Subject: Re: Grounding on more than 1 point dangerous?
From: Henry Spencer <henry@zoo.toronto.edu>
Date: Feb 21 1996
Newsgroups: comp.dcom.lans.ethernet

In article <4g9vv4$164_002@merry.bitmailer.com> saivex@bitmailer.net
(Daniel Donate Reuss) writes:

>I have seen in the FAQ (yes, I have read it :-) ) that grounding an Ethernet 
>network on more than 1 point can even be dangerous to people, but it doesn't 
>explain why. Can sb. tell me the reason? (Just curiosity)

There can be significant voltage differences between so-called "grounds"
at different points in a building.  (Anyone who runs copper Ethernet
cables *between* buildings should be shot.)  If your Ethernet cable is
connected to one of them, and you're about to plug in a connection that
will ground it to another one, you are completing a circuit that may have
rather a lot of current flowing in it.  That's inherently dangerous. 
-- 
Space will not be opened by always                 |       Henry Spencer
leaving it to another generation.   --Bill Gaubatz |   henry@zoo.toronto.edu