HI Kent, Thanks for that info. Makes sense
jay > On Jan 19, 2025, at 12:47 PM, Kent via RE-wrenches > <re-wrenches@lists.re-wrenches.org> wrote: > > Jay, > > If there is a PV ground fault, putting a short across the fuse holder may > cause damage by drawing an arc. Use a multimeter to measure voltage across > the fuse holder (should be the same as measuring voltage between PV negative > and ground); if there is no voltage then there probably isn't a PV ground > fault or any ground fault at that time. If there is voltage, then you need to > track it down. It isn't necessarily in the PV array - it could be a dc load > or even in the battery. If the voltage exceeds the battery voltage, the PV > array is the culprit. If you compute the proportion of the negative to ground > voltage to open circuit voltage then apply that proportion to the number of > modules, it should tell you about where to look. If you have multiple > strings, isolate the problem: disconnect all of the PV negative connections > and see which one gives you a solid voltage to ground. > > Kent Osterberg > Blue Mountain Solar > > > On 1/19/2025 6:57 AM, Jay via RE-wrenches wrote: >> Question about the fuses. >> >> For testing could you put a short test wire across the ends of the fuse >> holder and use a clamp on to test for current? Would it cause any damage? >> >> Instead of potentially going through lots of fuses? >> >> Jay >> >> >> >>> On Jan 19, 2025, at 7:48 AM, Mac Lewis via RE-wrenches >>> <re-wrenches@lists.re-wrenches.org> >>> <mailto:re-wrenches@lists.re-wrenches.org> wrote: >>> >>> >>> Hello Dana, >>> >>> Ground faults are tricky. Here is how I would tackle this on a sunny day: >>> 1. Visual inspection of array, looking for backsheet, wire damage, broken >>> glass, critter stuff (nests and bite marks). Look for water intrusion or >>> evidence that water has been somewhere that it shouldn't. >>> 2. Visual inspection of all splice boxes, checking for wire insulation >>> damage, evidence of water intrusion and critter entry. >>> 3. Probe voltage between +, - and Ground (do this at a string level >>> initially, and isolate strings and do this at open circuit). Any evidence >>> of bouncing voltage readings, loss of voltage, not rock solid voltage >>> suggests you may have a ground fault in that string. If its in the string >>> somewhere, you may see the voltage bounce and read in some fraction of the >>> string voltage. This can tell you where in the string it may be. FOr >>> example, if you have a 5 module string, you may get a 3/5 voltage reading >>> if the fault is near the 3rd module. >>> 4. Turn off array at combiner and run continuity tests between +, - and >>> Ground again (no gfp fuse). If you have continuity, this may suggest a >>> ground fault in conduit run between combiner and FM100. >>> >>> Good Luck, bring extra fuses! >>> >>> On Sun, Jan 19, 2025 at 7:07 AM Dana Orzel via RE-wrenches >>> <re-wrenches@lists.re-wrenches.org >>> <mailto:re-wrenches@lists.re-wrenches.org>> wrote: >>>> Yes I have 2 FM100s >>>> Dana Orzel >>>> C: 208.721.7003 >>>> E- d...@solarwork.com <mailto:d...@solarwork.com> >>>> >>>>> On Jan 18, 2025, at 7:08 PM, Kirpal Khalsa via RE-wrenches >>>>> <re-wrenches@lists.re-wrenches.org >>>>> <mailto:re-wrenches@lists.re-wrenches.org>> wrote: >>>>> >>>>> >>>>> Dana... >>>>> Do you have multiple FM 100s? If so only one should have the GFI fuse. >>>>> Broken panel with water getting into glass? >>>>> Turn it off and wait 5 min and turn it on. Usually clears it especially >>>>> if it's a faulty nuisance trip. >>>>> Have had numerous FM 100s give faulty afci errors. Removing the.afci >>>>> boards always resolved this issue. But of course check all you >>>>> connections leading to and from the cc. >>>>> Keep a few extra 1A gfi fuses handy....you may need a couple to test it >>>>> all out. >>>>> Keep us posted. >>>>> Good luck >>>>> Kirpal >>>>> >>>>> >>>>> On Sat, Jan 18, 2025, 2:40 PM Dana Orzel via RE-wrenches >>>>> <re-wrenches@lists.re-wrenches.org >>>>> <mailto:re-wrenches@lists.re-wrenches.org>> wrote: >>>>>> Hey, all you wise ones, >>>>>> 37 years in the business and I’ve never had a ground fault ever in any >>>>>> installation I’ve done or my home systems. I went out to my system here >>>>>> an hour ago and one FM 100 is completely turned off claiming ground >>>>>> fault on the mate 3S. >>>>>> I guess my first question is : >>>>>> >>>>>> Is this really a ground fault ? >>>>>> >>>>>> I had removed the ground fault breaker when I upgraded due to space >>>>>> considerations >>>>>> >>>>>> In my entire time in this business, I’ve never had to deal with the >>>>>> ground fault any suggestions on how I should be tracing this? >>>>>> >>>>>> Has anybody seen this in an FM 100 when it wasn’t a ground fault? >>>>>> >>>>>> I do own a megger& I’ve never had to use it. I only bought it about >>>>>> three months ago cause it seemed like a good idea and I might need to >>>>>> use one someday, Maybe I’m psychic ? >>>>>> now if I could just figure out how to trace this out. >>>>>> All suggestions welcome thanks all! >>>>>> >>>>>> Dana Orzel >>>>>> C: 208.721.7003 >>>>>> E- d...@solarwork.com <mailto:d...@solarwork.com> >>>>>> _______________________________________________ >>>> >>> > _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > There are two list archives for searching. When one doesn't work, try the > other: > https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > http://www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > http://www.members.re-wrenches.org >
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