Okay, just to make sure I understand and that I am providing the right information I dug up a diagram of how an OR theatre should be wired according to CSA's Z32 code book regarding health care facilities. I have done some work in an OR theatre as far as taking the cover off the panel and inspecting the guts so some of this looks familiar:

[Linked Image from i58.tinypic.com]

If I understand you correctly, a DMM would measure a percentage of supply voltage from L1 to grnd and N to grnd because of the ground detection device (Line Isolation Monitor?) but if it were out of the circuit then there would be zero voltage measured?

BTW, the measurements I took on my isolation transformer were done with a Fluke 117 with 5 Mohm R and the Weston has 11.535 Kohm R at 150 V setting.

A malfunction at the junction
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Dwayne