Grounding on granite island [RE-wrenches]

Sat Apr 7 04:44:28 PDT 2007

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Several years ago we designed and furnished an off grid 2 kw system for an 
extremely remote research facility in Gabon, Africa. It is located on a huge 
slab of rock in the middle of the rain forest ,with tall trees all around, 
on the equator and miles from the nearest dirt road. Most supplies were 
delivered by helicopter. All the buildings were built on piers on the rock, 
so a Ufer was not an option. Shallow wet ground was several hundred feet 
away at the edge of the rock and near a shallow river. So we supplied a 
large sheet of recycled heavy gauge copper roofing with copper grounding 
cable soldered to it, and several clamps to attach a #4 copper ground wire 
from the array and inverters. Surge protectors were of course built in to 
the Outback power panel . 302's I think, probably should have used the 
really good one's from Polyphaser, I think. Instructions were to bury this 
copper plate in as wet a place ,and as deep, as possible. They have quite a 
few lightning storms. So far they are quite pleased with the system, which 
powers the office and kitchen, including refrigeration. IE; It hasn't been 
zapped yet !

My questions to the assembled wisdom of this group are;
-- was this the best solution and/or could it be improved?
--During the dry season, should they be sure to keep wet the area where it 
is buried ?
--Should a lightning protection system, like those used on houses, be 
considered? Or is the marginal grounding point the main issue?
--What is the best way to test the effectiveness of the existing ground 
system, including the path from PV panel to mounting system [ alum. rack on 
wooden support     structure] to ground wire across rock?
        This wire by the way, was supposed to have been encased in latex 
modified cement mortar to fasten it to the rock so the people and elephants 
wondering thru         camp wouldn't dislodge it !
--What else should be considered?

Everything has to be shipped by container from NY. We have some smaller 
systems leaving in several weeks, and if improvements are to be made, this 
would be the time.

Thank you in advance for your thoughts, and time.

Ken Schaal
CommonWealthSolar,LLC

----- Original Message ----- 
From: "Phil Undercuffler" <p.undercuffler at conergy.us>
To: <RE-wrenches at topica.com>
Sent: Friday, April 06, 2007 10:59 PM
Subject: RE: Grounding on granite island [RE-wrenches]

>
> Are they pouring concrete footers?
>
> Establish a Ufer ground by tying to the rebar in the foundation. Here in
> the dry Southwest, it's the preferred grounding method in the area --
> fast, easy, effective and very nearly free.
>
> Have the concrete sub bend up a piece of the footing rebar, and leave
> 9-10" exposed out of the slab in the area of the power system.  Connect
> to it with a two piece grounding "saddle" clamp, which makes a bronze to
> steel connection, and keeps the copper conductor isolated from the
> steel.
>
> Of course, if they aren't pouring a concrete foundation this wouldn't
> help.
>
>
> ------------------------------------------------------------------
>
> Phil Undercuffler
> Technical Services Manager
> Conergy, Inc.
> 1730 Camino Carlos Rey Suite 103
> Santa Fe NM 87507 USA
> Office | 505.473.3800 x4841
> Fax | 505.473.3830
> www.conergy.us
>
> ------------------------------------------------------------------
>
> -----Original Message-----
> From: Michael Welch [mailto:michael.welch at homepower.com]
> Sent: Friday, April 06, 2007 10:57 AM
> To: RE-wrenches at topica.com
> Subject: Grounding on granite island [RE-wrenches]
>
>
> Hi gang I an email awhile back about a grounding question, and a
> follow-up phone call today.
>
> This fellow is building a PV/wind/generator system for small cottages on
> a solid granite rock out on Lake Huron. His earth grounding plan is to
> haul a big steel plate out onto the ice (will need to do this pretty
> soon) and let it sink to the lake floor as a way of grounding the
> system.
>
> Or he may be able to submerge a plate in his graywater pool.
>
> There is no more than 6 inches of earth above the granite on the island.
> He does not have access to the kind of equipment needed to drill deep
> holes in the granite, but he can drill 6 or so inches deep.
>
> His RE dealer has been no help because of the unusual nature of the
> problem, and he has not been able to get help from local electrical
> engineers and electricians for the same reason.
>
> He wants to know if he is doing this correctly, and what size plates to
> use, how many, and anything else you can think of.
>
> You can either respond here if you think it will be of interest to the
> list, or if you need more info and want to carry out an email
> conversation with him, let me know off list and I will get you his email
> address.
>
> Thanks in advance for your help.
>
>
> ------------------------
> Michael Welch
> Sr. Editor
>     Home Power magazine
>     www.homepower.com
>
>
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