Grounding on granite island [RE-wrenches]
Darryl Thayer
daryl_solar at yahoo.com
Sun Apr 8 09:28:02 PDT 2007
Hi everyone
It appears that two methods have been suggested, a
ground plane and getting to a real ground.
As I understand it, the ground plane system is ok as
long as all parts of the system are above or within
influence of the ground plane. When a lightening
strike occurs the whole system is elevated and no
difference of potential currents occur. This works
for smaller foot print systems, such as towers and met
stations.
When the system gets spread out the area of the ground
plane becomes more difficult to maintain. Then
grounding all parts of the system to a real ground is
better. I would prefer to try a real ground, such as
deep holes or a copper wire to a copper plate in the
water. As long as the Iron plate does not corrode and
the connection stays somewhat solid, the steel plate
should work.
NOw for the real dump part. I would run from the
source system Hots, Neutral and Ground wire. Do not
ground the neutral at any more than one point. But
ground all other things, roofs, metal parts to the
ground wire. The tower is considered a
ground/lightening protection for 45 degree cone from
the top of the wind tower, out side of this radius
objects are subject there own strikes.
Darryl
--- Dan Brown <Cvsolar2 at aol.com> wrote:
> hi guys;
> dan here. i was involved with a project on
> top of killington here in
> central Vermont a few years ago. the folks
> installing the transmitter goodies
> had to excavate like a 50'x50' hole a few ft deep.
> then they laid out a copper
> mesh, then trucked in bags of stuff to bury the mesh
> in (like 200 bags). then
> buried the whole mess. don't recall the name of the
> stuff. it was green and
> heavy -- and pricey as i recall. might have been
> called a counterpoise (sp?)
> system. good luck. db
>
> Dan Brown
> Foxfire Energy
> Professional Renewable Energy Systems
> Service, and Installation
> (802)-483-2564
> www.Foxfire-Energy.com
--- Ray Walters <walters at taosnet.com> wrote:
> Oh we had ground rods in as far as we could get
> them, cut and set the
> left over piece its length from the original blah,
> blah, blah.
> Lightning usually comes before the rain, and dry
> soil over rock just
> has no conductivity. I'm shopping for a ground
> impedance tester to
> try and remove the guess work, but at $1500 they're
> hard to recoup
> the investment. I guess I could charge like the
> hospital, and each
> gadget that gets pulled out of the bag o' tricks
> gets billed out.....
> I think the main thing in lightning protection is
> that we do our
> best, but there are no guarantees. Don't forget
> whose idea it was to
> build on a hunk of granite in the first place.
> I wouldn't lose sleep over it.
>
> Ray
>
>
> On Apr 7, 2007, at 2:50 PM, Ken Schaal wrote:
> > Gee Ray, that really ruins my afternoon-----
> > Bet it ruined yours more !
> > What was at the working end of your ground wire?
> > Thanks
> > Ken
> > ----- Original Message ----- From: "Ray Walters"
> <walters at taosnet.com>
> > To: <RE-wrenches at topica.com>
> > Sent: Saturday, April 07, 2007 1:52 PM
> > Subject: Re: Grounding on granite island
> [RE-wrenches]
> >
> >> 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.
>
=== message truncated ===
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