The increase in AC resistance over the simple skin effect is studied in short coil windings and twisted wires. The effect of conductor spacing is examined showing increases in AC resistance in excess of 100%. The effectiveness of stranded and/or twisted wire to both self and proximity fields is developed. These models are used to predict the experimentally measured AC resistance of coils.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>