Both yesterday and today HAM2 ISI tripped, with no obvious reason.  Both times I looked at the camera, and did not see any work around the chamber.  Yesterday the HAM3 ISI tripped at the same time.  Both happened while doors were being taken off / put on in the HAM4/5/6 area.   Snapshot shows today's HAM2 ISI trip, and yesterday's HAM3 ISI trip.