Laminated Copper Busbars

NEC article 366.23(A) supports maximum 1.55A/mm² (or 1000A/in²) for bare copper bar.

You also can see http://www.husseycopper.com/Bar/busbarselector.htm

Good luck.

- MS

CR4 Admin: removed broken link

All the formulas you find, are based on the temperature the bus bars will reach under steady state conditions in free air. If those are the end use conditions for your bus bars, then use the tables. If your bus bars oprate in conditions that remove more heat (e.g. forced convection, fluid immersion, etc.) then the formula is not accurate for your conditions. Under those conditions you can operate at higher current.

It's really a matter of physics of current flow and thermal management. One of the great things about copper is it's thermal conductivity. One of the not so great things is that reacts with lots of things given its atomic structure, such as oxides and ionics.

Both of which result in degradtion, therefore you might want to consider immersion and or plating. I would look into immersion since you would get the biggest bang for the buck. Of course that approach must be consistentwith your physical/logistical constraints.