Original poster: "D.C. Cox by way of Terry Fritz <twftesla-at-qwest-dot-net>" <resonance-at-jvlnet-dot-com> The 8.7 kV (not 87 kV) value is actually for the sec. coil. I failed to notice he was talking about the primary which is 60 Hz when it tries to break down the initial gap. D.C. Cox