On Fri, 16 May 2008 22:34:38 GMT ehsjr wrote: | snipped-for-privacy@ipal.net wrote: |> On Thu, 15 May 2008 04:07:52 -0400 John Gilmer wrote: |> | |> | |> |> My trips in a hydroponic application have usually been when pumps turn |> |> off. |> | |> | That "computes" since the opening of the circuit would cause a "voltage" |> | kick from the induction of the windings. That higher than normal voltage |> | is more likely to find a leakage path to ground than normal line voltage. |> |> But would that kick be transferring part of its current flow back to the |> GFCI? If the hot wire opens (by the relay cutting off the compressor), |> then the kickback current would be on the neutral, but not the hot. Is |> that at least part of the explanation? |> | | The GFCI does not know the difference between hot and | neutral. It trips based on the imbalance of current | on those two wires. A pulse on either the hot or the | neutral that is not accompanied by an equal pulse on the | other wire creates an imbalance that will be detected by | the current transformer. If the imbalance caused by the | pulse is long enough and of sufficient magnitude, the | GFCI will trip.
You're describing the correct theory that suggests this can happen. But the big question is if that kickback, which would be on the neutral and thus be a difference current, be sufficient to trip the GFCI. I suspect it can be.