Misleading fault indications [RE-wrenches]

[Mark Frye]

William,

The fault condition is a ground fault. Why is it that the tripped GFI
breaker must only indicate a PV ground fault?  The ground - negative bond is
the bond that serves the PV and the battery/inverter circuits, so why should
the tripped breaker not indicate a ground fault in either circuit?
 
Mark Frye
Berkeley Solar Electric Systems
271 Vistamont Dr
Grass Valley CA 95945
(530) 401-8024
www.berkeleysolar.com
 
-----Original Message-----
From: William Miller [mailto:wrmiller at charter.net] 
Sent: Thursday, February 28, 2008 11:21 PM
To: RE-wrenches at topica.com
Subject: Misleading fault indications [RE-wrenches]


Colleagues:

We have been installing a number of off-grid systems which include the 
Outback GFI breaker assemblies.  This is multi-pole breaker has one 0.5 amp 
pole which is connected between the ground and neutral busses.  This 0.5 
amp pole replaces the wire that usually bonds the ground and negative 
busses together.

I wonder if removing this bonding wire causes another problem.  That 
problem is illustrated in the following link  Click on the second case, 
"Misleading ground fault indication:"

http://mpandc.com/case_studies/ground_fauilt/ground_fault.html

I am interested if anyone else sees this problem or has wondered about 
this.  I am hoping I am just seeing it wrong.  If I'm right, there are some 
serious implications.  I appreciate your opinions on this.

William Miller



-- _________________________________
William Miller
Miller Power and Communications
Voice :805-438-5600     Fax: 805-438-4607
email: wrmiller at mpandc.com
http://mpandc.com
License No. C-10-773985


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