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I have no question as to the advantage of high voltage grounding - it's
the LVDC side I'm trying to figure out. I think it's pretty interesting
that, so far, no one has come up with an actual, technically proved
reason why the battery conductors need to have a ground. It is about as
likely to have a 13 kv conductor fall on a battery cable (interesting
thought, though), or to have lightning zap one as it is to be a victim
of union bothering and wire company greed.<br>
<br>
Having begun my foray into the wonderful world of E-lec-tricitee
building electrical systems in boats (like 45 years ago) that included
DC, AC and radio circuits, I have no problem with floating grounds. Ha
ha. Seriously; I can see no reason what so ever why we are required to
ground any part of the low voltage side in a battery based system and,
as far as I can see, all it does is create a potentially dangerous
situation where none would otherwise exist. I'm not talking about fire
risk, since I doubt that that is the reason.<br>
<br>
Matt T<br>
<br>
Darryl Thayer wrote:
<blockquote cite="mid569572.99831.qm@web51909.mail.re2.yahoo.com"
type="cite">
<pre wrap="">The reason for grounding to limit the hazards associated with fault conditions. If a utility source is unintensionally connected to high voltage the pair of wires can be at elevated voltage. example would be if a 13,000 volt line falls onto a 120 volt line, the 120 volt line can be raised to 13,000 volts, and the victium would be fried. So we ground such that the 120 line can not get higher than 120 volts above ground.
The reference to ground is because we are referenced to ground as we stand bare foot and
Darryl
--- On Fri, 7/24/09, Todd Cory <a class="moz-txt-link-rfc2396E" href="mailto:toddcory@finestplanet.com"><toddcory@finestplanet.com></a> wrote:
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<blockquote type="cite">
<pre wrap="">From: Todd Cory <a class="moz-txt-link-rfc2396E" href="mailto:toddcory@finestplanet.com"><toddcory@finestplanet.com></a>
Subject: Re: [RE-wrenches] Fwd: Grounding on a glacier??
To: "RE-wrenches" <a class="moz-txt-link-rfc2396E" href="mailto:re-wrenches@lists.re-wrenches.org"><re-wrenches@lists.re-wrenches.org></a>
Date: Friday, July 24, 2009, 10:50 AM
I have heard that
this
requirement (to bond negative to ground) as well as bonding
one of the
AC conductors to ground (neutral wire) was pushed through
by wire
manufactures and unions. The wire manus sell more of their
product and
the electricians get more labor in installing them. I also
agree that
grounding any live conductor actually makes the system less
safe.
When I have traveled over seas, I always try to open the
main panel to
see how things are laid out. They never associate one of
their power
conductors (usually 240 v) to ground.
Todd
Matt Tritt wrote:
As long as we're already on the subject, BESIDE the NEC
requiring it,
why is it that we have to bond the ungrounded conductor on
the battery
side of a DC system??? I believe that we are the only
country in the
world that has this requirement. As long as all the system
cabinets,
mounting plates, housings and etc are grounded, what is
gained by
including a battery conductor? I'm not talking about HV
inputs from an
array, just the battery busses.
I have been asking this question since forever, and the
only
explanation seems to be the recital of the Code. Obvious
problems can
occur when there is a + grounded piece of equipment in the
mix, since -
well, it's obvious.
Matt T
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