Thanks, but I need it very accurate so need the equation for square. - Paul At 11:58 AM 7/1/2008, Gene Smar wrote: >Paul et al: > > Here's one equation for round conductors: > http://emc.ice.uec.ac.jp/~xiao/Wire/index.html , and scroll down > the page a bit. Would that be adequate? > >73 de >Gene Smar AD3F