After much searching, found this posted by @STEVETERRY to another forum:
PULLING THE NEUTRAL
This is easiest to understand by making a drawing. Draw a thee-phase service feeding three 575W, 120V lamps, each connected between a phase and neutral. So far so good.
Now erase the neutral, but leave the three lamps connected together at the neutral point. This is what happens when the neutral is pulled. Now, as long as the loads on the three phases are identical, they will continue to work, and approximately 120V will be delivered to each. That's because, in this case, the "fake neutral" point, while not tied to the transformer neutral, is a voltage divider created by the loads that is electrically equidistant from the three phases.
However, the "fake neutral" created in this scenario is dependent on the size and setting of each of the loads. If individual loads change, the "fake neutral" moves around electrically with respect to the three phases, resulting in overvoltage on some phases and undervoltage on others. This can blow up lamps and control equipment. In addition, no phase-control dimmer can operate properly without a solid, low impedance neutral connection to the transformer.
This is why it is not code-complaint to have any overcurrent device in the neutral, unless it is a four-pole, common-trip device that disconnects the three phases and the neutral simultaneously.
ST
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