Capacitance from motor windings to the motor shell of more than 0.09 uF will also trip these things, in addition to internal RF filters to protect electronic circuitry.
With all the discussion about GFCIs and AFCIs, I hope these things actually save some lives, compared to not having them. I couldn't find any before and after data on this.
With driving in a car being 30x more dangerous than electricity on a per year basis, does the NEC/UL and various elec. manuf. have this?
And watch out for
as far as how reliable or not these things are.