Steve, I believe the half wave rectifiers will give you a current draw only during the positive or negative half of the alternating current. The full wave rectifiers will give a current draw during both halfs of the alternating current.
True, but this doesn't help the neutral any. Assume for the moment that switching power supplies in computers in a server farm draw large spikes of current that last 10% of the 60 Hz cycle time. These supplies use a bridge rectifier or voltage doubler circuit, both would draw current spikes at the positive peak and the negative peak of the phase that they are connected to. Think in terms of time: computers loading phase A will draw a spike of current at the top (positive) of phase A, and return it to the neutral. Call the start of this spike time zero. a full cycle of 60Hz lasts 16.7 msec. The spike lasts for 5% of that time, 0.83msec. Computers on phase C will see the negative peak of that phase 2.77msec later, and their current spike will last 0.83msec. ANd so on thru the rest of the positive and negative peaks, total of 6 over one 60Hz cycle. None of the spikes returned on the neutral overlap in terms of time. Thus the neutral sees 6 current spikes, and any one hot phase wire only sees 2 spikes in one 60Hz cycle time. Thus: neutral current = phase A current + phase B current + phase C current in the worst case. If this were a system feeding pure resistors, each load would be drawing overlapping currents, and the neutral would see no current at the panel (assume all 3 phases equally loaded here).
