On Sat, 01 Oct 2011 15:54:57 -0400, wrote:

On Sat, 01 Oct 2011 12:00:27 -0500, "
wrote:

Says who? A Farraday cage is a Farraday cage
whether it's grounded or not.

My experience has been an ungrounded sheild just becomes an antennaa

It can, if the equipment is junk. It can also be a rather nasty current path
if the "local grounds" aren't.

That is why you only ground one end. You are not providing a current
path, just a drain for whatever transients the shield would catch.

Prezactly.

In the case of data cabling, STP is really pretty rare and they do
very well running gigabit ethernet over UTP. Most of it is just that
they are a lot better at noise rejection in the adapter itself. The
idea that anything generated in a 20a Romex running next to a CAT-5 is
going to spike an ethernet adapter is ludicrous.

STP is used if the hardware is dirty. Over the last few decades, LAN hardware
has been cleaned up to where it's not needed. STP helps the "antenna
problem", above, but it shouldn't be needed anywhere.

When I was in the cabling biz at IBM I set un an experiment with CAT-3
trying to break an Ethermet or a Token Ring LAN doing every urban
legend bad thing anyone could think of (loops of cable over
fluorescent ballasts, running next to 480v 1600a feeders, taped to the
raceway, telephone in the same cable, exceeding the 300' rule, etc)
Basically I couldn't break it.

10-baseT, 4/16MB T/R only?

What did have an effect, kinks in the cable, sloppy terminations and
driving a staple through the cable. Those were handy for the second
phase of the experiment, finding bugs doing TDR with a scope.