Date: Wed, 2 Feb 2005 09:52:46 -0500


Subject: RE: The physics of grounding


20 years ago, as an Engineering Tech, I oversaw the installation of a high tech
grounding system for a large electronic testing facility. The requirement was
something like conducting 10 amperes at 1V from one grounding rod to another
placed a known distance away (I forget d but, <100ft.) We were unable to meet
the req't even after driving 30ft. rods because the local area was a specific
clay soil. I don't know of any situation where charge build up was significant
beyond electronic sensing in very low signal processing.

-------------Quoting "Papp, James J " :

> It is not the electric fields, grounding works because the earth is so large,
> and essentially neutrally charged, and a good enough conductor, that anything
> electrically connected to it can treat it as a 0 V constant. Any conceivable
> number of electrons pumped in or out of the ground is so vanishingly small
> compared to the electron count of the earth as a whole that one can safely
> ignore the voltage change induced.
> I'm sure there are some exceptions - lighting or other high amperage sources
> that can momentarily change the base voltage in a local area, but the soil is
> conductive enough that these disruptions are quickly neutralized.
> Just out of curiosity - has anyone heard of soils or locations that have poor
> enough conductivity that charge *can* build up? I know that right before
> lightning strikes, there is a Van der Waal-like effect where the ground,
> trees, buildings and so on build up a charge in response to the charged
> clouds overhead, but I'm thinking more along the lines of electrophorus.
> Thanks
> James Papp
> College of Lake County
> -----Original Message-----
> From: Matt Lowry [mailto:MLowry@D115.ORG]
> Sent: Tuesday, February 01, 2005 3:32 PM
> To:
> Subject: The physics of grounding
> Howdy Tappers,
> Got a question... why is it that grounding works? Doesn't it have
> something to do with the fact that the Earth just naturally has an
> electric field? I just need to read up a little on this...
> Cheers,
> Matt Lowry
> Lake Forest HS
> Lake Forest, IL

From Wed Feb 2 09:50:46 2005