Ground fault [RE-wrenches]

[sunwise]

Greetings William,

There must have been a lot of current going though that CC.  I didn't
know the RV products would allow reverse current flow.  Wasn't there a
fuse or DC rated breaker between the CC and the battery?  I usually
place one both between the battery and the CC and between the CC and the
array.  It seems to me such over current protection would have prevented
this almost as well as a GFI.

Kurt Nelson
SOLutions

-----Original Message-----
From: William Miller [mailto:wrmiller at slonet.org] 
Sent: Thursday, November 14, 2002 4:31 AM
To: RE-wrenches at topica.com
Subject: Ground fault [RE-wrenches]

Colleagues:

Over the last weekend I received a call from a client reporting that an
RV
products SB50 that I installed for him had "burned up."   I went out
first
thing Monday to look at it and almost pooped my pants. The unit had
burnt
inside to a crisp and damn near sent his warehouse up in flames.  This
was
some serious fire and it scared me.

We have performed some analysis on what caused the problem and posted a
pretty comprehensive report on our web site (url in my signature lines
below.  Click on Case Studies.  The photos and diagrams are somewhat
large
to show adequate detail, so download this when you have the time).

Part of the problem may be that the client keeps adding legacy Cariso PV
modules.  He wants to increase his charging and may well have exceeded
the
capability of the SB50.  One reason he adds modules is that he may not
be
getting a realistic charge rate because the ground fault we discovered
may
have been siphoning off amps for some time.  The problem may existed for
some time and came to a head when we finally received rain here after a
long dry summer.  The ground conductivity may have increased enough to
bring this problem to a critical point.

The only reason the fire did not spread is that the client put a sheet
metal cover over the equipment to prevent water damage in the case of a
roof leak.

I believe there are two lessons to be learned:  Ground fault breakers
may
be more valuable than I could have imagined, and sheet metal backing is
a
valuable addition to any installation.  These are both ideas discussed
here, and they may warrant further discussion.

I was off the hook on this installation because the client wired his own
arrays.  Having said this, it would be very easy for anyone to create
this
kind of fault.  Using tray cable, for example, one could easily pinch a
positive wire in a rack foot when lowering a rack.  All of this scares
me
and makes me want to perform all of my installs like delicate surgery.

Comments are appreciated. I especially want to hear if anyone agrees or
disagrees with the premise that a GFI would have prevented the failure.
If
so, the point is not to require a GFI when the arrays are on the roof of
a
dwelling, but when any of the circuitry is IN or runs through the
dwelling.

Thanks for reviewing this case and commenting.

William Miller

__________________________________________________________________
William Miller
Miller Power and Communications
PO Box 50, Santa Margarita, CA 93453
Voice :805-438-5600		Fax: 805-438-4607	VMail:
805-546-4875
email: wrmiller at slonet.org
http://millerpowerandcomm.com
License No. C-10-773985
_____________________________________________________________
Compatibility:
Word processor: WP7
Spreadsheet: Quatro Pro 7
CAD: Microstation 95, DXF, Visio 4.1T
_____________________________________________________________
"Every decent man is ashamed of the government he lives under."
                                    H. L. Mencken
__________________________________________________________________

- - - -
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

- - - -
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.bWljaGFl
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
==^================================================================