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Dan:
The reason for using a 100 ohm, or some other value to measure leakage current is that this saves the cost of replacing the meter fuse, like $15 for Fluke, if you have a high high and unexpected current. Small resistors are cheap at a few cents each. The choice of resistance value is a function of expected leakage current.
If your measured output voltage was 10 V or so, then was this with no load on the current sensor output? A high impedance meter input is typically in the 10 Megohm range. One microampere thru 10 megs is 10 V.
With no current thru your sensor load the output with 10,000 ohms. What is the voltage across the 10,000 ohm resistor? One microamp should be 0.01 V.
Also use your DVM to measure the contactor coil resistance. Can you see a shading coil (copper slug on part of the contactor pole piece)? Search Google for --- shading coil contactor photos.
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