from surges deep within the interior
of a building if the cable traverses vast distances on premises
unprotected between the point of entry and the terminal point.
Therefore, the stipulation of performing grounding, bonding and surge
protections at the point where the cable enters the building (in
potentially at addition points, elsewhere, when required).

Also, if the copper cable is "armored" with a corrugated steal jacket,
as many outside plant cables are, then the shielding (the armor) must
also be "bonded" to earth ground at the POE, as well. So the issue
becomes one not only of grounding, but bonding, as well. And while I'm
on that subject, be aware that many FIBER OPTIC cables designed for
inter-building/outside plant use are also armored and must be treated in
the same manner.

BICSI (Building Industries Consulting Systems International)
www.bicsi.org does a good job of rolling up all of the relevant
standards, as do a number of other sources. For some good coverage of
safety, grounding and bonding principles and techniques see the
following Structured Cabling Supplement reference by Panduit (taken from
the Cisco CCNA Networking Academy Program)

http://www.tecmiami.com/cisco/extra/CCNA1_CS_1_en.pdf 

Frank A. Coluccio
DTI Consulting Inc.
212-587-8150 Office
347-526-6788 Mobile




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