Quote:
Originally Posted by SteveR
Update:
Tried two different cords...same problem
Tried different pigtail...same problem
Tried on 50A no problems
Tried on 20A No GFI...no problem
On any GFI I tried (different locations in storage area and at a friends house...the GFI pops.
All AC breakers except Mains OFf--pops on GFI
Took cord reel apart to look at connections--all look fine and tight.
Transfer switch connections are all tight and no wires out of place.
Still scratching my head here...
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Plug it back into any non-GFCI source, and measure current on the ground. Probably have to do that in the cord reel or some other place where it's readily accessible.
If a clamp-on meter doesn't read any current, probably because there's too little current to register, plug the shore cord into one of those adapters shown above and use a multimeter to read current through the little tab to ground (the box). Start with the 10A setting and (usually) the 10A port for the red lead. If still nothing, try the low current port.
Remember that you're putting your multimeter in series with the ground conductor, so take precautions, starting with measuring current starting with the highest capability device (clamp-on) and working your way down using the multimeter.
Since it doesn't trip the breaker on a non-GFCI source, it's not a dead-short type ground-fault (ground laying up against a hot). There's a leakage current through or from something, and measuring it may help in finding the source.
It's been stated several times at least, but I'll say it again - you need to unplug as many things as can be unplugged to find the leak. The neutral conductor
does carry current (obviously), and when it's carrying current it is no longer at zero volts to ground due to the impedance of the conductor(s), all the connections (including at each end of the cord). So when there's a voltage difference between the neutral and equipment ground, there will be current to the ground when they're connected, which is what's tripping the GFCIs.
Oh, and if trying the adapter, don't touch the little ground tab unless and until you know what the voltage and current is to ground. You might get a nasty surprise, especially standing on a concrete or dirt floor, or worse, if you're touching something well grounded (like the box itself) with the other hand.