DC-GFP/2 protection [RE-wrenches]

[Steve Bell, Sunwize Technologies]

Hi Joel, et al,

I live out on the prairie of Illinois and we get some real wrath-of-god
thunderstorms. I have an old long-case Jacobs on a 115' tower (tallest
structure within several miles)as well as both a roof-mounted PV array and a
second array on a tracker. I float my DC wiring completely; it is totally
ungrounded except for being connected to Delta LA302DC lightning arrestors
installed at the base of the tower and the combiner boxes of each array. My
system operates at 48 VDC with dual SW (not stacked) and I sell my excess
back to the grid.

I have very good grounding on the tower (ground rods on all four guy anchors
and the base of the tower) and on frames and racks of the PV arrays. I also
use Delta LA302R arrestors on both the AC input from the grid and the AC at
the subpanel (AC output of the SW inverters).

We have experienced some severe electrical storms that have caused
significant damage to my neighbors electrical equipment, but I have not had
any damage to my equipment. The only lightning damage that I every
experienced occurred when my system was new and the Delta arrestors were not
yet installed (they were on backorder). A nearby lightning strike caused a
huge surge on the utility AC line that blew out the microprocessors of the
SW. That was about 5 years ago. Since then, no problems.

I have yet to hear a clear technical reason (not just because its code) for
grounding the DC conductors. I firmly believe that a floating DC system is
both safer and less prone to lightning damage. I do believe in very good and
solid chassis/equipment grounds.

So, I would request that the Code Review committee consider removing from
the 2005 NEC, the requirement to ground DC systems. Or prove with solid
technical reasons why grounding the DC wiring is requirement for safety. If
DC systems were allowed to be floating, we could also do away with all the
silliness and cost and hassle of PVGFP.

Okay, go ahead and blast me.

Sincerely,
Steve Bell
Stelle, IL
sebpv at stelle.net

----- Original Message -----
From: "Joel Davidson" <joeldavidson at earthlink.net>
To: <RE-wrenches at topica.com>
Sent: Thursday, August 22, 2002 10:53 PM
Subject: Re: DC-GFP/2 protection [RE-wrenches]


> Jacobs use to float the DC negative on his wind machines to prevent
lightning
> damage. He grounded the tower with a ring of copper wire 10 feet out from
the
> tower base buried about 18 inches to form a cone of protection. I resisted
> (pun?) grounding the DC negative for years, but finally gave up. However,
my
> systems are almost all in regions with low lightning danger. What say you
guys
> in lightning territory?
>

- - - -
To send a message: RE-wrenches at topica.com

Archive of previous messages: http://www.topica.com/lists/RE-wrenches/

List rules & etiquette: http://www.mrsharkey.com/wrenches/etiquete.htm

Check out participant bios: www.mrsharkey.com/wrenches/index.html

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com

==^================================================================
This email was sent to: michael.welch at homepower.com

EASY UNSUBSCRIBE click here: http://topica.com/u/?bz8Qcs.bz9JC9
Or send an email to: RE-wrenches-unsubscribe at topica.com

T O P I C A -- Register now to manage your mail!
http://www.topica.com/partner/tag02/register
==^================================================================