>Lexan (polycarbonate) has a strength of 364 volts DC per mil, so a piece >of 1/4" would stand up to 91,000 VDC, theoretically. Depending mostly on >what you're going to use the bobbin for, this should be greatly >underated. > > I guess it should hold up to 12-15Kvac. I building a transformer and the secondary will be on a bobbin directly over the primary. It may take me six months to wind the secondary though! Frankensteins Helper Max