Thank you for your question regarding routing neutral wires separate from the hot wires, it is our pleasure to help.
Your question is a bit out of our expertise, but we can tell you that it is not only a very bad idea to route a neutral separately from the hot wires, but is illegal under that National Electrical Code (NEC). Please see NEC Articles 215.4(B), 300.3(B), and 300.20(A).
The reason for this is due to induction, not hysteresis. The neutral wire helps to cross cancel the magnetic fields that form in the hot wires as the current flows through the conductors. Without the neutral, you will cause inductive heating of the metal conduit. One of our engineers has actually been to a facility that routed the neutral separately from the hot wires in a high-current circuit and had heated the metal conduit support columns to the point that they actually glowed red-hot!
The bottom line is that the neutral wire must be grouped with the hot wires. Not only will this reduce inductive heating of adjacent metal objects, but it reduces the generation of electrical noise, reduces accidental power outages, and many more negative things. And of course, it is a violation of the National Electrical Code.
We hope you find this information useful. If you should have any further questions, please do not hesitate to contact us again in the future.
The Engineering Team at E&S Grounding Solutions
Photo credit: http://www.flickr.com/photos/makerbot/4905207514/sizes/o/in/photostream/