Non-uniform coil current distribution resulting from various electromagnetic phenomena has a dramatic effect on induction coil life and crack development in the coil copper. This article is one of series of articles devoted to a systematic scientific/engineering analysis of failures of induction heating coils and prevention. Article concentrates on coil copper electromagnetic edge effect, effect of frequency and coil copper tubing geometry on current density distribution. Other factors that affect electromagnetic edge effect (i.e., flux concentrators, magnetic flux intensifiers, flux controllers, frequency selection, etc.) are discussed here as well.