Original poster: "Tim J by way of Terry Fritz <twftesla-at-qwest-dot-net>" <digital_raven45-at-hotmail-dot-com> Most..if not ALL MOT's use a special rapping tape called NOMEX mica. It is used to insulate the primary and secondary portions of the MOT. Varathane is also used to further insulate the secondary. NOMEX mica tape is good to 10,000 Volts AC RMS.