The simplest method I can think of right off the top of my head would be to use a Wiggy and an extention cord.
Plug the extention cord into an outlet which is either ahead of the GFCI, or on the opposite Ungrounded Line Conductor [other "Phase"], then test with the Wiggy between one terminal of the GFCI ["Hot" or "Noodle"] and whatever terminal on the cord that gets a complete circuit going.
That's about the most simple and least hazardous method I can think of right now [you have my interest on this big time!].
Alternate method, of course, is to find some Grounded Metal item and clip a long test cable to it, just to drive an unbalanced current through the GFCI device.
Using the idea behind random nuiscance trips when starting some Cap Start Induction Motors [I have heard of this and read of this, but never experienced it!], maybe there's a way to draw an imbalance of current through the GFCI device [possibly via one or more recepts on the load side] using various Reactive components - such as Capacitors and Inductors, possibly with a Variable Cap [like a tuning Cap], or a Variable Inductor [a "Variac" might work] - or both!
Maybe even some form of Tank Circuit between the GFCI device and "Downstream" receptacles would be able to either push an imbalanced current on one circuit conductor, or draw an imbalance on one conductor.
Trying to get a current above 6ma to flow - and not setup a hazardous situation - is the biggest problem to deal with [IMHO].
I could draw an imbalance of microamperes easilly, possibly reaching upto the 1.0ma range, just by connecting certain components to a circuit, then driving the current into the earth [dirt] either by a direct dirt connection, or on a nice damp concrete slab. That's just not gonna cut the mustard, though! [where did that term come from???]
Going to do some thinking and maybe even some smoke testing on this over the weekend.
Scott S.E.T.
