Electrical Q
#22
(11-16-2020, 02:49 PM)Roly Wrote: Going back to my original response of too much capacitance in the circuit due to excessive circuit length, normally over 150'.   If you dont have the ground bus grounded anywhere  it should not trip because of a parallel path.   Try plugging the extension cord in a non gfci  outlet and place a gfci in or near the moved house and see if it trips.   Roly

Roly is pretty smart so I figured I'd try to estimate the capacitance of the 150' cable by guessing gauge and using some online calculators.

I got an approximate value of around .002uf or thereabouts.  Then I got to wonder what kind of sensitivity GFCI protectors feature and did some googling and came upon this:

Quote:https://safeelectricity.org/ground-fault...ers-gfcis/

What is nuisance tripping of a GFCI?

It takes only 5 mA (0.005 A) of current leakage from the hot wire to the ground to cause a GFCI to trip. A small amount of leakage current may be difficult to avoid in some normal circuits. Hand-held power tools do not cause a tripping problem if the tool is maintained in good condition. Some stationary motors, such as a bathroom vent fan or fluorescent lighting fixtures, may produce enough leakage to cause nuisance tripping. Another problem may be a long circuit with many splices. If possible, keep GFCI circuits less than 100 feet long. To avoid nuisance tripping, a GFCI should not supply:
  • Circuits longer than 100 feet
  • Fluorescent or other types of electric-discharge lighting fixtures
  • Permanently installed electric motors

So I think Roly is onto something here (note the parts I set in italicized bold).
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