Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>Just connect the center two connections together and float them, ie, don't ground them on the 240 VAC side. Apply hot 1 (H1) and hot 2 (H2) across the outer two LV bushings. Ground one side of the sec HV bushing (X1) and the output is off the other non-grounded bushing (X2). The pig's case is grounded and this point is also hooked directly to one of the bushings (X1).
This produces less stress on the HF sec coil as the interior side of the primary is at X1 (grounded) potential. Less chance of corona formation in this area as both the interior of the pri and bottom of the HF sec coil are both at ground potential.
Dr. Resonance
For the same reason that you don't tie the center LV bushing of a pole pig to ground when using it as a Tesla power transformer. David