Gfci question

mrkelleysaid

looking for some advice.. I have two ac circuits distrib panel that are gfci, they trip for no apparent reason randomly sometimes a day sometimes 16 hrs etc. completely off grid mspae 4448, through mmp panel... Bond is in the panel as was easier to leave that way, inverter neutral bond removed. On generator also fine. No loads coming on off i.e.: fridge, sq grunfos pump etc make the trip. It seems to be completely random and as said won't happen for hrs or a day. Checked receptacles fine and they have been running on the gen set for three months sold till the inverter went in two weeks ago never tripped. All output ac voltages fine, scratching my head obviously there is a small fault just can't seem to figure where it could be...as it happens on one circuit and later to the other.. don't want to just change to no gfci if I am missing a safety/heat generating problem.
any ideas greatly appreciated

mcgivor

Intermittent faults are the hardest to trace, there are 2 ways, the best is to use an insulation resistance tester or Megger "trade name" which uses a high voltage to breach insulation break down, which multimeters cannot detect. Typically they use 500 or 1000 volts to pulse between the live conductor and ground of branch circuits first, then feed circuits, caution must be taken to ensure no sensitive electronic appliances are connected, including any surge protection devices. Unfortunately most people don't have access to an insulation resistance tester, but if one can be obtained I would highly recommend using it.

Second method is divide and conquer, eliminate one circuit at a time, then devices one at a time, check for moisture in junction boxes, if split phase ensure the GFCI's are not on the same line to see if the fault is isolated to one leg. This is an extremely time consuming exercise, akin to fault finding in braille, having the correct tools is invaluable. Are the GFCI devices breaker type or receptacle type? The latter are notorious for random tripping.

mike95490

When my house was built, I had a 30% failure  rate with hard wired (code required) smoke/Co detectors, and 20% failure on the outlet box GFIC's. Spent 8 months swapping them out as they failed.

BB.

Do you have dimming (or brightening) lights when (for example) a refrigerator or well pump starts up (new problem)?

I had problems with lights dimming and brightening (did not seem related to loads). And then a few months later, I had problems with GFI outlets popping (mostly my washer/drier outlet). Replaced the GFI outlet, and the problem continued (actually replaced the outlet because it self destructed after ~15 years since new--The plastic got brittle and the trip/reset buttons just shattered).

Turned out the problem was a drop from my utility line (120/240 VAC utility drop) that had gotten wet (just a few teaspoons of water over ~15 years that came in through the weather head) and it corroded the meter socket wire binding).

It was weird. Definitely showing signs of some overheating on the wire binding from getting a little wet, but other than "flashing" lights and random GFI failure, no other indications that I could find (voltage/current/etc. readings were all fine). I just had to check every wire connection (outlets, wire nuts, breakers, etc.) until I finally popped the utility meter from the socket to find the corrosion. Replace the meter socket and one cable (too short to just trim the bad end off)--And all of the problems "went away".

-Bill

Estragon

Were ALL connections retorqued ~1 day after the inverter was installed? It's surprising how much looser they can be the day after initially tightening them down.

Also, if stranded wire was used anywhere, check especially closely when retorquing. With the finely stranded in particular it's easy to miss a stray strand going somewhere it shouldn't.

mrkelleysaid

I will try retorque idea its so strange ...no drop or dimming lights actually fridge and well pump doing much better on inverter as expected. I was reading an outlet when the well pump kicked in and refridgecompressor was on 1 volt drop like 120 to 119 so not that mag inverter working perfectly. I am wondering about the dish network and hughesnet ground tie in at the rod as the snow was falling it popped will try to document atmospherics too now they got some power in those rg 59 calves saw a arc when relocating the splitter hmmmmmm.  Thanks all any other thoughts 

BB.

I like gfc outlets vs gfc breaker in the main panel. Much easier to find bad devices and you do not drop an entire branch circuit if there is a true ground fault.

But gfc outlets are not always reliable.

-Bill

2manytoyz

I have a love/hate for GFCIs.  In some applications, they're fantastic.  But the ones on two different Xantrex inverters trip periodically.  I had a fridge connected to one, and a HF attic hoist to another.  I've since removed them from the inverters on these two appliances, and have had zero issues.  I can put a GFCI outlet downstream for outside or near water use.  At least that way, I don't lose all power if it trips.

My solar setup also doubles as emergency power during major power outages, like the hurricane last year.  When we came home a couple of days later, the inverter had tripped (again).  The garage door opener would operate, and the fridge was warm.  The GFCI caused more issues than it solved, in my application, so out it went.  YMMV.

Dave Angelini

Is that in Florida electric code to use a GFCI on a refrigerator circuit? I don't think so... Seems pretty crazy to me!

2manytoyz

Dave Angelini said:

Is that in Florida electric code to use a GFCI on a refrigerator circuit? I don't think so... Seems pretty crazy to me!

I'm using a home built transfer switch to critical loads in my house.  When the grid goes down, my fridge, CCTV system, lighting, etc., all move over to to inverter power.  Nothing I've connected require a GFCI, but the inverter had one built-in.  My Xantrex inverter is really intended for RV or marine applications, which is why the GFCI is built-in.  But for the price, and the quality of the output, it's a good option in my application.  I've created a solar powered UPS.