[RE-wrenches] Fwd: Grounding on a glacier??

[Matt Tritt]

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.

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.

Matt T

Darryl Thayer wrote:

>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 <toddcory at finestplanet.com> wrote:
>
>  
>
>>From: Todd Cory <toddcory at finestplanet.com>
>>Subject: Re: [RE-wrenches] Fwd: Grounding on a glacier??
>>To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
>>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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