Skin effect works at all frequencies besides DC. At 60 Hz it’s 8.5mm. So, solid conductors thicker than 17mm have some skin loss. You can mitigate this by windi

Skin effect works at all frequencies besides DC. At 60 Hz it’s 8.5mm. So, solid conductors thicker than 17mm have some skin loss. You can mitigate this by winding multi strand wire in a particular way, though.