Grounding on granite island [RE-wrenches]
Ray Walters
walters at taosnet.com
Sat Apr 7 10:52:27 PDT 2007
<x-flowed>
We did an installation on a rocky mountain top in West Texas several
years ago. Same thing: solid rock 6" below the surface. This system
featured a 50 ft tall wind generator as well. We dutifully tied all
the grounds together, ran copper outside of the conduit to enhance
the conductivity to ground, put in polyphasor lightning protection, etc.
A lightning strike apparently to the wind generator sent a surge
through the grounding system that took out 2 SW4024s, the charge
controller, the Omnimeter, and the Kohler control for the generator.
After that, we ran a 1/2" steel cable ( that's what they had
already) and ran it from our existing ground system a 1/2 mile to a
steel cased well in the valley below. Seems to have done the trick,
as we haven't had any trouble since. That is a lot of cable, but that
was a lot of equipment taken out too.
Ray Walters
On Apr 7, 2007, at 5:44 AM, Ken Schaal wrote:
>
> 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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>
>
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> wrenches/read
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>
R. Walters
Solarray.com
NABCEP # 04170442
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