All units passed the Oz standard 'test and tag' tests as would be expected. (insulation, continuity, leakage) Of particular interest, there was almost no earth leakage (<1mA).
The volt itself 'passed' the test and tag tester checks (as a non double insulated appliance). But still caused the occasional RCD trip. The delay and soft start of the volt charging meant that the test and tag tester had completed its checks before the volt charger had powered up. (note here... the test and tag system was unable to see the continuing volt earth leakage fault.)
A 4.7ohm 10W resistor was fitted in the earth line so an oscilloscope (floating) could monitor the earth current. (4.7V = 1A earth current)
A clamp probe could have been used, however we expected to need to see high frequency spikes so went with a simple resistor.
The volt charge was then started a few times. These spikes were not the J1772 contacts going in/out. There is a handshake delay before a contactor in the volt pulls in causing the spike.
We are looking at around 2A earth current here.
This more significant event caused an RCD trip...
Well it is 1.5A for 2mS. The RCD should trip.
An iMiEV was checked with the same setup and earth currents were significantly less. e.g.
OK, so the volt RCD tripping is real and caused by spikes at the start of charging.
The spikes are generally in pairs, one positive and one negative. The negative one (in this setup) seemed to be the offender that tripped the RCD. (but probably just the larger one anyway.)
The leakage is not continuous but is short (mS) and large in amplitude
(Amps) no wonder it trips RCDs.
So, what to do.
Ideas please guys.
A common mode ferrite core inductor for the active and neutral may help to balance the spike current in the mS range so the active to earth spike is seen on the neutral as well to partly satisfy the RCD.

edit: topic spelling !