Electrolysis Damage Story [RE-wrenches]

Fri May 6 11:04:11 PDT 2005

Your free subscription is supported by today's sponsor:
-------------------------------------------------------------------
Want a laptop? Get an Apple iBook for free! 
http://click.topica.com/caadtaHbz8Qcsbz9JC9a/Amazing Computer 
-------------------------------------------------------------------

Hi Darryl,

I'm the one that actually discovered the damage. I measured the voltage
to ground, literally. The ground was damp and has been all winter from
rain - so the moisture is penetrating deep into the soil. I got a very
solid reading. I thought to do it after having very strange behavior
apear with a new tracker controller that I was installing. The crazy
behavior it was exhibiting made me think there was a grounding issue -
like the chassis of the controller was not at ground potential. So I
stuck my black lead in the ground, and viola, 28VDC solid and
repeatable, everywhere on the tracker and the pole. It was fun, try it
sometime. Allan didn't mention that before inspecting the pole I looked
at the grounding electrode conductor to see why this potential was not
dissipating. It was eaten away where it entered the ground all the way
to the electrode - stray current electrolysis, definitely not rust. So
then I wondered why the pole itself was not grounding the array. That's
when I found the pole damage. Both the pole and the GEC have been
passing current to some degree the whole time, but the wet ground this
winter probably reduced resistance to ground considerably and
accelerated the electrolysis. The wet ground certainly accelerated any
rusting of the steel pole as well. Simple oxidation is certainly
involved with the steel, but I was under the impression that once there
is a rust layer blocking oxygen from contacting the steel, the process
halts. I could be wrong about that. Anybody an expert on rusting?

I'm still not sure if there is a grounding electrode at the house. There
was a grounding conductor running that direction. The house was locked
and the owners were gone. If there is, it is certainly compromised, or
the charge would have dissipated through that path. The same thing might
have happened to that GEC, if it exists, since it certainly would have
passed part of the fault current. I reconnected to the old ground rod
and drove a new one to be safe. 

Mark Drummond
Positive Energy Inc.
(505) 424-1112
mark at positiveenergysolar.com
Enjoy the sun!

-----Original Message-----
From: Darryl Thayer [mailto:daryl_solar at yahoo.com] 
Sent: Friday, May 06, 2005 4:59 AM
To: RE-wrenches at topica.com
Subject: Re: Electrolysis Damage Story [RE-wrenches]

Your free subscription is supported by today's sponsor:
-------------------------------------------------------------------
Sign up today for a No Annual Fee DiscoverR Platinum Card and get. 0%
Intro APR on Purchases & Balance Transfers for 8 Months, Up to 
2% Cashback BonusR reward on your purchases & 100% fraud 
protection. http://click.topica.com/caadtrVbz8Qcsch202ka/DiscoverCard
-------------------------------------------------------------------

Hello
I reject the basic premise. I have seen similar
events, many times, both on electrical posts and non
electrical posts.  I have seen many mailbox support
posts rust off at the bottom.  If water can enter the
post the rusting is faster.  If the soil is acidic the corrosion is much
faster.  Further I am puzzled as to how voltage was determined at the
pole. (what was it measured from?) I think if you drive a copper ground
rod and a Galvanized pole you have a electrolysis potential.  If it
rains, the water splashes against the pole and stays moist at the bottom
longer than anywhere else.  The moisture splashed water and soil are the
sources of the corrosion.  Some inspectors in my area would require the
concrete extend above the ground and taper away from the pole.  

I always ground the array frame, and the pole, and
include a ground conductor back to the ground at the
house.  A GFDI is not required in this case, and I
would have 'if the inverter allowed' grounded one of
the PV conductors at the house (at a single point). By
using a ground on one of the PV conductors the loss of performance
should have been easily detectable.

If you had a high voltage inverter it would have had a
GFDI installed.   
Thanks Darryl
Others please respond if you have rusting at the
bottom of the pole and how to control.

--- Allan Sindelar <allan at positiveenergysolar.com>
wrote:
> Wrenches,
> A simple mistake can have major consequences.
> 
> In 1997, in my first year of business, I designed
> and sold a SW4024-based
> grid-tied system for a new home. As I wasn't
> licensed at the time, another
> local electrical contractor with a history of doing
> solar installations was
> separately contracted to pull the permit and do the installation. Upon
> completion, I corrected a few things I didn't like
> (battery cables connected
> at one end of the bank, rather than diagonally, for
> example) and have
> supported the system and the customer in the years
> since. This is a good
> customer.
> 
> The system has worked well, with only the Wattsun
> tracker and the E-Meter
> requiring repair or replacement. The client called
> recently about tracker
> malfunction, and today Mark (partner) went to the
> site to service it. What
> he found was battery voltage at the tracker ground,
> which he determined was
> from a ground fault at the array. The galvanic
> action caused by the fault
> had rusted the 8-year-old 6" Sch 40 steel pole to
> the point that he could
> poke a screwdriver through the pole at the base, and
> was concerned about the
> whole thing toppling over any minute.
> 
> The cause of the ground fault was the use of two
> 1/2" Romex clamps for
> strain relief where the USE-2 array input conductors
> entered a steel 3R
> combiner box on the pole. Each of the two clamps
> held four #10 USE-2
> conductors and one bare #8 or #10 grounding
> electrode conductor. One of the
> clamps had shorted one of the PV+ conductors to
> ground. I am guessing that
> it had been like this for a long time, maybe since installation, and I

> had never detected the fault during routine service
> calls. An array GFDI wasn't
> installed or required (and I'm not sure anyone even
> made one at that time).
> 
> The customer is looking at repair options for the
> pole, including outriggers
> with driven steel posts and welded braces, and a
> poured concrete cap over
> the base of the pole. We will head out soon to
> disassemble the array, to
> reduce wind sail and the chance that it will come
> down, and to buy some time
>  for a good repair to be devised. We are also
> looking at setting a 5" steel
> pole inside the 6", with cement slurry between the
> two.
> 
> We haven't worked out a course of action yet. A
> couple of questions:
> 
> We use SO connectors for USE wire, and use Romex
> clamps for jacketed wire in
> indoor locations. Is the use of Romex clamps on USE
> wire in this application
> legal per NEC? What Code section addresses this?
> If issues of liability and responsibility come up
> (and they probably will
> not) who's liable? The contractor who installed the
> system and pulled the
> permit? The inspector who signed off on the job? Us?
> How would you serve the
> customer in this case? I supplied a one-year
> warranty on system design and
> component failures, and the installer gave the same
> against failures due to
> incorrect installation.
> 
> Has anyone ever repaired a rusted pole? Howdja doit,
> and did it work?
> 
> Thanks for any good advice. I'll share your
> responses with the client.
> 
> Allan at Positive Energy
> 

Discover Yahoo! 
Get on-the-go sports scores, stock quotes, news and more. Check it out! 
http://discover.yahoo.com/mobile.html

Your free subscription is supported by today's sponsor:
-------------------------------------------------------------------
Get both the MiFi XM Satellite Radio and an Apple iPod for Free! 
http://click.topica.com/caadtaJbz8Qcsch202kf/ProductTestPanel 
-------------------------------------------------------------------

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

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

List rules & etiquette: www.mrsharkey.com/wrenches/etiquette.php

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

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com

Your free subscription is supported by today's sponsor:
-------------------------------------------------------------------
Need a Laptop? Get a Sony Vaio Laptop Free!
http://click.topica.com/caadtaFbz8Qcsbz9JC9f/ProductTestPanel
-------------------------------------------------------------------

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

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

List rules & etiquette: www.mrsharkey.com/wrenches/etiquette.php

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

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.bWljaGFl
Or send an email to: RE-wrenches-unsubscribe at topica.com

For Topica's complete suite of email marketing solutions visit:
http://www.topica.com/?p=TEXFOOTER
--^----------------------------------------------------------------