I have a bunch of cat5 buried about 1 ft below the surface connecting multiple
buildings on a campus (short runs) and lightning strikes nearby have caused
surges along one or more of the cables and burnt out switch ports. I would
like to protect the switch ports -- there seem to be lots of products on the
market.
Anyone have recommendations (tested/practical is best :-)?
The APC Protectnet PNET1 and PRM24 seem quite nice and not too expensive --
if they work....pros? cons?
Thanks,
Adi
Fiber would be my choice. Not only will it solve the lightening strike
problem; you will not have to worry about
ground potentials being different on each side of the cable run.
James
Routing and Security Administrator
At the Santa Fe Office: Cyber Mesa Telecom
jamesh@cybermesa.com noc@cybermesa.com
http://www.cybermesa.com/ContactCM
(505) 795-7101
I have a bunch of cat5 buried about 1 ft below the surface connecting multiple
buildings on a campus (short runs) and lightning strikes nearby have caused
surges along one or more of the cables and burnt out switch ports.
Don't do that, then.
I would like to protect the switch ports -- there seem to be lots of
products on the market.Anyone have recommendations (tested/practical is best :-)?
Use the cat5 as a pull rope, install fiber.
The APC Protectnet PNET1 and PRM24 seem quite nice and not too expensive --
if they work....pros? cons?
Seriously, this is a battle against Mother Nature that you aren't going to
win. Differences in ground potential as well as induced currents into the
UTP will continue to cause equipment failure as well as possibly kill you
or someone else.
I have a bunch of cat5 buried about 1 ft below the surface connecting
multiple
buildings on a campus (short runs) and lightning strikes nearby have
caused
surges along one or more of the cables and burnt out switch ports. I would
like to protect the switch ports -- there seem to be lots of products on
the
market.Anyone have recommendations (tested/practical is best :-)?
The APC Protectnet PNET1 and PRM24 seem quite nice and not too expensive
--
if they work....pros? cons?
Adi,
Is there a reason that your between-building runs aren't being done with
Fibre?
It being non-conductive is one immediate advantage....
Also if your grounding is inadequate you may like to take a squiz at the
ISO or TIA Standards as they pertain to cabling.
In NZ we have a variety of standards which all point back to ISO, the ANSI
equivalents are TIA/EIA 568-B (Cabling), TIA/EIA-569-A (Pathways and
Spaces) and TIA/EIA-607-A (Electrical Wiring, relevant as it pertains to
Earthing etc).
Even for short runs, If I need to run between buildings externally I won't
even look at copper.
Mark.
>
> I have a bunch of cat5 buried about 1 ft below the surface connecting
> multiple
> buildings on a campus (short runs) and lightning strikes nearby have
> caused
> surges along one or more of the cables and burnt out switch ports. I would
> like to protect the switch ports -- there seem to be lots of products on
> the
> market.
>
> Anyone have recommendations (tested/practical is best :-)?
>
> The APC Protectnet PNET1 and PRM24 seem quite nice and not too expensive
> --
> if they work....pros? cons?
>Adi,
Is there a reason that your between-building runs aren't being done with
Fibre?
It being non-conductive is one immediate advantage....
I would agree with Mark. Even buried copper can make an
excellent guide for lightning to come right into your equipment, and it can only be
isolated so much. (Remember, the electrical potential of the ground can vary over
a cable run, and will vary if there are elevation changes.) Fiber is the way to go.
Regards
Marshall Eubanks
R.P. Aditya wrote:
I have a bunch of cat5 buried about 1 ft below the surface connecting multiple
buildings on a campus (short runs) and lightning strikes nearby have caused
surges along one or more of the cables and burnt out switch ports. I would
like to protect the switch ports -- there seem to be lots of products on the
market.Anyone have recommendations (tested/practical is best :-)?
The APC Protectnet PNET1 and PRM24 seem quite nice and not too expensive --
if they work....pros? cons?Thanks,
Adi
I'll go with the fiber recommendation but that's not what you asked 
We use quite a few of the Motorola 300SS surge suppressors. They are
made for use with Motorola's fixed wireless Internet platform and go on
the Ethernet cable before it enters the building.
They do a good job of protecting the ports on near misses. Direct
strikes and they are toast along with anything attached to them - but
that's just the way it goes
First bond the cable shield to earth at the entry point in both buildings.
Second use a Tripplite DNET-1 at both buildings. make sure you have a single
point ground terminal that everything it bonded to and then that is grounded.
I am in the chicago area, and have towers and locations that have ethernet
cables running up to radios. We use this meathod, and don't have problems.
Worst we had after last night's T-storm was a site with out power 
Thanks to everyone who replied on- and off-list.
The installation in question is in a condo development and was done by
licensed electricians and the residents were lead to believe that it
was code compliant. The cat5 cabling is double-sheathed with a
moisture barrier.
As you can well imagine, the residents are very cost-concious. My
preference is that fiber be run in conduits, however even running cat5
in grounded conduit is a big hassle as it will involve cutting across
pavement etc. (I fully appreciate the danger from potential difference
between buildings and copper being a good conducter etc., but I had to
ask a leading question in order to document the problem such that
sufficient notice would be paid by the residents -- I believe I have
that now).
The short-term solution seems to be using the APC PNET1s/Tripplite
DNET1/etc. in each unit and tying them to the water main as an
inexpensive, immediate step while funds are allocated for conduit,
labor etc..
Thanks,
Adi