Lightning Revisited [RE-wrenches]

Joe Schwartz, Home Power joe.schwartz at homepower.com
Thu Apr 11 16:29:24 PDT 2002


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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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