Hi All, Found an article on Litz-wire. On first scan it appears to give calculations and graphs on stranding number vs gauge vs AC resistance vs DC resistance. It contains a 27 references to previous works on skin-effect and eddy-current papers. Optimal Choice for Number of Strands in a Litz-Wire Transformer Winding by Charles R. Sullivan IEEE Transactions on Power Electronics, Vol. 14, No. 2, March 1999, Pages 283 to 291