The forum thread cam up on 05/13/2008 . You could have seen it if you have searched properly.
See my reply to it below and read aall other replies :-
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The size of the bus bar for electrical panel is based on the rated current and short circuit current. The configuration , orientation,Clarence of bus bar , single or multi busbars and ambient temperature are other factors. The current carrying capacity of the bus bar will depend on heat dissipating capacity of the bus bar chamber and depends on horizontal or vertical orientation. The size of the bus bar are also decided by the skin effect and Proximity effect( when multi bus bars are used) of the conductor and the metal used (that is copper bus bar or the aluminium bus bar).The bus bar manufacturers normally provide the capacity rating for various standard sizes . It is for the designer to select the correct size and configuration.
The design of bus bar is highly technical job and needs through knowledge. Better consult a competent consultant as it is not the job of armature."
I googled "bus bar ampacity" and the first hit answered your question. A little effort on your part will reap great returns from the vast knowledge on this forum. I am a believer that your should sign in as a member instead of a guest. It makes the post more personal.
That would be a waste of time and material. If your load is as large as you seem to indicate all you need to do is determine the amp load and go to the site I listed and pick the size of the bus bar. Its that simple.