[RE-wrenches] Insulation Resistance Testing with Klein ET600

[Jason Szumlanski]

If anyone is using this tester to do insulation resistance testing, I would
appreciate any pointers you have.

I have used it successfully to test home run DC strings from
rooftop junction boxes to inverters to check for nicks in wires and hard
faults to ground or short circuits. However, I am currently facing a
Sol-Ark 15K with three strings of PV that all seem to cause an intermittent
DC insulation fault (F24). I have isolated each string by disconnecting the
other strings at the rooftop junction box. With only one string connected
to the inverter, regardless of which string it is, I will eventually get
the F24 error.

Since I have ruled out the home run wiring, It appears the issue must be
within the array somewhere. I would like to use the ET600 to help track it
down, but I am reading conflicting information on how to properly undertake
the test on each string. I know that I can disconnect the conductors
between each PV string and the junction box and test each jumper wire
individually while disconnected. But what about the PV module leads
within the string of connected modules? I'm suspecting a pinched PV module
lead somewhere, but I don't know where to start looking.

Jason Szumlanski
Florida Solar Design Group
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