Hi Mark, What you are talking about is all part of what goes into the final effective resistance. The 1 to 2 milliohm figure is an educated guess but it is roughly what I think you will see even after the heating effect that you are talking about. What goes on at the interface between two pieces of metal in an electrical contact is very complex and to some degree, at the microscopic level, heat can actually help make the connection better by microscopic melting. I'm sure that the total contact area is actually much less than the cross-section of a 10 AWG wire but because the path length is so short, the total contribution to resistance (or voltage drop) is only moderate. Sean On Thu, May 17, 2012 at 7:31 AM, Mark Hanchey wrot= e: > On 5/16/2012 8:55 PM, Sean Breheny wrote: >> I agree, Bob. The resistance of good clamps on fairly clean metal is >> going to be maybe 1 or 2 milliohms per connection. This would be 8 >> milliohms max for the entire circuit. > > The resistance is not the problem, it is the small surface area making > the connection on both ends. The clamps on most cables have very small > contact area with the terminals. It would not surprise me if the contact > area was equal to that of a 10AWG wire. The resistance may read as 0 but > that will change when the metal begins to heat up from a lack of being > able to handle the high currents. It is like trying to power a home > using a needle at the end of the service wire and expecting all 200 amps > to flow across the needles contact point. > > Mark > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .