Original poster: "tesla by way of Terry Fritz <twftesla-at-uswest-dot-net>" <tesla-at-paradise-dot-net.nz> Team Seem to recall a general guidline of at least 3 times the air gap distance to avoid surface tracking on G10 SRSG rotor. Intend to achieve 27mm of insulating distance to nearest ground (a little over 1") for a SRSG with PK Volts of 12.7kV. Any practical tips ??