Lightning Revisited [RE-wrenches]

[Bill Brooks]

Joe,

What about employing the grounding of separate structures provision in NEC
250-32 (2002 code)? If there is a grounded conductor, then that conductor
should be grounded at the tower (or PV Array for PV) and at the service
entrance with no ground wire between them and no metalic conduit. All
ungrounded conductors must have surge protection (Phasor, Delta, voodoo).
The main issue is that you cannot touch the tower or module frames while
touch something connected to the house. The inverter, however, is working
with conductors that are all referenced to the same grounding system.

Bill.


-----Original Message-----
From: Joe Schwartz, Home Power [mailto:joe.schwartz at homepower.com]
Sent: Thursday, April 11, 2002 4:29 PM
To: RE-wrenches at topica.com
Subject: RE: Lightning Revisited [RE-wrenches]


Hey Jeff,

One place I flat out refuse to follow the NEC is bonding wind
generator equipment grounds to the main system equipment ground. Take
a 100' metal pole (talk about a lightning rod) and connect it to the
same ground system servicing inverters and charge controllers? Don't
think so!

Joe



>I think that I was misunderstood - this grounding issue is important. I
only
>meant for the lightning rod and its dedicated ground grid to be isolated
>from the system ground. By no means, do I suggest that the system is
>ungrounded or that electrical systems on the same service have separate
>grounds. I'm simply saying that putting up a path of least resistance - the
>lightning rod and ground grid, you have a better chance of the lightning
>finding it before the equipment. If these two earth grounds (lightning and
>PV system) were to be bonded you would increase the chance of current
>finding its way to equipment.
>
>Am I incorrect in saying that the lightning rod and its dedicated ground
>grid does not have to be bonded to the system ground?? If it must all be
>bonded, then the lightning rod would likely only make matters worse,
>however, this would be news to me (not the first time!).
>
>-jeff
>
>>	From the Solar, Wind & Hydro Powered office of:
>>	Jeff Oldham
>>	Gaiam- Real Goods & Jade Mountain
>>	Design & Consulting Group
>>	11755 Mid. Mtn. Rd.
>>	Potter Valley, CA 95469  USA
>>
>>	Ph: 303.222.3814
>>	Fax: 707.743.1820
>>
>>	www.solardevelopment.com
>>
>>	"When you turn to face the Sun all shadows fall behind you"
>>	- Old African Proverb
>>
>
>
>-----Original Message-----
>From: Bill Brooks [mailto:billbrooks7 at earthlink.net]
>Sent: Thursday, April 11, 2002 11:50 AM
>To: RE-wrenches at topica.com
>Subject: RE: Lightning Revisited [RE-wrenches]
>
>
>Lightning rods only have a 45 degree downward cone of protection. Proper
>grounding, as previously mentioned, is the best method. The idea of
>grounding the frames separately from the system ground is not a good idea.
>Everybody has their fetishes related to grounding, but the grounding folks
>suggest using a good ground and tieing all the ground rods together. Not
>tieing them together presents a very real possibility of raising the
voltage
>in the current carrying conductors while the frames stay closer to ground
>potential--not good. If there is any rise in voltage, you want everything
to
>rise together. That way the transistors in the inverter don't get smoked.
>
>Bill.
>
>
>-----Original Message-----
>From: jeff.oldham at realgoods.com [mailto:jeff.oldham at realgoods.com]
>Sent: Thursday, April 11, 2002 11:40 AM
>To: RE-wrenches at topica.com
>Subject: RE: Lightning Revisited [RE-wrenches]
>
>
>I like the PolyPhaser idea and would go with one. I would also install a
>lightning rod higher than anything else in the area bonded to a good ground
>grid of 4 ground rods and NOT bonded to the system ground. With luck (and
>that's all you get with the wrath of lightning)the strikes will find the
rod
>tastier.
>
>Good luck!
>-jeff
>
>>	From the Solar, Wind & Hydro Powered office of:
>>	Jeff Oldham
>>	Gaiam- Real Goods & Jade Mountain
>>	Design & Consulting Group
>>	11755 Mid. Mtn. Rd.
>>	Potter Valley, CA 95469  USA
>>
>>	Ph: 303.222.3814
>>	Fax: 707.743.1820
>>
>>	www.solardevelopment.com
>>
>>	"When you turn to face the Sun all shadows fall behind you"
>>	- Old African Proverb
>>
>
>
>-----Original Message-----
>From: Jeffrey Wolfe, Global Resources [mailto:global at sover.net]
>Sent: Wednesday, April 10, 2002 6:59 PM
>To: 'RE-wrenches at topica.com'
>Subject: RE: Lightning Revisited [RE-wrenches]
>
>
>The local lightning guru around here got somewhat involved in adding
>lightning protection to a major grid-tie solar project here, and before he
>decided it was too complex to tangle into, he did recommend an incoming
>service surge suppressor by PolyPhaser. You run the entire service through
>it, so it's a large unit. For a 200A service, you're looking at $1500 or
>so, plus installation. We don't have enough time on it to say that it's
>going to stop the flashes, but the lightning guy was pretty convinced that
>the service entrance was by far the most vulnerable, given that the rest of
>the system has plenty of the Delta cans on it.
>
>Jeff
>Jeffery D. Wolfe, P.E.
>Global Resource Options, LLP
>A Woman-Owned Limited Liability Partnership
>4 Kibling Hill Road
>P.O. Box 161
>Strafford, Vermont 05072
>800-374-4494 Toll Free
>802-765-4632 Phone
>802-765-9983 Fax
>global at sover.net
>http://www.GlobalResourceOptions.com
>
>Nextek Certified Distributor
>SolarWall Certified Distributor
>Trace Certified Dealer - Charter Member
>Bergey Windpower Certified Dealer
>
>
>On Wednesday, April 10, 2002 10:17 AM, Holt Kelly [SMTP:hkelly6 at msn.com]
>wrote:
>>  Hello all,
>>  I am designing a 2kw grid-tie w/battery backup in an area that seems to
>>  be prone to lightning strikes (lost power from strike last week for the
>>  third or fourth time this year). The client wants to be sure the system
>>  is well protected. I have some ideas of over engineering the surge
>>  protection but was wondering if ya'll had any ideas. Thanks in advance
>>  "We do not inherit the earth from our parents. We borrow it from our
>>  children."
>>  Chief Seattle
>>
>>  Holt E. Kelly
>>  Holtek Fireplace & Solar Products
>>  Waco, TX.
>>  hkelly6 at msn.com
>>
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>
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--

-------------

Joe Schwartz - Tech Editor
Home Power Magazine
joe.schwartz at homepower.com
www.homepower.com

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