Original poster: "Rodney Goolsby by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jeronimo-at-bright-dot-net> I know that John Freau's equation says that the spark length for a 12/30 NST is 3 feet (or very close), but in actuality what is the average sparks people get from any TC powered by a 12/30 NST?