Greg I am a great supporter of GFCIs
I think we should use them more often than required and I do just that, I install GFCIs at the point of use many times even when not required. Like you I feel an appliance that trips a GFCI has an issue that needs to be fixed.
That said I find it discouraging that you refuse to consider a real issue that
can cause problems no matter what may have worked fine at your own home.
Some reading that is more on target.
From EC&MTony Locker, BSEE, MSEE There is always a very small capacitive current flowing from an energized 120 Vac conductor to ground (by ground I mean the equipment bonding system consisting of the chassis, the bonding conductors, etc.). The capacitance to ground is distributed all along the conductor. That's why manufacturers of GFCI circuit breakers recommend the circuit length be limited to a maximum one-way distance of 250 ft., to avoid nuisance tripping. That's for 60 Hz circuits. As frequency goes up, capacitive impedance drops. At high frequencies (4-12 kHz typical of inverters), the capacitive impedance is low, so more capacitive current will couple to the bonding system and return to the source. This can nuisance trip a GFCI, which needs only 4-6 mA.
From a University of Idaho
pdf. • The issue:
– In any circuit, there is distributed capacitance
between the line or phase conductors, the
grounding conductor, and the surrounding
conductive materials
– This capacitance will result in a small
“leakage current”
– The leakage current may “pre-load” the GFCI
circuit breaker, reducing the normal trip level
From Square Ds GFCI breaker installation
pdf• Do not connect circuit breaker to
more than 250 ft. (76 m) of load
conductor for the total one-way
run.
I am in no way saying it will always happen, what I am saying is it can happen and in my own opinion a good design will place the GFCI as close to the point of use as possible to prevent this 'pre-loading' of the ground fault detecting circuitry.
A GFCI is worthless if it does start nuisance tripping and is removed by the customer.
I read your article. This is what it said about capacitance ... unless I missed something
If you consider that the wire is installed in metallic conduit (a code requirement) which is grounded, then you can understand that a capacitance exists between the conductors and the conduit. The longer the conduit and circuit length, the larger the capacitance.
The OP is talking about SO cord in plastic pipe.
In steel conduit is a worst case, the simple fact a copper EGC runs in parallel with the circuit conductors is also a problem although of lesser significance than if they where run in steel conduit.
