Steve Wolfe wrote:
>>>With patch cords, which are typically short, it would appear that STP
>>>would be insignificantly different that UTP.
>>
>>Plus don't you have to earth them [STP] at one end?
>
>
> And *only* one end. Grounding (Earthing) at both ends creates a path for
> current to flow to ground OTHER than the mains wiring, and if there are a
> few amps (or more) going to ground, you do *not* want it going through your
> shielding ("Hey! Why did the network just die?"). You also don't
> necessarily need the hum from having the ground loop, either.
>
> steve
>
>

Just an anecdote about grounding. A couple of years ago, working on a
seismic crew in the desert, where offices are setup in trailers for a
few weeks, I happened to find out that the gounding of some trailer was
badly setup. We had coaxial cable on the network at the time. Working
on a pc, connecting a (metallic) BNC to a card, I happen to notice a
tiny spark. By curiosity, I redisconnected, took a multimeter and
checked. The reading was 90 volts... But nobody was complaining about
the network. (!)

Gaetan