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From: dsi@unccvax.UUCP (DataSpan R+D)
Newsgroups: sci.electronics
Subject: Re: Neutral-Ground Shorts
Message-ID: <753@unccvax.UUCP>
Date: Mon, 22-Jun-87 12:57:00 EDT
Article-I.D.: unccvax.753
Posted: Mon Jun 22 12:57:00 1987
Date-Received: Tue, 23-Jun-87 04:39:03 EDT
References: <820@sdcc12.ucsd.EDU> <583@inuxh.UUCP> <467@rlvd.UUCP> <258@uvicctr.UUCP>
Organization: Univ. of NC at Charlotte, Charlotte, NC
Lines: 29

In article <258@uvicctr.UUCP>, collinge@uvicctr.UUCP (Doug Collinge) writes:

> What I have wanted to know for years is,  why is residential service
> referred to ground at all?  I understand why they balance and ground 
> high-voltage transmission lines.  It seems to me that, if the transformer
> was used to isolate the residential service from ground everyone would

     I for one would much prefer the service coming into my home to be
referenced to earth ground.  As an engineer who (occasionally) builds
broadcasting stations, I can assure you that the effects of lightning
strikes are swift and dramatic.  If the distribution system in the home
were left in an essentially floating, balanced line condition, the danger
of electrocution due to leakage from L1-L2 to a cold water pipe (say, the
poorly designed toaster in the kitchen) would be minimized.  The danger 
from fire due to extremely high voltage transients would not be minimized.
It is much easier to insulate 240 VAC than a few million volts of very
high current pulses from a dwelling and its occupants.

     Pole transformers (which actually have the secondary windings isolated, 
but the center tap is grounded to the case *at the pole*) would probably
get internal shorts anyway just as soon as a service drop was hit, which
would negate any of the advantages of balanced line operation. Increasing
the insulation required for this service would drop transformer efficiency.

     The best solution are ground fault interrupters, in conjunction wiht
the present system in use.

David Anthony
DataSpan, Inc