[RE-wrenches] ground fault

[mac Lewis]

Hello wrenches,

One of our installers has been in the process of looking for an
intermittent ground fault for a couple weeks, and seems to be getting some
very odd behavior.  Maybe someone can help to figure out what is going on.

1 A GFI fuse seems to blow after 1-2 weeks, certainly not instantaneous
Doesn't appear to be related to moisture, has happened in very dry
conditions
After jiggling the wires around a bit yesterday, and unlanding the DC
strings to the inverter, he was able to see a ground to DC negative voltage
of 60V.  Aha!  He thought, the ground fault must be 2 modules into the
string from the negative homerun.  They examined all of the wiring,
everything looked fine, replugged it back in, and were surprised to see
120V from ground to negative at the inverter.  After more jiggling, the
voltage disappeared completely of course.

No apparent wire damage.  The change in voltage from ground to DC negative
is what has me very confused.

I will be heading out there today to take a look.  I could use some ideas.


Thanks

-- 



Mac Lewis

*

"Yo solo sé que no sé nada." -Sócrates
*
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