Sheilded Cat-5E Ground Loop - Myth or Reality?

Wed Apr 10 20:37:59 UTC 2002

> From: "Barton F Bruce" <barton at gnaps.com>
> Date: Wed, 10 Apr 2002 16:14:01 -0400
> Sender: owner-nanog at merit.edu
> 
> 
> > None of his is specific to Cat-5e installations but is common to ALL
> > electrical installations.
> 
> This does NOT apply to telco cables run outside, often run on the same poles
> parallel to power wires for miles, grounded at many points in a MGN (Multi
> Grounded Neutral) environment where, like it or not, the earth carries
> considerable current.
> 
> Opening a shield ground in this environment is bad.

Shielded/screened TP on utility poles? This is an insane thing to
do. It violates more rules than I want to even start to think about!
Telco wires are always connected to lightning arrestors at the
termination of the long run. (This is NOT always the same as the
demarc!) MGN is MANDITORY. This is not a do-it-yourself project.

Similarly, you should not do this between buildings either! (It would
probably not be a problem running the the garage, but if the next
building is on a different transformer...You could easily melt the
wires or burn something.

Or, to put it in simpler term, "Don't try this at home, kids!". It
could prove fatal. (Hint, power lines are always at the TOP of utility
poles and gravity works.)

R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at es.net			Phone: +1 510 486-8634