990. In order to definitively determine whether or not fuse «3», shown in the illustration is blown using an on-line testing technique, across what points would you connect the voltmeter leads

An on-line fuse test requires comparing the load side of the suspect fuse (bottom of fuse 3) to the energized line side of a good phase (top of fuse 1 or 2) to identify a blown fuse, which will result in a reduced voltage reading.