DC-GFP/2 protection [RE-wrenches]

[Bob Ellison, Alternative Energy Systems]

Grounding the negative cable is not required on systems under 50 volts as
most of us know.
My conversations with Mick Sagrillo and his articles on lightning protection
don't recommend grounding the negative. That way you don't give the
lightning surge a path to ground through the batteries.
I also put a lot of ground wire in a "net" around the base of the windmill
towers that I install or rebuild after a strike (not my install) and connect
it to the main ground system that way everything has the same ground
potential.
I too like to hook to the well casings if possible, it's hard to beat a 40'
ground rod.

Seems like the lightning "pulse" is more common damage than a direct strike.
Shielded cable seems to help on windmills with exposed cable.
I know of one 20 year old Bergey with the wire hanging in the tower that has
never had a lightning problem.
Come to think of it, there is no inverter, just a rectifier it is a 120 volt
DC system. Can't hurt an inverter that is not there!
Lightning control is almost a black art, and sometimes nothing helps.

Just my .02 worth, your opinion will vary.
Bob

RE. Ellison
Supplier of;
Alternative Energy Systems & Supplies
34642 Countryman Road
Theresa, NY. USA
                               13691-2076


-----Original Message-----
From: David Palumbo, Independent Power & Light [mailto:ipl at sover.net]
Sent: Thursday, August 22, 2002 9:43 PM
To: RE-wrenches at topica.com
Subject: RE: DC-GFP/2 protection [RE-wrenches]


Jeff,

Wow! What a timely message for me to see. I have always gone by the book and
bonded DC negative to ground at one point in the system and have experienced
no more than the occasional lightning issues.

However I have been recently considering a change to a floating DC system. A
tech at one of my distributors had my ear on this issue and he was convinced
that floating the DC negative would help with lightning protection. He also
said that there was some sort of movement to do away with the language in
the code that mandates the DC negative bond to ground.

Dave Palumbo
IP&L


-----Original Message-----
From: Jeff Yago [mailto:jryago at earthlink.net]
Sent: Thursday, August 22, 2002 9:12 PM
To: RE-wrenches at topica.com
Subject: RE: DC-GFP/2 protection [RE-wrenches]


We just returned from inspecting a brand new 4 month old system (that we did
not install!!) that had BOTH SW5548 Trace inverters "fried" by lightning.
This was a 4800 watt totally off grid system.  The AC side of the inverters
supply a standard 120/240 volt house panel that was grounded properly.  The
ground mounted array frame was grounded properly also.  However, the
negative of the DC side of the inverter, batteries, and charge controllers
were not grounded.

The lightning was "nearby" but was not a direct strike.  Since there was no
grid connection, the surge could not have entered the AC side.  I for one
like grounding the DC side and wish this installer had done so also.

Jeff Yago

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